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Title: misfiring badly at 50 mph Post by pedropedro on Sep 15th, 2011, 1:03pm 2.3 recently sorted wiring issue edis/ecu.........now has a problem at 50mph +/- 5mph I can feel the engine sort of jerking.. missing a beat if that makes sense ..almost feel a jump. like drive train backlash drives perfectly at all other speeds; doesnt miss a beat at 70 plus...idles perfectly...could it be coil packs/injectors ?? but if it were would it run smoothly at 70 and idle ok ..dont know where to start ....any input appreciated |
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Title: Re: misfiring at 50 mph Post by Scorpio_Mike on Sep 15th, 2011, 1:07pm Sounds like coil packs or wiring ??? Have you cleaned the MAF ? |
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Title: Re: misfiring at 50 mph Post by pedropedro on Sep 15th, 2011, 1:29pm yes cleaned maf...tks for comments |
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Title: Re: misfiring at 50 mph Post by Mike H on Sep 15th, 2011, 1:47pm Mine used to do that as well, cleaned MAF, no difference; new MAF, sorted, as if by magic. ;D The "acid test" to double-check if MAF is the problem, try driving it with the MAF unplugged. (PS: it also needed new cat, exhaust and filters as were all very bad, but still pretty sure jerking was mainly the MAF) |
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Title: Re: misfiring at 50 mph Post by pedropedro on Sep 15th, 2011, 3:44pm ok will give it a go tks |
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Title: Re: misfiring at 50 mph Post by pedropedro on Sep 15th, 2011, 8:29pm well I am pleasantly surprised...disconnected the maf and it runs perfectly...also a gearbox flare I had 2-3 seems to have gone.....happy days ! thanks for advice |
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Title: Re: misfiring at 50 mph Post by Mike H on Sep 16th, 2011, 9:10pm Terrific, so now we know what's doing it ;D Amazing what effects it causes, mine couldn't hold 4th properly, as though the lock-up clutch was burnt out, finally resulting in flashing O/D light |
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Title: Re: misfiring at 50 mph Post by Mike H on Sep 16th, 2011, 9:19pm PS: so what's the plan now, try another MAF? |
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Title: Re: misfiring at 50 mph Post by pedropedro on Sep 16th, 2011, 10:05pm ordered a new one...but runs fine without ! |
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Title: Re: misfiring at 50 mph Post by Mike H on Sep 18th, 2011, 1:13pm Fuel consumption might be worse though, as it can't measure the precise amount of air coming in so has to resort to a more basic fuelling map. Just guessing... |
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Title: Re: misfiring at 50 mph Post by pedropedro on Sep 23rd, 2011, 12:09pm put new maf in and it does exactly as before with original maf ie erratic at 50mph...maybe maf makes fuel leaner and shows an underlying fault elsewhere...could blocked injectors do this?? really bad exactly at 50mph all other speeds fine so earlier idea coil packs ..if they were bad would that produce those symptoms...also with no maf engine died a couple of times when idling..maybe to be expected ??? any help greatly appreciated |
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Title: Re: misfiring badly at 50 mph Post by Mike H on Sep 23rd, 2011, 1:21pm When you say "new MAF", brand new or 2nd hand? If it seems to be perfect without, can't be much else seriously wrong. |
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Title: Re: misfiring badly at 50 mph Post by pedropedro on Sep 23rd, 2011, 1:38pm brand spanking new £103 worth ..there is something underlying 100% which i need figure ...it died on me twice without maf maybe a clue...i think no maf its running richer and masks the problem ... |
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Title: Re: misfiring badly at 50 mph Post by Mike H on Sep 23rd, 2011, 5:33pm Possible, inlet manifold air leak or idling control valve sticky? |
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Title: Re: misfiring badly at 50 mph Post by singlefin_scott on Sep 23rd, 2011, 8:23pm Hi, Just a thought i may be completely wrong, but i have heard that a faulty/ broken fuel shut off loom can cause these kind of probs ! Could this be correct ??? |
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Title: Re: misfiring badly at 50 mph Post by pedropedro on Sep 24th, 2011, 9:05am think if manifold leaking it would run leaner and problem would get worse would idle control valve affect 50 mph speed ? ...its not loom recently replaced but thanks for input any help would be appreciated as its quite bad...guess can disconnect the maf again but need a resolution |
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Title: Re: misfiring badly at 50 mph Post by Mike H on Sep 24th, 2011, 2:00pm Have to confess I'm a bit lost now When was last time plugs were looked at? Also, albeit if wiring is good, how about cracked coil packs (?) |
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Title: Re: misfiring badly at 50 mph Post by Cosray on Sep 24th, 2011, 4:11pm Hi Pedro, I had a Scorpio doing this and it turned out to be bad wiring related to the EGR Differential Sensor. So at certain speeds it would confuse the EEC/V by erratically opening-closing the EGR/Valve injecting exhaustgasses when it should not. If you follow the 3/wire loom from the EGR Diff Sensor downward it sprouts from the main engine compartment loom where. Do inspect it for brittle, bad isolation. While I write this it could also be the vacuum management of the EGR System as a whole, rattling or leaking causing instability at certain speeds. There´s a good writeup on the website here http://www.fordscorpio.co.uk/egr.htm Do you have OBD/II capability? That could give a clue perhaps HTH Ray |
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Title: Re: misfiring badly at 50 mph Post by pedropedro on Sep 24th, 2011, 4:34pm Hi Ray...that sounds plausible.......will check out that wiring,.,,yes have obd2 peppers no codes though ,,,,guess i could do a journey record a session and see what comes up ..tks for tip john |
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Title: Re: misfiring badly at 50 mph Post by Mike H on Sep 24th, 2011, 5:02pm Good article that, note e.g. paragraph: "My vehicle suffered from a persistent misfire under very light throttle conditions ...." Actually, my EGR has seized up a couple of times along with all the other things that weren't right up until it all got fixed last year, it would need an overnight soak in summat to get it working before it would pass an MOT test |
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Title: misfiring badly at 50 mph Post by pedropedro on Sep 24th, 2011, 5:05pm just checked wiring ok...checked egr by putting tube on and sucking can hear massive change then reverts to normal so assume valve ok....checked after and there is an egr code but that maybe was my disconnecting....will do a run and recheck... |
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Title: Re: misfiring badly at 50 mph Post by Cosray on Sep 24th, 2011, 5:17pm Here´s a pic of connection of the ventury into the exhaust and inlet housing. Might be worth checking if all that sits bolted tight and not rattling-leaking. http://www.fordscorpio.co.uk/images/p9030017.jpg taken from HERE± http://www.fordscorpio.co.uk/24vrebuildegr.htm HTH Ray |
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Title: Re: misfiring badly at 50 mph Post by pedropedro on Sep 24th, 2011, 5:38pm ok tks for that Ray...will run now for a day and check for that code again think p1041 ..but suspect i induced when i had tubing off |
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Title: Re: misfiring badly at 50 mph Post by Mike H on Sep 25th, 2011, 12:45pm I presume closed-loop fuelling (MAF unplugged, engine cold etc.) also means EGR is not used. |
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Title: Re: misfiring badly at 50 mph Post by pedropedro on Sep 25th, 2011, 12:48pm thats a good point .... |
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Title: Re: misfiring badly at 50 mph Post by Mike H on Sep 25th, 2011, 1:02pm If code is P1401, this page ... http://www.fordscorpio.co.uk/egrmonitor.htm ... suggests DPFE (little black box) sensor electrical test fail or gas flow test fail, possibly 'cause you took a hose off. Don't forget also you might have a split / leaky hose somewhere. HTH |
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Title: Re: misfiring badly at 50 mph Post by Mike H on Sep 25th, 2011, 1:06pm on 09/25/11 at 12:48:01, pedropedro wrote:
I thought so too ... ;D That page also says at the bottom "However, if the system is not gas-tight then air can be drawn into the inlet system instead of inert gas. This can weakens the mixture sufficiently to cause misfiring, and manifests itself as a noticeable misfire/hesitation at speed and light throttle, not present when accelerating. If the leak is serious enough it may manifest itself as a hunting/rolling idle, caused by an unmetered leak of air into the inlet" |
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Title: Re: misfiring badly at 50 mph Post by pedropedro on Sep 28th, 2011, 2:03pm checked all gas connections re egr and is fine...also stalls occasionally and gives a lurch when idling after 60 secs......problem most evident when taking foot off at 40-50mph can feel the engine lurching ..also at that speed under load slightly lumpy...dont see coil packs as problem as it occurs when unloaded ANY ideas appreciated.....no codes at all ...would blocked injectors produce this symptom? |
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Title: Re: misfiring badly at 50 mph Post by lleewar on Sep 29th, 2011, 8:52pm How about a degenerating cat??? |
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Title: Re: misfiring badly at 50 mph Post by pedropedro on Sep 29th, 2011, 8:58pm new cat 6 mths ago..... but tks for suggestion |
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Title: Re: HELP misfiring badly at 50 mph Post by pedropedro on Oct 5th, 2011, 7:44am I would really be grateful for any ideas driving me nuts.......foot off or light throttle at 50-60 engines lurching missing ...there are no air leaks i can see..disconnect egr vac line..its still there ...it idles perfectly.drives perfectly up to 50 ish & after 60 its fine could it be injectors ? john |
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Title: Re: misfiring badly at 50 mph Post by Cosray on Oct 5th, 2011, 2:54pm Hi John - just following a hunch here - 1 how does she behave on cruise control at this critical speed? 2 Camshaft sensor not properly syncing? Ray |
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Title: Re: misfiring badly at 50 mph Post by pedropedro on Oct 5th, 2011, 3:12pm Ray...havent tried..why would that be any different ? john |
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Title: Re: HELP misfiring badly at 50 mph Post by Mike H on Oct 5th, 2011, 3:17pm on 10/05/11 at 07:44:29, pedropedro wrote:
No actually that's the exact opposite effect of (what was) my MAF problem, mine only did it under acceleration. Bad wiring gremlins again? |
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Title: Re: misfiring badly at 50 mph Post by Mike H on Oct 5th, 2011, 3:21pm Further to the above, Ray's mention of CPS reminds me the wiring to the camshaft sensor is part of that which can also be cooked along with the 'cut-off loom'; put it this way I had to rewire my CPS as well as the coil packs as the insulation had also gone hard and brittle there too. |
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Title: Re: misfiring badly at 50 mph Post by Cosray on Oct 5th, 2011, 3:39pm on 10/05/11 at 15:12:27, pedropedro wrote:
1 ... dunno - but since you've tried everything else... now the CKP and the CMP are being monitored for functionality by the CCM - CKP CHECK First, the relationship between PIP signals is evaluated to determine that the PIP signal is rational. Too large a change between 3 successive PIP indicates a noisy or missing PIP signal: P0320 Ignition/Distributor Engine Speed Input Circuit Malfunction Check the connection and wiring to the CKP sensor. Be prepared to replace this sensor. CMP CHECK Next, the CMP edge count is compared to the PIP edge count. If the proper ratio of CMP to PIP events is not being maintained (ie one CMP edge compared to 4 or 6 PIP events, depending on engine cylinders) it indicates a missing or noisy CMP signal: P0340 Camshaft Position Sensor Circuit Malfunction Check the connection and wiring to the CMP sensor. Be prepared to replace this sensor. There might be this critical speed (yours) at which the aged sensor does not quite cope... and confuses the ignition timing but not enough to create a DTC. Could be a bad connector as well resonating at a certain speed. 2 Is the phenomenon speed OR revs-related in other word can you reproduce the symptoms in another gear at the same revs? Ahhh 50-60 MPH in 3d or is it AUTO? is... HTH Ray |
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Title: Re: misfiring badly at 50 mph Post by pedropedro on Oct 5th, 2011, 3:42pm its speed related ...can shift into 3rd (its auto) and stay at 50 still does it .... have changed crankshaft sensor |
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Title: Re: misfiring badly at 50 mph Post by Cosray on Oct 5th, 2011, 3:45pm ... VSS OK? Had one before that was faltering also knocking out cruise control every now and then... Do you find that as well? Ray |
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Title: Re: misfiring badly at 50 mph Post by pedropedro on Oct 5th, 2011, 4:20pm no havent changed that ...if i hook up the obd reader and do a run can you plot the vss ? |
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Title: Re: misfiring badly at 50 mph Post by Cosray on Oct 5th, 2011, 4:34pm ... not being an expert I am certain that this all-important signal is available on OBD. A simple test would be - hence my CC question - to test the CC behaviour at the critical speed. In my case it would disconnect/disengage the CC because of bad signal and would not "lock" again. Culprit VSS. Ray |
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Title: Re: misfiring badly at 50 mph Post by pedropedro on Oct 5th, 2011, 6:57pm ive just done a run with vehicle explorer obd and something odd coming up when i play back..maf figures are ok at beginning ie .4 .7 etc then jumps to a reading of 4.9 7.2 then 11.1 intermitently ....shouldnt it run smoothly up to a max of maybe 1.2 at high revs ? if i am right wonder whats giving the high readings ...new maf unit ...that expains why it runs ok when i disconnect maybe....maybe ecu is at fault any thoughts or would you expect to see readings of 4.0 or higher at high acceleration?? |
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Title: Re: misfiring badly at 50 mph Post by Mike H on Oct 6th, 2011, 3:02pm The plot thickens! I don't think so see this page: http://www.fordscorpio.co.uk/mafdata.htm According that accepted range is 0 - 4.75V, personally I think it's still dodgy wiring or connectors, looks like 12V is jumping in from somewhere intermittently so may be a short somewhere or damp. Or could be the MAF sensor ground lead is going O/C. This is brand new MAF sensor so shouldn't be anything wrong with that. There's 4 wires to the MAF, I think 2 are for the heater element and the other 2 are the thermistor part. |
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Title: Re: misfiring badly at 50 mph Post by pedropedro on Oct 6th, 2011, 4:32pm well it must have 12v on the supply to the maf although output seems to be up to 5v or so......the ground measures 8r to battery which i guess is ok ish would expect to be zero need look at circuit and see where its grounded |
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Title: Re: misfiring badly at 50 mph Post by Mike H on Oct 6th, 2011, 6:34pm You might have to examine the wires from end to end, see what state they're in. Dodgy plug connector on the PCM box is another possbility (this happened to someone else just recently, was it the 24V that conked out and wouldn't restart from April?) |
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Title: Re: misfiring badly at 50 mph Post by Cosray on Oct 6th, 2011, 9:05pm Hi John, your ground resistance measured from MAF connector pin 3/Black to battery NEG pole must be a solid near-zero ohms on a Ohmsmeter in the 10 or max 100 ohms range. In an LHD the G10 ground distribution point sits next to the battery on the engine bulkhead -RHD may be different. If this point is rusty or oxidised it might create the funny values you are recording on the signalwires, making things go haywire. Try locating the crowded G10 point and wiggle it to see if the connection is "floating" and make your Ohms values fluctuate. Connector pin 5 is straight to the batt PLUS 12V on the Battreyr junction box C621 to Fuse F37, acc. to diagrams. Pin 1 & 2 signalwires lead to the PCM/EEC-V pins 36 & 88. Might be wise to inspect/cleanspray the big ECU multiplug as well and measure connectivity since cases of water intrusion have been reported. It sits under/behind the glovecompartment lid (remove) and can be retracted after removing one security rivet. HTH Ray |
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Title: Re: misfiring badly at 50 mph Post by pedropedro on Oct 7th, 2011, 7:35am Hello Ray thanks for that ..will work on that and figure why the ground is not zero rgds john |
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Title: Re: misfiring badly at 50 mph Post by Mike H on Oct 7th, 2011, 12:27pm Note also for a real chance of measuring very low resistances your meter probe tips must be absolutely clean and points of contact absolutely clean, double-check first that you can get a true zero between the probes themselves. (Analogue meters have a zero adjust, DMM's don't.) Aerosol switch contact cleaner is very useful in these cases. |
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Title: Re: misfiring badly at 50 mph Post by pedropedro on Oct 7th, 2011, 3:13pm Ok ground ok.......drove 100 miles today...with maf connected jerky lumpy and fuel consumption at steady 70 mph level ground was 25mpg...pulled maf pefectly smooth engine and consumption went to 38 mpg....when checking maf stationary looks fine on ve obd2 ....i am at a loss where to go now...it runs perfectly without maf so thats how i guess will have to run it without maf a mystery |
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Title: Re: misfiring badly at 50 mph Post by Cosray on Oct 7th, 2011, 3:30pm .... hmnmmm not encouraging... generally not employing the MAF should make things worse, not better... 1) ...do you still get this unusual 12V reading where 4,7V should be the max.? Pls confirm - That would explain why things are better w/o MAF . If so, following this reasoning, knowing your MAF is new AND assuming it's 100% THEN somewhere in the loom there's a voltage leak between some wires with brittle isolation and some humidity... not uncommon :( So IF this voltage leak is supposed to originate in the loom then you should be able to measure its presence (with a high resistance Voltmeter) at the MAF connector, at either pin 1 or 2 towards the EEC-V (since ground 3 nor 12V line 5 would be affected by leaks) with KEY ON and Engine running. 2) How did you measure the zero-Ohms-ground? I do hope between MAF connector pin 3 and Batt NEG pole? (thereby including discovery of a bad G10 Ground distribution) with Key ON engine running NO MAF? What do you think? Ray |
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Title: Re: misfiring badly at 50 mph Post by pedropedro on Oct 7th, 2011, 3:36pm Ray...where in the loom are there likely to be breaks ? ive had a fuel shut off loom fitted 12 mths ago...i will do a run with obd hooked up again.....yesterday i got some 11v and 7v readings so will work in that area..rgds john |
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Title: Re: misfiring badly at 50 mph Post by Cosray on Oct 7th, 2011, 4:06pm on 10/07/11 at 15:36:22, pedropedro wrote:
... impossible to say... with the 2.3 I am not sure... the usual suspect locations are close to Heat - causing isolation to brittle, come loose and cause crossleaks between arbitrary wires/strands... also looms affected by cooling lquid and oil... and heat. Over the top of the engine toward autobox, front of the engine, exhaust shield side of the engine are the worst sites. HTH Ray |
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Title: Re: misfiring badly at 50 mph Post by rich170361 on Oct 7th, 2011, 4:19pm I might be wrong I had a problem a bit like this on my cossie ultima changed the fuel pressure regulator has run fine ever since. |
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Title: Re: misfiring badly at 50 mph Post by Cosray on Oct 7th, 2011, 4:21pm Hi rich that's very plausible however it does not explain away the erratic MAF behaviour I am afraid... Ray |
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Title: Re: misfiring badly at 50 mph Post by pedropedro on Oct 7th, 2011, 4:32pm ive just run another scorpio with obd2 and the maf readings are the same as my one...ie accelerated hard up to 2700 rpm and maf reading went up to 8.7 on the the graph ..so despite the data page showing it going to 4.5 or so it seems it goes much higher....so i think red herring ...so now have to figure why it is lumpy at 50-60 with the maf plugged in and why fuel consumption doubles....beyond me for sure .....john |
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Title: Re: misfiring badly at 50 mph Post by Mike H on Oct 7th, 2011, 4:33pm Circuit diagram here, page 20 https://skydrive.live.com/?cid=eb36f845ea9b8fb6&id=EB36F845EA9B8FB6%21146# Seems MAF has electronics inside and uses +12V from fuse 37. Ground is via 'ground distribution, G10' which seems common to engine / transmission management, VSS etc. 2 separate wires go to PCM only brown/blue & white/blue. Have you looked at the actual PCM yet? Maybe water's got in and is messing with the plug block connections? The higher Voltage could be bridging across from another pin like Ray says, I still suspect something of that sort as well. Leccy gremlins! |
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Title: Re: misfiring badly at 50 mph Post by Mike H on Oct 7th, 2011, 4:39pm on 10/07/11 at 16:32:40, pedropedro wrote:
OK so boils down to what's the difference between closed loop & open loop fuelling, or, what else is not being used for open loop mode (?) EGR is one I believe.... |
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Title: Re: misfiring badly at 50 mph Post by pedropedro on Oct 7th, 2011, 4:40pm not convinced when maf disconnected goes to open loop...the lamdas still switch and seems to stay in closed loop |
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Title: Re: misfiring badly at 50 mph Post by Highlander on Oct 7th, 2011, 4:47pm New MAF faulty? Is the other Scorpio a 2.3? can you swap them temporarily? |
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Title: Re: misfiring badly at 50 mph Post by pedropedro on Oct 7th, 2011, 4:53pm ive done exactly that pulled that one and exchanged no difference i have x1 new , x1 from the other scorp and x2 others (x1 you sent me some while ago) all do the same thing......dont think its the maf ! so why does it run perfectly and fuel consumption low when maf pulled...the data readings i am convinced are fine........if it were a wiring short that would have produced symptoms with maf unplugged ? confused |
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Title: Re: misfiring badly at 50 mph Post by Mike H on Oct 7th, 2011, 4:55pm I'm only going by what I read on here, unless I remember it wrong, but something is different +MAF vs –MAF. Ah this is the page: http://www.fordscorpio.co.uk/maftest.htm |
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Title: Re: misfiring badly at 50 mph Post by Mike H on Oct 7th, 2011, 4:58pm See also about EGR, "My vehicle suffered from a persistent misfire under very light throttle conditions" http://www.fordscorpio.co.uk/egr.htm |
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Title: Re: misfiring badly at 50 mph Post by Cosray on Oct 7th, 2011, 5:16pm on 10/07/11 at 16:53:28, pedropedro wrote:
Yes that in itself is confusing however it could point to bad wiring which upsets the EEC-V as soon as the MAF is plugged IN and currents start flowing vice-versa. Pls do realise The EEC-V is a self-learning computer which adjusts itself constantly to a changing environment. Once you unplug the MAF the EEC-V could re-adjust and make the engine behave seemingly "better". HTH Ray |
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Title: Re: misfiring badly at 50 mph Post by Highlander on Oct 7th, 2011, 5:23pm Its running better with the MAF unplugged. So although its running better it still won't be running as good as it should be if everything were perfect. Therefore its either getting an incorrect reading from the MAF or what I think is more likely, the airflow the MAF is reporting is not what is actually going into the engine.. Air leaks behind the MAF, in the rubber hose/airbox? Seen the airboxes with holes in them and splits in the hoses When you tried it at 50mph in 3rd was that with the O/D button pressed? Try in in 2nd and see what happens |
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Title: Re: misfiring badly at 50 mph Post by pedropedro on Oct 7th, 2011, 5:34pm ok ..so maybe it doesnt go into complete open loop..all i know is the fuel consumption was low and smooth engine with it pulled |
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Title: Re: misfiring badly at 50 mph Post by pedropedro on Oct 7th, 2011, 5:39pm tried in 3 as thought maybe gearbox was culprit no diference...it only happens around 50-60 mph so havent been brave enough to try 2nd also checked everywhere for splits/holes around the box area...nothing i can see |
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Title: Re: misfiring badly at 50 mph Post by Tompion on Oct 7th, 2011, 7:02pm on 10/07/11 at 15:36:22, pedropedro wrote:
John The MAF isn’t wired via the cut off loom on the 2.3. What happens if you disconnect the vacuum tube to the top of the EGR & plug the tube – it won’t be able to go into closed loop. If the problem remains try disconnecting the plug on the EVR instead, to prevent closed loop (it’s located at the other end of vacuum hose to the EGR). As mentioned elsewhere are you sure the reading you see in the software is volts? |
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Title: Re: misfiring badly at 50 mph Post by pedropedro on Oct 7th, 2011, 8:09pm youre right re the maf numbers,,,i had assumed the numbers were volts ...guess theyre not i had locked myself into thinking that was the volt readout from the maf..... i am unclear why you want it to go into open loop what will that prove? i had disconnected the vac line to the egr and ran but didnt plug the hose....... can try that ...the valve does open cleanly can hear if i put a vac to the top of the valve is the egr side shut down if the maf is pulled ? unclear exactly what is disconnected/shut down if the maf isnt sending a signal |
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Title: Re: misfiring badly at 50 mph Post by Tompion on Oct 7th, 2011, 8:35pm It’s not that I want it to go into open loop, I thought it had been suggested the problem occurred when it went closed loop & that disconnecting the MAF prevented it going closed loop. I was suggesting keeping the MAF connected but preventing closed loop by other means. Obviously I misunderstood what was posted. |
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Title: Re: misfiring badly at 50 mph Post by pedropedro on Oct 7th, 2011, 8:48pm Dave....I must admit to being confused......in closed loop with maf connected its lumpy pull maf and its good... if you pull maf does it go into open loop ? thats what i dont understand. I am assuming because it runs so well with maf disconnected it must still be in closed loop ..my bad wording probably is cause of confusion apologies....... if maf is off is the egr disabled ??? john |
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Title: Re: misfiring badly at 50 mph Post by Tompion on Oct 7th, 2011, 11:58pm Not a problem, I just assumed open loop without the MAF was meant regardless of what may be written. Broadly speaking if everything is OK you shouldn’t notice any difference between closed & open loop. On this page: http://www.fordscorpio.co.uk/maftest.htm It says “In the case of a suspect MAF it is very easy to remove its influence and check the vehicle operation. Simply disconnect the MAF multiplug and then test drive the vehicle. The fuelling is now solely by RPM/ECT and if the noticed fault does not reoccur then the MAF is the culprit. NOTE: the fuelling is now in Open Loop - full LOS may not be experienced if other sensors are providing satisfactory data.” So open loop when disconnected, although I wouldn’t necessarily agree with “if the noticed fault does not reoccur then the MAF is the culprit”. I was suggesting that if it runs OK with the MAF plugged in but staying in open loop (by disabling the EGR) then the MAF may not be the problem. |
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Title: Re: misfiring badly at 50 mph Post by Tompion on Oct 8th, 2011, 12:31am I just looked back through the posts. The camshaft sensor was mentioned. It’s used for more precise fuelling but not essential, you could try disconnecting it – mine drives fine without it. |
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Title: Re: misfiring badly at 50 mph Post by pedropedro on Oct 8th, 2011, 8:55am Dave...ok understand a little better...I will reconnect maf and pull camshaft sensor...there is one other clue...engine has died couple of times maybe once every 200 miles when idling...have had crankshaft sensor changed and wiring between edis and ecu replaced...also cleaned idle valve....plugs good ....was going to change coil packs next ..thanks for advice appreciated But heres what i cant figure.. if by disconnecting any sensor it goes into open loop and then runs ok how can i isolate which sensor is bad? john |
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Title: Re: misfiring badly at 50 mph Post by pedropedro on Oct 8th, 2011, 10:26am open loop.../Dave i am very confused if i pull the maf the spark advance continues to alter it doesnt sit at 10 fixed..the fuel trims are changing ....sit around +/- 10 for stft ditto ltft ....so is it in open loop if those readings are changing ? when i connect maf stft goes up to + 10 and stays there pretty much ..? |
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Title: Re: misfiring badly at 50 mph Post by Mike H on Oct 8th, 2011, 11:22am Tompion beat me to it, yes the idea was to invoke open loop by something other than MAF unplugged. The way I understand it the EGR is used to deliberately make it run lean, but at the same time combustion chamber mustn't get too hot when doing that; so to maintain that kind of operation requires precise measurements of air flow etc., if it can't do that for any reason ('insufficient data') then the EGR is out of the game (can't be used). In other words unplugging the MAF prevent EGR being used, may still be an EGR related problem - your symptoms as described match that quite close apparently, see my link top of page. Or, noting "EDIS to ECU rewired", maybe we're starting to get a bit too bogged down in minutae; it could be much simpler, to quote Ray from elsewhere a while back the older these vehicles become the more wiring problems there will be, think it's coming down to examining the state of every wire with a magnifying glass or maybe thinking about replacing the whole engine loom with a good one to make sure. (?) Re the rewired EDIS this was the triple screened lead wasn't it? Makes me wonder if it was that bad what other wires are also screwed up. (?) Just thinking out loud |
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Title: Re: misfiring badly at 50 mph Post by Mike H on Oct 8th, 2011, 11:27am Afterthought ~ you could try soaking the whole wiring harness with WD40 see if that does anything, thinking in terms of water or damp ingress |
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Title: Re: misfiring badly at 50 mph Post by Cosray on Oct 8th, 2011, 12:48pm on 09/15/11 at 13:03:16, pedropedro wrote:
John Going back to your original post & complaint: everything fine but jerky at 50 mph. The problem is addictive and I am trying to do some eliminating from here. So in logical terms the change in behaviour arose after this particular job, is that observation correct? Was it perfectly running before the job? Good MPG, smooth running and shifting? If so, what caused you to do this job? Was there any other repair you did before the change in behaviour? "Now that was after a sorted wiring issue edis/ecu......... around EDIS." As I have done a few myself could you tell us what you did and how? Do you read/interprete electrical diagrams so I could drill deeper if needed? Curious, Ray |
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Title: Re: misfiring badly at 50 mph Post by pedropedro on Oct 8th, 2011, 2:14pm Ray....history as follows...car was running fine until one day it died....problem was the 3 core cable thats screened that runs between edis and ecu.....how do i know ?...took a week to start and by bending cable at edis end could invoke problem...stripped harness back found that cable & stripped... all wires rotten...all the other wires appeared to be ok but realise there is also wires to crankshaft sensor in that loom but seemed ok cut those x3 wires an inch or so from connector at edis ran new cable to ecu screened earthed at ecu etc .....all soldered properly ..good cable...and triple checked wiring correct pins etc ..yes went through wiring diagram started and ran immediately after that work...seemed ok but then noticed the lumpiness pulling back etc........ran car today without maf seems perfect |
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Title: Re: misfiring badly at 50 mph Post by Cosray on Oct 8th, 2011, 3:09pm Hi John, here's a pictureseries on a 24v suffering from rotten engine compartment wiring harness. That's the main one from the EEC-V to the front, all ABS Module and sensors, EDIS, and the two cubic connectors leading to the engine/autobox loom ("cut-off loom") and containing perhaps the MAF-wiringset of 4 as well. Also it contains signals of almost all sensors such as camshaft, throttle position, VSS and other autobox sensors and valves, Injectors, Idle Valve, ACT etc. etc. NOT Crankshaft Position Sensor since that communicates directly with EDIS. http://bit.ly/rdxQ9r Tompion further up was of the opinion it is not contained in the main loom. "John The MAF isn’t wired via the cut off loom on the 2.3. ". If that is the case it should be easier to follow and inspect and perhaps repair. Anyway, the engine compartment loom contains the shielded 3-wire loom between EDIS and EEC-V, containing the IDM, PIP and Sparkadvance signals, separately wrapped and rotten as well. I also cut & bypassed it with a new cable which worked fine. However, more in the big loom was rotten (see pics) so in the end I found a good loom in Germany. The bad spot in my case was next to the exhaustpipe, add some oil and coolant and poooof. Only thing I can think of right now is the changed grounding location G7 of the cable shield. If wrongly grounded it could induce eddycurrents upsetting the system. My TIS0009 for 2.3 says ": G7, LH A-pillar, RHD". Do you have the TIS CD? If not I could upload it to your emailaddress; let me know. In any case it should be grounded at ONE spot only so either near the EDIS, or G7, or around the EEC-V. HTH Ray |
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Title: Re: misfiring badly at 50 mph Post by Mike H on Oct 8th, 2011, 3:39pm Think this is more like it, given the rotten 3-core business it would make me suspicious of what other bad wires there may be. Plus ditto re 3-core screen |
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Title: Re: misfiring badly at 50 mph Post by Tompion on Oct 8th, 2011, 7:05pm on 10/08/11 at 10:26:51, pedropedro wrote:
John. I shouldn’t worry about that, mine goes just as well without the MAF as with it, it’s certainly not in any sort of limp mode. Closed loop is about controlling emissions by cooling combustion, if it stays open loop that in itself shouldn’t affect performance. The status page on your software should tell you if it’s open loop, or you can look at the enhanced window of the data tab. Have you checked for codes on the enhanced window as well as on the codes tab? You could try recording the outputs of sensors like ECT, IAT, MAF, BARO on a level road at a steady speed with the misfire occurring to see if any readings are fluctuating (which may cause the EGR to adjust incorrectly). If you decide to spray the loom as Mike said I’d suggest trying Corrosion Block: http://www.flyingshop.com/corrosion-block-aerosol-12oz/ Someone on the mailing list has had good results with it. Rather than disturb the loom, he just sprayed plenty of it onto the taped up areas. Clearly it won’t help with direct shorts but may help stop tracking via damp, road salt etc. |
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Title: Re: misfiring badly at 50 mph Post by Mike H on Oct 8th, 2011, 7:56pm on 10/08/11 at 19:05:43, Tompion wrote:
Good thinking Batman http://livinginthepast-audioweb.co.uk/images/misc/th_thumbsup.gif |
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Title: Re: misfiring badly at 50 mph Post by Mike H on Oct 13th, 2011, 3:17pm How are we getting on with this? |
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Title: Re: misfiring badly at 50 mph Post by pedropedro on Oct 14th, 2011, 6:17pm found split hose on one of the egr connections....not sure if it sorted but got the impression seemed better on the short run i took it on, but have had to go away on business...back in 2 weeks so will be able to investigate then would make sense if the dumping of exhaust gasses into the inlet wasn't doing its thing correctly |
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Title: Re: misfiring badly at 50 mph Post by Cosray on Oct 14th, 2011, 6:30pm Hi John - which hose pls? Was it on of the two hoses/tubes running off the Diff Sensor towards the two pipes from the venturi behind the engine? Curious, Ray |
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Title: Re: misfiring badly at 50 mph Post by pedropedro on Oct 14th, 2011, 7:03pm Hi Ray yes the x2 rubber hoses from the transducer go into the heat shield and at that point connect onto x2 metal tubes going to the venturi...i went to pull the top one off and it fell off in my hand....it had been rubbing on the lower connector and had split underneath..separated the pipework refitted and got impression problem had gone ,,,but just short test drive ...will test thoroughly in 2 weeks time |
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Title: Re: misfiring badly at 50 mph Post by Tompion on Oct 14th, 2011, 7:48pm You may do better to replace them, although mine looked OK they just kept splitting again. I used some high pressure petrol hose. |
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Title: Re: misfiring badly at 50 mph Post by pedropedro on Oct 14th, 2011, 8:36pm good idea...will do that when I am back..tks for tip |
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Title: Re: misfiring badly at 50 mph Post by Mike H on Oct 15th, 2011, 10:09am Ah-ha!! It's all making sense .. http://livinginthepast-audioweb.co.uk/images/misc/umm_scratches_chin.gif Air leak in EGR hosing, so EGR valve won't work properly. Because EGR won't work as it's supposed to, strange driving behaviour. Stop EGR being used by pulling MAF plug, car appears to behave more normally. I also note "engine has died couple of times" I guess it could if hose leak has opened inlet manifold to atmosphere, as ultimately that's where the vacuum comes from. Tip for the future then as pedropedro has proved ~ cursory looks at vacuum hoses not good enough, need to take off for a more thorough butchers. This could have been solved in 10 minutes if only you knew what you were looking for. ;D Yep I agree treat yourself so some new hose pipe. Local motor factors should have something, just need the diameter. |
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Title: Re: misfiring badly at 50 mph Post by Tompion on Oct 15th, 2011, 10:41am I minor leak on the exhaust side may allow air to enter the exhaust causing the oxygen sensor to richen the mix. With a leak there when the EGR is commanded open the DPFE may receive false information causing the EGR to open more or less than it should. |
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Title: Re: misfiring badly at 50 mph Post by Cosray on Oct 15th, 2011, 9:25pm Hi all - just for kicks I tried to replicate Jonh's car's behaviour and mine of some years ago. I pulled one each of the EGR Differentail Pressure Sensor's hoses. The open one could be felt huffin' and puffin'. I am not sure which EGR Diff tube it was, the lower one near the exhaust or the upper one over the venturi. Both huffed and puffed equally. No bad signs though on all speeds. Put the hoses back on, pulled the connector of the EGR Diff sensor slightly loose and that made the engine hesitate at light throttle and around 100 kmh, especially on Cruise Control I could feel the control unit try to cope with the unusual sitaution. Perhaps on a 24v it's different? I should have taken off the MAF's connector for test; will do later this week. HTH Ray |
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Title: Re: misfiring badly at 50 mph Post by Mike H on Oct 16th, 2011, 11:57am Top research http://livinginthepast-audioweb.co.uk/images/misc/th_thumbsup.gif So could still be dodgy wiring / connector problem |
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