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Topic: misfiring badly at 50 mph (Read 7335 times) |
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Mike H
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Renault Clio
  
Posts: 2594
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Re: misfiring badly at 50 mph
« Reply #60 on: Oct 7th, 2011, 4:58pm » |
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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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Mike H
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Cosray
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8th Scorpio, 2nd Cosworth: currently '95
Posts: 569
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Re: misfiring badly at 50 mph
« Reply #61 on: Oct 7th, 2011, 5:16pm » |
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on Oct 7th, 2011, 4:53pm, pedropedro wrote: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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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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Highlander
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Expert
13 Scorpios, XR4x4, Suzuki SJ413 for off road :)
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Re: misfiring badly at 50 mph
« Reply #62 on: Oct 7th, 2011, 5:23pm » |
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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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on Oct 17th, 2011, 12:35pm, Simmo wrote:I give up !  Too much for an old boy!  |
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pedropedro
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Posts: 677
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Re: misfiring badly at 50 mph
« Reply #63 on: Oct 7th, 2011, 5:34pm » |
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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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pedropedro
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Posts: 677
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Re: misfiring badly at 50 mph
« Reply #64 on: Oct 7th, 2011, 5:39pm » |
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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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Tompion
Administrator
1997 2.3 Ultima estate.
Posts: 2918
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Re: misfiring badly at 50 mph
« Reply #65 on: Oct 7th, 2011, 7:02pm » |
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on Oct 7th, 2011, 3:36pm, pedropedro wrote:| 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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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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ABS multiplug wheel sensor pins MK IV or MK 20
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pedropedro
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Posts: 677
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Re: misfiring badly at 50 mph
« Reply #66 on: Oct 7th, 2011, 8:09pm » |
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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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Tompion
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1997 2.3 Ultima estate.
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Re: misfiring badly at 50 mph
« Reply #67 on: Oct 7th, 2011, 8:35pm » |
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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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ABS multiplug wheel sensor pins MK IV or MK 20
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pedropedro
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Posts: 677
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Re: misfiring badly at 50 mph
« Reply #68 on: Oct 7th, 2011, 8:48pm » |
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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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Tompion
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1997 2.3 Ultima estate.
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Re: misfiring badly at 50 mph
« Reply #69 on: Oct 7th, 2011, 11:58pm » |
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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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ABS multiplug wheel sensor pins MK IV or MK 20
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Tompion
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1997 2.3 Ultima estate.
Posts: 2918
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Re: misfiring badly at 50 mph
« Reply #70 on: Oct 8th, 2011, 12:31am » |
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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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ABS multiplug wheel sensor pins MK IV or MK 20
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pedropedro
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Posts: 677
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Re: misfiring badly at 50 mph
« Reply #71 on: Oct 8th, 2011, 8:55am » |
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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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pedropedro
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Re: misfiring badly at 50 mph
« Reply #72 on: Oct 8th, 2011, 10:26am » |
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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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Mike H
Senior Member
Renault Clio
Posts: 2594
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Re: misfiring badly at 50 mph
« Reply #73 on: Oct 8th, 2011, 11:22am » |
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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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Mike H
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Mike H
Senior Member
Renault Clio
Posts: 2594
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Re: misfiring badly at 50 mph
« Reply #74 on: Oct 8th, 2011, 11:27am » |
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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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Mike H
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Cosray
Full Member
8th Scorpio, 2nd Cosworth: currently '95
Posts: 569
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Re: misfiring badly at 50 mph
« Reply #75 on: Oct 8th, 2011, 12:48pm » |
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on Sep 15th, 2011, 1:03pm, pedropedro wrote: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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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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pedropedro
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Posts: 677
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Re: misfiring badly at 50 mph
« Reply #76 on: Oct 8th, 2011, 2:14pm » |
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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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Cosray
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8th Scorpio, 2nd Cosworth: currently '95
Posts: 569
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Re: misfiring badly at 50 mph
« Reply #77 on: Oct 8th, 2011, 3:09pm » |
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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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Mike H
Senior Member
Renault Clio
Posts: 2594
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Re: misfiring badly at 50 mph
« Reply #78 on: Oct 8th, 2011, 3:39pm » |
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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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Mike H
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Tompion
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1997 2.3 Ultima estate.
Posts: 2918
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Re: misfiring badly at 50 mph
« Reply #79 on: Oct 8th, 2011, 7:05pm » |
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on Oct 8th, 2011, 10:26am, pedropedro wrote: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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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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