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Topic: misfiring badly at 50 mph (Read 7331 times) |
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pedropedro
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misfiring badly at 50 mph
« Reply #20 on: Sep 24th, 2011, 5:05pm » |
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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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pedropedro
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Re: misfiring badly at 50 mph
« Reply #22 on: Sep 24th, 2011, 5:38pm » |
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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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Mike H
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Renault Clio
 
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Re: misfiring badly at 50 mph
« Reply #23 on: Sep 25th, 2011, 12:45pm » |
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I presume closed-loop fuelling (MAF unplugged, engine cold etc.) also means EGR is not used.
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Mike H
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pedropedro
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Re: misfiring badly at 50 mph
« Reply #24 on: Sep 25th, 2011, 12:48pm » |
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thats a good point ....
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Mike H
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Renault Clio
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Re: misfiring badly at 50 mph
« Reply #25 on: Sep 25th, 2011, 1:02pm » |
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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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Mike H
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Mike H
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Renault Clio
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Re: misfiring badly at 50 mph
« Reply #26 on: Sep 25th, 2011, 1:06pm » |
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on Sep 25th, 2011, 12:48pm, pedropedro wrote:
I thought so too ... 
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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Mike H
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pedropedro
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Posts: 677
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Re: misfiring badly at 50 mph
« Reply #27 on: Sep 28th, 2011, 2:03pm » |
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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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leewar
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I'm a YaBB newbie!
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Re: misfiring badly at 50 mph
« Reply #28 on: Sep 29th, 2011, 8:52pm » |
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How about a degenerating cat
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pedropedro
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Posts: 677
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Re: misfiring badly at 50 mph
« Reply #29 on: Sep 29th, 2011, 8:58pm » |
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new cat 6 mths ago..... but tks for suggestion
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pedropedro
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Posts: 677
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Re: HELP misfiring badly at 50 mph
« Reply #30 on: Oct 5th, 2011, 7:44am » |
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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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Cosray
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8th Scorpio, 2nd Cosworth: currently '95
Posts: 569
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Re: misfiring badly at 50 mph
« Reply #31 on: Oct 5th, 2011, 2:54pm » |
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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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pedropedro
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Posts: 677
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Re: misfiring badly at 50 mph
« Reply #32 on: Oct 5th, 2011, 3:12pm » |
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Ray...havent tried..why would that be any different ? john
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Mike H
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Renault Clio
Posts: 2594
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Re: HELP misfiring badly at 50 mph
« Reply #33 on: Oct 5th, 2011, 3:17pm » |
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on Oct 5th, 2011, 7:44am, pedropedro wrote:| .......foot off or light throttle at 50-60 engines lurching missing ... |
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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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Mike H
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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 #34 on: Oct 5th, 2011, 3:21pm » |
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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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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 #35 on: Oct 5th, 2011, 3:39pm » |
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on Oct 5th, 2011, 3:12pm, pedropedro wrote:| Ray...havent tried..why would that be any different ? john |
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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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pedropedro
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Posts: 677
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Re: misfiring badly at 50 mph
« Reply #36 on: Oct 5th, 2011, 3:42pm » |
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its speed related ...can shift into 3rd (its auto) and stay at 50 still does it ....
have changed crankshaft sensor
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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 #37 on: Oct 5th, 2011, 3:45pm » |
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... 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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pedropedro
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Posts: 677
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Re: misfiring badly at 50 mph
« Reply #38 on: Oct 5th, 2011, 4:20pm » |
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no havent changed that ...if i hook up the obd reader and do a run can you plot the vss ?
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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 #39 on: Oct 5th, 2011, 4:34pm » |
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... 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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