misfire
#21
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About 50mph uphill seems to be a harsh test
The 4.0 and original 3.0 (pre-2003) have a different OBD system (PCM is Visteon) via SCP (aka J1850 PWM). Later cars have Denso via CAN/ISO. Doesn't matter with most OBD tools but some cheap ones don't like something about the Visteon. But they tend not to communicate - they don't wrongly say no codes.
The 4.0 and original 3.0 (pre-2003) have a different OBD system (PCM is Visteon) via SCP (aka J1850 PWM). Later cars have Denso via CAN/ISO. Doesn't matter with most OBD tools but some cheap ones don't like something about the Visteon. But they tend not to communicate - they don't wrongly say no codes.
The reason I ask about the different versions is that I do not think or I read that the old version you notated does not report throttle body issues and if nothing esle has shown a code, perhaps it is one that does not get reported, although back to the dealer issue and whether you can trust what they say. I have had enough outright lies and damage coverups by them- I just now assume a lie.
Tom in Dallas
#22
#23
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Took my 2001 S type 4.0 to the dealer today for a diagnosis of the misfire at idle.
Dealer said that it had no codes and gave me an estimate of $1,600 for new coils and plugs.They charged me $107.00 for the diagnosis.The service man and mechanic said to drive it until a light comes on and then they can read the code.I asked if it would harm the catalytic converters to drive it.Their answer was no.Said it would have to have a very bad miss and be driven for a long time before any damae the cats.
I have taken it to three shops and all have said the same.Apparently they cant diagnose a problem unless they can read a code.Alternative is to spend lots of money and hope they find the problem
I think I will continue to drive it until I get a better diagnosis than I have had so far.
I will inform you when and if I solve the puzzle.
Dealer said that it had no codes and gave me an estimate of $1,600 for new coils and plugs.They charged me $107.00 for the diagnosis.The service man and mechanic said to drive it until a light comes on and then they can read the code.I asked if it would harm the catalytic converters to drive it.Their answer was no.Said it would have to have a very bad miss and be driven for a long time before any damae the cats.
I have taken it to three shops and all have said the same.Apparently they cant diagnose a problem unless they can read a code.Alternative is to spend lots of money and hope they find the problem
I think I will continue to drive it until I get a better diagnosis than I have had so far.
I will inform you when and if I solve the puzzle.
I agree with Jagv8, I would find a hill, start at zero and push all the way to the floor and get up to about 100mph on a hot day. It it carries the load, then I would have a hard time thinking it was the coils..
If you consider al that makes for proper combustion and only at a low speed, then something is having problems with a spark (such as a wire that could be stretched and strands broken and shows not enough juice at lower rpm) or one of the fuel injectors is partially restricted, but not enough to show an injector fault and these injectors I understand are fairly bullet proof, but age can cause buildup. Or you have a throttle position sensor that might be throwing a problem at lower rpm. Just random thoughts. If the dealer could not find anything and you can believe them (their software should show if any one cylinder had too many misfire as it runs a count of all misfires- did you get a print out from them?)- then you are having some weird combustion problem- even at the age- could be a simple as fuel filter- but doubtful
Other than misfires at idle- do you have a rough idle? (discounting anything caused by the ac compressor) If you turn the ac off, do you still get misfires?
Tom In Dallas/Plano
#24
#25
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I am suggesting this as it was the only time other than idle that I developed a misfire initially. My symptoms started just like his for all intents and purposes. If he cannot get codes at idle and if he does a WOT at a higher speed and pushing the load of the engine and yes the pcm and does not get them, then he knows to look elsewhere. He needs to put as heavy a load as possible. Im ,y case it was a crimped and parted wire and I got the problem when I came off a heavy speed or had the load on the car near top or at idle- however it did force the showing of codes and pre-ignitation sounds. I just trying to suggest what several Jag techs (now gone from the ***********) have suggested to try and force an error. This can actually get scary when driving along in heavy freeway traffic at an even speed of 70mph and have it slip in to RP for no good reason.
Have you done an extensive wiggle wire test in an organized fashion around the engine?
Tom in Dallas
Last edited by jazzwineman; 09-05-2014 at 09:30 AM.
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oldmaned (09-05-2014)
#26
#27
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Mine was a wire, hidden away, that normally would not be seen and since it came plastic wrapped from the factory the crimp that was found had to come from the factory and it took this many years to fray and come apart on the inside of the wire- not seen from the outside.
Tom in Dallas
Tom in Dallas
#28
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I haven't tried the acceleration test uphill but it will rev to 6,500 rpm's and not miss.I am sure it would rev to the redline but I haven't tried that.
Yes,I have wriggled,pushed and pulled every wire and connection I can see under the hood.I have driven it twice since the trip to the dealer and it is the same or possibly a little improved.Misses only at idle and occasionaly low speeds.The misfire is intermittent and not constant as it will misfire,idle normal and then again a misfire.
I will continue to drive it until it gets worse and locate some coils and plugs and have them installed soon.I know how to do it but my old back and poor eyes make it difficult.
Thanks again for the responses.
Yes,I have wriggled,pushed and pulled every wire and connection I can see under the hood.I have driven it twice since the trip to the dealer and it is the same or possibly a little improved.Misses only at idle and occasionaly low speeds.The misfire is intermittent and not constant as it will misfire,idle normal and then again a misfire.
I will continue to drive it until it gets worse and locate some coils and plugs and have them installed soon.I know how to do it but my old back and poor eyes make it difficult.
Thanks again for the responses.
#29
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Bought an OBD2 code reader and read the codes on my SType.Actually,I did not read the codes as the reader indicated no codes stored.
It still has an intermittent miss at idle but speeds above idle ,the engine runs very smooth.
I will take it to Jag dealer if the misfire continues at idle.
Thanks for the responses.
It still has an intermittent miss at idle but speeds above idle ,the engine runs very smooth.
I will take it to Jag dealer if the misfire continues at idle.
Thanks for the responses.
I guess my next action will be to replace the coils and plugs.The car has 60,000 miles .
Any suggestions will be appreciated.
#30
#31
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My 2001 stype 4.0 still has a misfire and no codes.I have driven it about 3,000 miles since misfire started several European mechanics and Jag dealer can't diagnose the problem because it shows no codes.The misfire continues to get a little worse but still very drivable.
I guess my next action will be to replace the coils and plugs.The car has 60,000 miles .
Any suggestions will be appreciated.
I guess my next action will be to replace the coils and plugs.The car has 60,000 miles .
Any suggestions will be appreciated.
Do the misfires ever seem to sound like internal denotations especially under load or heavier acceleration? That could be the sound of a cat backing up. Are you getting a particular noxious smell coming from the car like un-burned gas or higher than normal combustion smells?
Did you ever see a flashing check engine light?
The Jag dealer can get into the back door of the computer system and look at the misfires on each cylinder.
I think you may have a coil or plug problem or water and oil leaking into the area, but why it will not show the codes is beyond me. Have you tried the simple 3 minute job of cleaning the Mass Air Flow Sensor and see if any change?
I had severe misfire problem that came from the trigger wire of the #3 and 5 cylinder. Because of the way it was crimped and covered with plastic, I happen to think it came from the factory that way and finally heat and time caused the on and off separation and misfires. But I had codes and a flashing CEL on all of this
Good Luck
Tom in Plano 05 S-type 3.0 92k
#32
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We've had quite a few blocked/damaged cats that didn't throw any P0420/P0430 or the like codes. Some (maybe all) had odd fuel trims, since the air/exhaust flow is affected especially under load.
Another possibility if you have not had the chain tensioners replaced would be timing being off. That sooner or later leads to engine destruction so be sure...
Another possibility if you have not had the chain tensioners replaced would be timing being off. That sooner or later leads to engine destruction so be sure...
#33
#34
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Tom in Dallas
#35
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Jag indy if you prefer but costs more money.
#36
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Hope this gives you a better understanding.
Tom in Dallas
#37
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It's good. Oddly though it's a FAQ on this site it seems not too easy to find https://www.jaguarforums.com/forum/g...ed-quiz-49317/
There's at least one more useful item in the FAQ.
There's at least one more useful item in the FAQ.
#39
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Run at idle and look at short term and long terms, then go to 2500 rpm and do the same.
You should see if it is happening to both sides or just one and if lean or rich. If you post the trims, there are plenty of us that can help to interpret. Make sure the fuel system show closed and not open or that might indicate an 02 sensor problem.
Tom in Dallas/Plano
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