981 misfire and useless OPC
Discussion
My local OPC changed the spark plugs in my 981 at the correct age/mileage and the car had a new coil pack under warranty some time ago after going into limp home mode, it’s now since developed a misfire which is present from idle all the way up to 4500rpm.
As the car is under warranty I took it to an OPC who agreed they could feel it but said it was normal and that it was the car “coming on cam” which I think is absolute rubbish, unless these cars come on cam 10 times from idle and 4500rpm…
I’ve then took it to another OPC who agrees they can feel it but they can’t replace anything under warranty because the computer doesn’t report any error codes, so as far as they are concerned there is no fault.
I’m really getting frustrated now, the car isn’t nice to drive and I really want it fixing. If it were any normal car I’d just buy some new spark plugs and ignition packs and do it myself but I begrudge going through the expense and effort when I’ve paid a lot of money for a 2-year warranty that has evaporated the moment I tried to claim on it.
I can’t sell the car privately with a misfire, and my OPC won’t give me market value in a part ex until its fixed yet their own service desk are shrugging their shoulders.
Any advice would be appreciated.
As the car is under warranty I took it to an OPC who agreed they could feel it but said it was normal and that it was the car “coming on cam” which I think is absolute rubbish, unless these cars come on cam 10 times from idle and 4500rpm…
I’ve then took it to another OPC who agrees they can feel it but they can’t replace anything under warranty because the computer doesn’t report any error codes, so as far as they are concerned there is no fault.
I’m really getting frustrated now, the car isn’t nice to drive and I really want it fixing. If it were any normal car I’d just buy some new spark plugs and ignition packs and do it myself but I begrudge going through the expense and effort when I’ve paid a lot of money for a 2-year warranty that has evaporated the moment I tried to claim on it.
I can’t sell the car privately with a misfire, and my OPC won’t give me market value in a part ex until its fixed yet their own service desk are shrugging their shoulders.
Any advice would be appreciated.
Edited by SkinnyPete on Saturday 3rd November 21:54
Thanks for that Steve.
I'm pretty sure they said they checked the fuelling but I will ask them to see if they can check the emissions. In terms of vibration, what would you have in mind?
Having said all that, the fact you can hear the exhaust note missing slightly at idle and based on past experiences it still seems like a classic case of spark plugs/ignition coils. The Porsche technicians are adamant that if it were a misfire it would show on the diagnostics but I don't see how this is possible, unless there was a catastrophic breakdown somewhere.
If I don't get anywhere with Porsche then the alternative is I spend £400 on ignition packs and spark plugs, but I really want to avoid going down this route as I've read the 2 cylinders nearest the bulkhead are a pain to change. In fact the cynical side of me would suggest Porsche probably didn't even change the spark plugs...
Edited just to add, your comments about compression...if this were the case would oil consumption not be high? The car uses none.
I'm pretty sure they said they checked the fuelling but I will ask them to see if they can check the emissions. In terms of vibration, what would you have in mind?
Having said all that, the fact you can hear the exhaust note missing slightly at idle and based on past experiences it still seems like a classic case of spark plugs/ignition coils. The Porsche technicians are adamant that if it were a misfire it would show on the diagnostics but I don't see how this is possible, unless there was a catastrophic breakdown somewhere.
If I don't get anywhere with Porsche then the alternative is I spend £400 on ignition packs and spark plugs, but I really want to avoid going down this route as I've read the 2 cylinders nearest the bulkhead are a pain to change. In fact the cynical side of me would suggest Porsche probably didn't even change the spark plugs...
Edited just to add, your comments about compression...if this were the case would oil consumption not be high? The car uses none.
From what you say the ECU certainly seems smart enough, but is it infallible?
If it were a vibration then why would it disappear above 4500rpm and why would it be so random? If I keep a light throttle at low revs I can get away with it but anything more than that then it rears its head, some days are worse than others.
I had a long journey last week and my passenger had their head in their hands thinking the car is going to break down, yet later on it was hardly noticeable. I've yet to find a trend or pattern.
If it were a vibration then why would it disappear above 4500rpm and why would it be so random? If I keep a light throttle at low revs I can get away with it but anything more than that then it rears its head, some days are worse than others.
I had a long journey last week and my passenger had their head in their hands thinking the car is going to break down, yet later on it was hardly noticeable. I've yet to find a trend or pattern.
nw942 said:
If the actuator in the exhaust was stuck in a partially open state, would that cause these symptoms?
I wouldn't have thought so but my car does not have PSE so does it even have an actuator? pete.g said:
Have you ruled out a faulty hydraulic lifter?
No, how would one diagnose/test that? Steve H said:
JensonBGTS said:
I had this following a service and plug change to my 987.2 at an independent, I returned the car and all coil packs were changed but fault still persisted so I took the car to an OPC where it was found the plugs as fitted were of shorter reach from 987.1. Correct plugs fitted and OPC billed the independent.
That's an interesting one. OP, did your symptoms start immediately after the service at the OPC? I have seen symptoms like this from a plug being fitted with the gap closed up but again if it was only on one cylinder I would have expected it to flag a light - if they were all incorrect or gapped wrong it's possible the ecu would have a harder time picking up on it??
I'm going to have another crack at my OPC but failing that I'll change plugs and coils myself and I'll bet a months salary it fixes the issue.
AW10 said:
Worth a read? http://www.boxa.net/forum/topic/73120-read-this-if...
Very interesting thanks for that. I wonder how difficult one is to fit.TrackNutz said:
Why the hell were only 4 replaced?
Reading your first post the spark plug length sprung to mind, I've seen this a few times before, it's been mentioned a few times above but I can personally vouch for it causing rough running without the DME throwing a misfire code, it does however show a difference in the cylinder roughness AV's. Still, no codes show up.
Try that first. If you know the spark plug part numbers from your invoice, message them across and I'll check them.
999.170.151.90 is what is on my invoice but you never know they could have fitted different ones.Reading your first post the spark plug length sprung to mind, I've seen this a few times before, it's been mentioned a few times above but I can personally vouch for it causing rough running without the DME throwing a misfire code, it does however show a difference in the cylinder roughness AV's. Still, no codes show up.
Try that first. If you know the spark plug part numbers from your invoice, message them across and I'll check them.
I can't prove only 4 were replaced but my point was, mechanics sometimes get lazy when they think they can get away (especially when they get a bonus for completing jobs early, which they do at Porsche) with it and 2 out of the 6 plugs are difficult to change. So maybe they didn't bother and hence said plugs are now worn out.
I took the car to a well respected Porsche independent and they agreed they could feel exactly what I was talking about. Unfortunately their computer too said everything was fine, ignition, fuel etc.
They said have a go at replacing coils etc but I could just potentially be throwing money down the drain.
I then tried another OPC who had the car for two days, the best they did was reset the ECU and PDK ECU.
I’ll have to be honest it did seem to make an improvement although it wasn’t perfect, however as a few weeks past it’s back to how it was.
They’re taking another look soon, but this time I’ve asked them to liaise with Porsche Germany until the car is fixed.
They said have a go at replacing coils etc but I could just potentially be throwing money down the drain.
I then tried another OPC who had the car for two days, the best they did was reset the ECU and PDK ECU.
I’ll have to be honest it did seem to make an improvement although it wasn’t perfect, however as a few weeks past it’s back to how it was.
They’re taking another look soon, but this time I’ve asked them to liaise with Porsche Germany until the car is fixed.
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