986 2.7 lumpy idle (with error codes)
Discussion
History first... bought my 2000 Boxster 2.7 last summer; haven't done many miles since then. The idle recently got really lumpy, and an inspection revealed there was a split in the oil seperator pipework - as per this picture:
I replaced that pipe, and the idle instantly restored itself to normality! I had also cleaned the throttle body:
Today though, I got hold of a Durametric, and read the codes stored (the engine light had been on for a while):
I deleted these codes, then the car stalled. I restarted it, but it's really lumpy again when starting first - then it smooths out somewhat. It's showing sporadic misfires in cylinders 3, 5 and sometimes 6 - but very sporadic & no fault codes generated (that was from live running data). It's almost as if I've wiped any adaptations that were stored on the ECU, and it's relearning - but I don't know if there's any validity in that statement. I could still have an air leak I suppose, although no codes have reappeared.
Any ideas what my next steps are here? All suggestions appreciated.
I replaced that pipe, and the idle instantly restored itself to normality! I had also cleaned the throttle body:
Today though, I got hold of a Durametric, and read the codes stored (the engine light had been on for a while):
I deleted these codes, then the car stalled. I restarted it, but it's really lumpy again when starting first - then it smooths out somewhat. It's showing sporadic misfires in cylinders 3, 5 and sometimes 6 - but very sporadic & no fault codes generated (that was from live running data). It's almost as if I've wiped any adaptations that were stored on the ECU, and it's relearning - but I don't know if there's any validity in that statement. I could still have an air leak I suppose, although no codes have reappeared.
Any ideas what my next steps are here? All suggestions appreciated.
Thanks. I'll get into the engine next weekend.
On the misfire, I don't have any error codes, but the misfire count on the live data was showing the occasional trigger. Very seldom, but present.
I removed the MAF and cleaned it recently, but I might give this another go. The car has a Pipercross filter that I think has been over-oiled, so this needs to go too to be eliminated (I've never been a fan of such filters, as that subsequent washing & oiling is frequently overdone).
On the misfire, I don't have any error codes, but the misfire count on the live data was showing the occasional trigger. Very seldom, but present.
I removed the MAF and cleaned it recently, but I might give this another go. The car has a Pipercross filter that I think has been over-oiled, so this needs to go too to be eliminated (I've never been a fan of such filters, as that subsequent washing & oiling is frequently overdone).
As Cmoose says, I would be tempted to try the MAF sensor especially if the AOS has been failing.
Alternatively/additionally, have you reset the eGas since cleaning the TB? I have an old cable throttle car but I have heard that the eGas throttle position sensor sometimes need resetting. Might explain the lumpy idle...
Good luck!
Alternatively/additionally, have you reset the eGas since cleaning the TB? I have an old cable throttle car but I have heard that the eGas throttle position sensor sometimes need resetting. Might explain the lumpy idle...
Good luck!
Edited by LennyM1984 on Friday 7th June 14:40
LennyM1984 said:
As Cmoose says, I would be tempted to try the MAF sensor especially if the AOS has been failing.
Alternatively/additionally, have you reset the eGas since cleaning the TB? I have an old cable throttle car but I have heard that the eGas throttle position sensor sometimes need resetting. Might explain the lumpy idle...
Good luck!
That's a new one on me - must google that procedure.Alternatively/additionally, have you reset the eGas since cleaning the TB? I have an old cable throttle car but I have heard that the eGas throttle position sensor sometimes need resetting. Might explain the lumpy idle...
Good luck!
Cheers.
BFleming said:
LennyM1984 said:
Thank you!Very important to re set the TB after cleaning, do that (vids online, very easy to do) and have another go, could be the 02 sensors though, i have had to change all 4 of mine and they are expensive at an indy as they can require extra work to get them out and Porsche units are expensive.
Thread revival. The CEL was coming back on periodically, so I ended up buying a new MAF. The car pulls and idles a lot better - but the CEL keeps coming back on every so often, P1128 & P1130 are the codes that appear each time. O2 sensors next I guess 
On the plus side, a clean car is a happy car!
On the plus side, a clean car is a happy car!
Edited by BFleming on Monday 13th January 09:45
Gassing Station | Boxster/Cayman | Top of Page | What's New | My Stuff