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Looking for possible ideas on what could be cause:
Car drivers normal until Revs reach 5k RPM (so thinking 2nd turbo related) under hard pull (close to WOT) lasting only a few seconds.
CEL comes on shortly after coming off throttle and revs falling back < 4k.
I just got it back from a CEL diagnosis, repair, and the Valve Lift solenoid on Bank 1 was faulty, and so was replaced. Shop doesn't want to test with pulls over 5k (for I guess obvious reasons), so want to help point them in the right direction.
Same basic sequence to what let to the CEL last time happened again, and taking car back to dealer this afternoon. Obviously hoping we get it right this time, but hard to incrementally test/diagnose those conditions.
I'll admit to not being mechanically literate, but my thoughts was a wastegate getting stuck open or at least not sealing properly, just given the sequence and RPM ranges preceding the CEL.
I don't hear anything mechanical or notice anything different after I get the CEL, but I also reduce driving to under 3500 rpm. The CEL comes on a few secs "full off" throttle after "full on" throttle. Tech this afternoon confirmed it threw the same code. He's confused, as he thinks diagnosis was correct, so 2x checking the replacement solenoid installation.
I got a flashing CEL on a 996 GT2 and car shuddered on a hard pull and ended up being a coilpack had cracked. CEL went on when it happened and flashed a few times and then went off. Car ran fine with lower rpms, I drove it home and I didn't drive it after that until I replaced the packs but am guessing had I driven it and hit it hard again, CEL would have come on.
Interesting, I did replace the coil pack earlier this year right before I started getting the CEL as the were showing signs of deterioriation. Perhaps one was bad. I wouldn't have thought my sequence of driving behavior would have been coil related, but your indicating higher revs triggered it, so perhaps. Thanks, will have them check.
Looking for possible ideas on what could be cause:
Car drivers normal until Revs reach 5k RPM (so thinking 2nd turbo related) under hard pull (close to WOT) lasting only a few seconds.
Just checking you're not confused as to the rurbo operation as the above reads as if you think the twin turbo set up is sequential a la 959 when in fact it is parallel with both blowers doing equal work.
Just checking you're not confused as to the rurbo operation as the above reads as if you think the twin turbo set up is sequential a la 959 when in fact it is parallel with both blowers doing equal work.
Embarrassingly confirming I was thinking sequential boost on my car, as I had it in my head there must be something about getting on/off throttle higher in the rev range.
...... but my thoughts was a wastegate getting stuck open or at least not sealing properly, just given the sequence and RPM ranges preceding the CEL...
Our cars have blow off valves that are known to get stuck. More often actually with the fancy aluminum aftermarket ones vs the stock plastic ones. Also a famous thing to watch out for that could make you think you have a wastgate issue is if the VTG control arm on either turbo gets frozen or bound up. There was an advisory published to make sure to keep them lubed and confirm they operate smoothly by manual testing. But this is just speculation. What was the code accompanying the CEL?
To me the fault seems more turbo related from the symptoms. VTGs do not have waste gates. So a sticky actuator or the VTG itself may be faulty. To lube up the actuators is a $20 job so your shop swapping solenoids etc over kill until the more simple fixes ruled out. Remember your turbos are almost 15 years old and they do not like lack of use. These cars work best when used.
Hey all, sorry for delay. Here is a screenshot of the fault.
Spoke to tech this morning and his next thought was to pull out valves and test by blowing air and seeing if the high and low settings cycle correctly or if one gets stuck.
Wanted to solicit group think here first before digging into valves.
I suggested the VTG actuator and he is going to lube that, but not sure if that would result in the error code shown.
......I suggested the VTG actuator and he is going to lube that, but not sure if that would result in the error code shown.
I believe the code you posted can indeed be caused by a stuck actuator valve. Before he does anything else have him do this then clear the codes and test drive.
EDIT: also per another thread I found you should reset your ECU (adaptations) battery pull for +10 minutes before testing.
I believe the code you posted can indeed be caused by a stuck actuator valve. Before he does anything else have him do this then clear the codes and test drive.
EDIT: also per another thread I found you should reset your ECU (adaptations) battery pull for +10 minutes before testing.
I believe the code you posted can indeed be caused by a stuck actuator valve. Before he does anything else have him do this then clear the codes and test drive.
Thanks! This appears to have done the trick. He followed the service advisory (so did the original owner per service records, but over 12 years ago) so he lubed the actuator. I finally got time today to really drive the car hard. Lots of WOT pulls in 2-4th followed by completely coming off the throttle...no CEL.
09-25-2023, 04:09 PM
997.1 GT2 - Check Engine Light
