P1 'kangaroos' under slow acceleration after track day -WHY?
Discussion
After a lot of laps at a wet day round Brands Hatch on Monday, at the end of the day when flooring 3rd gear and lifting off, the car was more jerky than normal a couple of times.
On the 3rd time of doing this on the same downhill bend, then accelerating out of the corner on the straight 3rd and then 4th gear were very jerky/kangaroo but after slowing down and returning to pits everything seemed ok.
Now, when accelerating very gently at low revs the car does not feel 100% smooth alebit not a real problem either. Press the throttle harder then the turbo kicks in, everything is fine.
Strange as it seems maybe something is in the fuel or the fuel pump is weak at low revs, not sure. ANY IDEAS?
Cheers
Lawrence
On the 3rd time of doing this on the same downhill bend, then accelerating out of the corner on the straight 3rd and then 4th gear were very jerky/kangaroo but after slowing down and returning to pits everything seemed ok.
Now, when accelerating very gently at low revs the car does not feel 100% smooth alebit not a real problem either. Press the throttle harder then the turbo kicks in, everything is fine.
Strange as it seems maybe something is in the fuel or the fuel pump is weak at low revs, not sure. ANY IDEAS?
Cheers
Lawrence
Could be a boost leak, fuelling, faulty MAF or O2 sensor...anything!! Without looking at it up close and personal this one is difficult to diagnose remotely so anything anyone tells you on here is just a guess.
Generally speaking though rough running like that low down the rev range and when the engine is up to operating temp and running in closed loop mode, and then on boost and running primary open fuel map values (open loop mode) everything is good would lead me to guess an O2 sensor is going or has gone down. Further up the range it could be MAF sensor. Again, difficult to say.
Go see a Subaru specialist and get them to check for any Error codes in the ECU (DTC's). You don't always get a check engine light when a sensor is malfunctioning so it might not be apparent that there is a sensor problem.
Generally speaking though rough running like that low down the rev range and when the engine is up to operating temp and running in closed loop mode, and then on boost and running primary open fuel map values (open loop mode) everything is good would lead me to guess an O2 sensor is going or has gone down. Further up the range it could be MAF sensor. Again, difficult to say.
Go see a Subaru specialist and get them to check for any Error codes in the ECU (DTC's). You don't always get a check engine light when a sensor is malfunctioning so it might not be apparent that there is a sensor problem.
Scoobie, you're a star. You have answered many of my questions on here before.
The vibration through the car issue which must have been wheel/tyre related as straightning a bent wheel combined with giving the tryes some stick seems to have solved it!
I think it needs a service anyway so hopefully that should sort things out.
Cheers
The vibration through the car issue which must have been wheel/tyre related as straightning a bent wheel combined with giving the tryes some stick seems to have solved it!
I think it needs a service anyway so hopefully that should sort things out.
Cheers
Vixpy1 said:
2 questions
1) Was the fuel level getting low
and
2) Have you got an induction kit fitted?
1) Yes and i filled up about 5 litres from the most friendly Evo boys we shared a garage with who sold me some spare fuel from a jerry can!1) Was the fuel level getting low
and
2) Have you got an induction kit fitted?
2) definitely not - no need to touch what is already a perfect car!!
Evos suffer from this part throttle jerkiness and I believe it's often caused by "reversion through the MAF" - which I don't really understand, but gather that it's to do with air being forced backwards through the MAF during part throttle situations causing the ECU to throw a wobbly with the ignition/fueling as it can't read the airflow properly.
The cure on the Evos is to fit a new dump valve or clean the existing one. I've done this on mine and it significantly reduced the problem almost to the point of a total cure.
The issue has now resurfaced (about 5,000 miles after cleaning) and I'll give the dv another clean and see if it helps again.
I believe the dv gets dirty because the rocker cover breathers are routed into the induction, meaning that oil vapour gets sent through the induction, gunking up the dvs which then do not open and close smoothly, causing the reversion.
The problem is supposed to be permanently curable by fitting a baffled oil catch tank in the breather circuits, but I haven't got around to doing this yet.
The cure on the Evos is to fit a new dump valve or clean the existing one. I've done this on mine and it significantly reduced the problem almost to the point of a total cure.
The issue has now resurfaced (about 5,000 miles after cleaning) and I'll give the dv another clean and see if it helps again.
I believe the dv gets dirty because the rocker cover breathers are routed into the induction, meaning that oil vapour gets sent through the induction, gunking up the dvs which then do not open and close smoothly, causing the reversion.
The problem is supposed to be permanently curable by fitting a baffled oil catch tank in the breather circuits, but I haven't got around to doing this yet.
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