L98 engine misses/plays up at WOT

[Justinaxe]

Gday all ...
So far I reckon I have shaved 10 yrs off my life trying to troublehoot this problem with my '06 SSV.

Basically at WOT and heavy acceleration (about 60% TPS) and over 3000 RPM the engine developes a fairly rough miss, or at least to sounds like a miss especially with the extra vibration and poor performance.. When you go back to idle it will go back to normal after a minute or so or if you swtich off and restart the car.

Thus far I have replaced plugs (and gapped them correctly) , meter tested the coils and leads and all have the same resistance as the other.
I have also had the vehicle on the computer (hptuners) for misfire codes or any other tell tail signs with no result (or nothing that stands out anyway).
All the old plugs were in good condition except on bank 1 where there was an exhaust leak which was fixed as well..
The engine is very fresh as it was a ground up rebuild around 10k kms ago and hasnt missed a beat until the other day .

The car drives perfectly well under normal conditions but with any heavy acceleration it developes the above problem ..

Any suggestions and help would be appreciated as the next door neighbours and family are getting sick of learning new ways to incorporate "you f^#king c*&T of a thing" in every sentence.


Cheers

Justin

 

[07GTS]

does anything look odd on the hptuners scanner when its playing up..? should be able find out whats going on looking thru the data

 

[Justinaxe]

One thing that didnt make sense apart from the STFT with the exhaust leak was the MAP reading fluttered around 89 after the clutch was engaged straight after the "miss"/problem kicks in (effevtively idle but obviously still braking to a stop) the car was tuned in SD (so mafless) which is the only thing that I would class as odd ..

 

[Justinaxe]

I wish I could post a screen shot on here but my lack of computer skills limits me at the moment
I should say that the fact that the MAP reading with clutch in (mafless tune) seems odd

 

[07GTS]

yea would good to see the log, does the timing or fuel do anything different, how do the o2's look..?

 

[Justinaxe]

Ill see if I can get a log file on here today or at least a screen shot . The O2's are bouncing around within range (not flatlining) , fuel status switches to Laccel/deccel(which im guessing is PE mode) from Closed loop , Im not getting any Knock retard apart from .8dg between shifting (which is fine). Thanks for your help as well mate and Ill get that log up here shortly