Misfire Under Load - Hawkeye STI - Diagnostic Help Needed
 

Hi All,

Just been to Wales for the weekend to visit the parents. Weather was terrible, floaded roads everywhere, but car and I had a decent enough time as carefully as we could.

Driving there was fine, no issues at all.

Driving back the car developed quite a shocking splutter/misfire/hesitation under load - by load i mean heavy acceleration (80-100% throttle)

If am driving with light throttle building across the revs i don't feel anything quite as bad and the car pushes on very well - almost as well as driven "normally". However, if i am hard on the throttle the car comes onto boost and then at about 4200rpm the car bogs down. I can push/rev past this but it then hesitates all the way to say 6700 rpm.

Let off the throttle - 20/30% throttle - build power slowly through revs, no markable hesitation or misfire.

Back hard on throttle - 80-100% and it happens again, hits a big wall of nothing.

No CEL thrown. No data that looks odd through code reader/torque app. (I know not perfect).

Boost pressure looks ok.
Oil Pressure - roughly 5-6 bar under load and 1.7-2.0 Bar at idle. Depending on temperature.

Engine Mods -

Forged 2.5
Mahle Pistons
Cosworth Heads
Stock Air Box + Cosworth Panel Filter
Forge BOV
Full Decat Exhaust
VF35 Turbo
Andy Forrest Map
Only ran on Shell VPower (not ever Tesco) - tank of fuel put in yesterday after getting down to roughly 1/4 tank.

MAF was recently swtiched out for an oem bosch item about 4/5 months ago by myself. Dont think any issues there.

Could this be a symtom of a turbo failing? I have a vf35 currently (new turbo in the wings already) and i wondered if the symptoms of a bad turbo / seal may be the culprit? Reason i think turbo is that i think the seals are going - lets a bit of oil through and i get a bit of smoke on startup sometimes (very very rare like 2/3% of all my startups and only over last 2 months).

Only other noticeable possible factor - water - the roads were covered and flooded and she is a low car and had to wade through numerous puddles - but none of that could have got anywhere near the engine or caused damage i'd have thought, low or not?!

Other culprits ?

Really tough and i'm worried as its a 2.5 that maybe its a bigger issue - but feels like its timing/spark/fuel related.

perhaps coil pack related

I got home, was doing the same thing under load pretty much last quarter of the journey.

Pulled up and had her sit for an hour at home before having to go drop my kids off and she ran fine - let her up to temp and gave her a blast and no hesitation and no misfire under load, clean and accelerated hard all way through to redline.

So definitely an intermittant fault. Can only think its because the car had time to cool - would heat effect the coil packs/plugs in that kind of way?