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Right i have had a slight misfire on my R for a little while now, only really noticed it on part throttle holding it at say 2k rpm etc.
It wasn't really bad and always cleared at WOT so didn't worry too much no hesitation under load & drove fine bar a little hick-up at low revs.
It just used to burp & sound like unburnt fuel igniting.
Thought it was about time i looked into it so started renewing parts to see if i could solve it.
Changed my plugs to a set of NGK BCR8's and it made no difference (from BCR7es)
Then one night after getting a little bit too enthusiastic playing with an m3 i started to get bad hesitation problems, my car was fine at the time but not long afterwards it seemed to be holding back and the little miss had became a whole lot more apparent so nursed the car home to look further.
I did a compression test fearing the worst i got: 150psi, 153psi, 151psi, 150psi which i have been told is a good reading is this correct?
Also looked at tops of the pistons which are standard & couldn't see any pitting etc.
Checked plugs which have no damage, re gapped them to 0.8 as they where a bit out but this didn't cure the problem.
Since then i have changed the Dizzy cap & rotor arm driving it after both but it still hesitates.
I have done a fault code check and it pulls up all clear with a 55 every time.
Tried moving the dizzy which made no difference so put it back to the original markings as i thought maybe it had moved.
Also me & a friend shimmed the head as it through a rocker arm last year and the valve clearances were miles out, quietened the head but made no difference to my fault.
Cant seem to see any boost leaks, checked the turbo for shaft play & it seems ok, also pulled the pipe of the waste gate to see if it was sticking & it boosted all the way up to 1.3 bar then i let off.
Cant see any petrol leaks around the injectors, ran cotton buds around them as i thought this would pick up if the o-rings are leaking or is this not a good method?
Took off H.T leads & inspected them & sprayed with contact cleaner as i could see not visible damage or hear them arcing.
The car is the usual 1 bar mong spec, so has a front mount, walbro, mongoose etc.
It is always run on 99 octane or if not its 97 so doubt its crappy fuel.
Had the same sort of symptoms before but with less of a misfire but it threw code 34 so changed the det sensor which solved it last year.
As a side note the problem seems more apparent when the car gets up to full running temp, never noticed it before as i don't drive the car hard until its warm but to test it i did the other night and the miss on part throttle was still there but it didn't seem to hesitate anywhere near as bad & pulled a lot harder.
Symptoms are: Hesitation through the rev range at WOT, almost seems to surge on & off power,
Generally a lot slower/less power & seems to take longer to build boost,
Misfire when held at part throttle,
Exhaust note seems to have changed (deeper mismatched tone)
Hesitation seems worse when the car is warm
Any input would be great as this is driving me mad & i need to get it sorted asap as i am booked up to go to the ring in it next month so im getting a bit worried! :-O
It wasn't really bad and always cleared at WOT so didn't worry too much no hesitation under load & drove fine bar a little hick-up at low revs.
It just used to burp & sound like unburnt fuel igniting.
Thought it was about time i looked into it so started renewing parts to see if i could solve it.
Changed my plugs to a set of NGK BCR8's and it made no difference (from BCR7es)
Then one night after getting a little bit too enthusiastic playing with an m3 i started to get bad hesitation problems, my car was fine at the time but not long afterwards it seemed to be holding back and the little miss had became a whole lot more apparent so nursed the car home to look further.
I did a compression test fearing the worst i got: 150psi, 153psi, 151psi, 150psi which i have been told is a good reading is this correct?
Also looked at tops of the pistons which are standard & couldn't see any pitting etc.
Checked plugs which have no damage, re gapped them to 0.8 as they where a bit out but this didn't cure the problem.
Since then i have changed the Dizzy cap & rotor arm driving it after both but it still hesitates.
I have done a fault code check and it pulls up all clear with a 55 every time.
Tried moving the dizzy which made no difference so put it back to the original markings as i thought maybe it had moved.
Also me & a friend shimmed the head as it through a rocker arm last year and the valve clearances were miles out, quietened the head but made no difference to my fault.
Cant seem to see any boost leaks, checked the turbo for shaft play & it seems ok, also pulled the pipe of the waste gate to see if it was sticking & it boosted all the way up to 1.3 bar then i let off.
Cant see any petrol leaks around the injectors, ran cotton buds around them as i thought this would pick up if the o-rings are leaking or is this not a good method?
Took off H.T leads & inspected them & sprayed with contact cleaner as i could see not visible damage or hear them arcing.
The car is the usual 1 bar mong spec, so has a front mount, walbro, mongoose etc.
It is always run on 99 octane or if not its 97 so doubt its crappy fuel.
Had the same sort of symptoms before but with less of a misfire but it threw code 34 so changed the det sensor which solved it last year.
As a side note the problem seems more apparent when the car gets up to full running temp, never noticed it before as i don't drive the car hard until its warm but to test it i did the other night and the miss on part throttle was still there but it didn't seem to hesitate anywhere near as bad & pulled a lot harder.
Symptoms are: Hesitation through the rev range at WOT, almost seems to surge on & off power,
Generally a lot slower/less power & seems to take longer to build boost,
Misfire when held at part throttle,
Exhaust note seems to have changed (deeper mismatched tone)
Hesitation seems worse when the car is warm
Any input would be great as this is driving me mad & i need to get it sorted asap as i am booked up to go to the ring in it next month so im getting a bit worried! :-O
hopefully your get it sorted fella .
