Missfire on heavy acceleration
05 August 2005, 09:04 AM
#1
Missfire on heavy acceleration
Have a really weird misfire issue. Car runs fine in normal conditions If I accelerate hard in any gear it missfires then off she goes no problems.
Car has loads of mods and running circa 400bhp. Will look at the obvious like plugs and leads at the weekend but cant understand why it only occurs every now and again.
Any ideas ?
Car has loads of mods and running circa 400bhp. Will look at the obvious like plugs and leads at the weekend but cant understand why it only occurs every now and again.
Any ideas ?
05 August 2005, 12:25 PM
#4
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My car started doing this over the last 3 months (MY99), started intermittent and gradually got worse to occuring every outing but only under high load, and worse on higher boost. Then I had a severe misfire at 5000rpm at 1.55bar that saw a knock count of 60 with a boost spike to 1.76bar (nothing like dumping a large volume of unburnt fuel and air into the headers to make the turbo work a bit harder 
)
At this point I'd already changed my FPR cos I initially thought it was a lean stumble, without improvement.
So out came the spark plugs (PFR7B) which had only been in 5 months c8000miles, to find the gaps had increased to around 1mm and looking a bit tired. A new set gapped to 0.6mm and problem cured
Simon
)At this point I'd already changed my FPR cos I initially thought it was a lean stumble, without improvement.
So out came the spark plugs (PFR7B) which had only been in 5 months c8000miles, to find the gaps had increased to around 1mm and looking a bit tired. A new set gapped to 0.6mm and problem cured
Simon
30 August 2005, 06:23 PM
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Originally Posted by SiHethers
My car started doing this over the last 3 months (MY99), started intermittent and gradually got worse to occuring every outing but only under high load, and worse on higher boost. Then I had a severe misfire at 5000rpm at 1.55bar that saw a knock count of 60 with a boost spike to 1.76bar (nothing like dumping a large volume of unburnt fuel and air into the headers to make the turbo work a bit harder )
At this point I'd already changed my FPR cos I initially thought it was a lean stumble, without improvement.
So out came the <a style='text-decoration: none; border-bottom: 3px double;' href="http://www.serverlogic3.com/lm/rtl3.asp?si=24&k=spark%20plugs" onmouseover="window.status='spark plugs'; return true;" onmouseout="window.status=''; return true;">spark plugs</a> (PFR7B) which had only been in 5 months c8000miles, to find the gaps had increased to around 1mm and looking a bit tired. A new set gapped to 0.6mm and problem cured
Simon
)At this point I'd already changed my FPR cos I initially thought it was a lean stumble, without improvement.
So out came the <a style='text-decoration: none; border-bottom: 3px double;' href="http://www.serverlogic3.com/lm/rtl3.asp?si=24&k=spark%20plugs" onmouseover="window.status='spark plugs'; return true;" onmouseout="window.status=''; return true;">spark plugs</a> (PFR7B) which had only been in 5 months c8000miles, to find the gaps had increased to around 1mm and looking a bit tired. A new set gapped to 0.6mm and problem cured
Simon
I have exactly same problem now as you did runing at upto 1.25 bar no misfire after that increasing boost upto 1.5bar= missfire only thing is ive only had my new pfr7bs for 2months probly only done around 500-1000miles but they were set at 0.7gap for a while then reduced to 0.6 recently
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