i have a 99 gtp getting a misfire under load and/or into boost... only #1 idle is fine seems to have good comperssion changed all plugs 104s wires acdelco swapped pcm, icm, coils, injector any ideas?
thanks
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11-03-2012
i have a 99 gtp getting a misfire under load and/or into boost... only #1 idle is fine seems to have good comperssion changed all plugs 104s wires acdelco swapped pcm, icm, coils, injector any ideas?
thanks
11-03-2012
So no matter what you switch (plug, injector, coil) this miss remains in CYL #1? Is everything else operating normally? Coolant remains full, oil is good?
11-03-2012
yes everything appears to be good......no overheating or milkshake.... does this sound like a chipped piston? my thought was the compression would show that? exhaust doesnt appear to be obstructed... the thing that i dont understand is i was able to get a p0300 cleared and havent gotten that again...
11-03-2012
do a compression test
11-03-2012
You running at least 91 octane?
11-04-2012
Had this exact same problem, For me it was a vacuum leak. Check all your vacuum lines (literally take off the couplers) and check them for cracks... a spray test didn't show any issues with mine but when I pulled the vacuum line to the throttle body, it was split on the bottom.
11-04-2012
93 octane, vac at map senser is normal and boost gauge read the same but will double check all vac lines for leaks
Thanks
11-10-2012
ok ive had no luck with anything replaced vac lines with "t"s lower intake manifold gaskets... still no change will throw a p0300 has 120 psi compression..... scratching my head?
any other advice?
thanks
11-10-2012
What are your other cylinders compression? You can't just check one and call it good.
11-10-2012
well i understand that but why would my aeroforce show a misfire in cylinder #1 and the compression in another cylinder cause it to misfire there? the p0300 code is a random misfire and only misses on the #1 i checked #3 it was 125 with both plugs out...
11-10-2012
Check the compression in all 6 cylinders and report the #'s and compare them to verify I believe if they're are within around 10 or less difference between them. Just checking one cylinder your going to have a hard time finding a number to compare it with.
11-17-2012
mods to warrant 104's??? spark might not be hot enough to fire that cylinder if there arent any substantial modifications increasing cylinder temps, and if possibly and i mean its a stretch but maybe compression on cyl1 is just low enough coupled with the lowered heat of the 104's causing cyl1 to miss, but im gonna stick with the first and get some autolite copper 605's... also nasty vacuum leaks can occur between sc and lim and sometimes even changing the sc gasket wont neccessarily fix the problem... what i did was place some GRAY rtv on both sides of the sc gasket around the intake port and that fixed it... best way to fix tht one is to have the intake manifold resurfaced tho... just some suggestions good luck
12-02-2012
sorry it been a while since i have updated... got this thing figured out it was a combination of things...bad supercharger gasket and a bad new spark plug...
thanks for the help!
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