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09-27-2017
Okay so I just got a new GTP the mods are 3.4 pulley, pacesetter headers, 3" inch zzp exhaust, wizaird intake system, zzp tuned. I have a aeroforce scanner and i'm getting a misfire on cylinder #4 at idle. Now it goes away if you turn on A/C or accelerate. My scan gauge does not read any misfires under accelerating. I'm wondering if anyone would know why i'm getting these misfire?
09-27-2017
Swap plugs around, see if it follows.
09-27-2017
Same with injectors.
Check vacuum lines and coil packs, too.
09-27-2017
Are you getting any codes or pending check engine lights?
09-28-2017
No I'm not getting any check engine lights. Coils are new along with plugs. They are autolite 104s. I got injectors from zzp just stock but they were tested good before I got them
09-28-2017
Also forgot to mention new 10.5mm plug wires from zzp. New idler pulley, water pump, crank sensor, new lim gaskets.
10-10-2017
what vacum lines should be checked
Originally Posted by blueguy91
10-10-2017
did this miss come after the plug change? if so you likely cracked the spark plug. swap it with the one next to it, see if the miss moves.
you might just see a black line in the plug too, then you know its cracked.
or you got a chipped piston.
10-11-2017
Air/Fuel/Spark...
with misfire, swap plug (check gap too), wire, coil pack, then injector. Do this to see if the misfire follows, if so, you've found your problem. If not, then compression test, problem could be heads (valve) or worse, as Scotty says, a piston with a hole in it.
I'm going to bet coil pack
10-11-2017
What should a compression test run with a motor that has 212 on it?
10-11-2017
how about some back story, why i asked the questions i asked.
10-11-2017
It might vary some but 150-165ish give you take some.
So long as one cylinder is way low compared to the others, like if all are at 160 but cylinder 2 was at like 130 then you may have an issue.
10-11-2017
Sorry scotty.. the car was my dad's he had it for 10 years. He meticulously took care of his vehicle(s). Each cylinder was reading 150 - 160.. also even after plug changes it's been doing it for the last year or so he hasn't figured it out.. it's a weird misfire..
10-11-2017
I had constant misfires on cylinder 4 for about a year until I started getting other cylinder misfires and it turned out to be a crank sensor.
10-12-2017
Could the problem also be the fuel pressure regulator??
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