coilpack going bad?

[drifter808]

Recently my car has been misfiring at idle.BTW its an SR. it holds idle fine but makes a sputtering noise at idle. It only does this when its cold but when its warmed up it will only do it a little. It is also kind of dead in the high rpms, like 6500 to redline. Could this be a coilpack going bad. i searched but didn't find anything with the same symptoms. Or maybe i just suck at searching but i looked at all the threads under bad coilpacks. I have not changed the fuel pump since the swap and the car had 200xxx miles on it and was probably never changed. im gonna try and put in a 300zx TT tomorow if i have time. maybe thats it.

If anyone has had these symptoms or know the culprit please help me out.

Derek

[tripleb]

well mis-fires can be alot of things one of the most common things it actually bad or mis gapped plugs. wires and coil packs can be the culprit to

best thing to do is start with the plugs and go from there. check to see if the plugs are bad then check to see how good the spark is by testing the wires. if the sparks weak you may have a bad wire or even a coil pack

[reactor]

To test the coilpack just unplug it and test the 2 left terminals on the coilpack for resistance. You should get approximately 1 ohm resistance. Another easy way to test the coilpacks is to get an inductive timing light and place it over the wiring to each individual coilpack. This will show you the misfires visually. Note: Not all inductive timing lights can pick up the signal from the coilpacks.

[drifter808]

Yeah my plugs are new but i didn't check the gap. there the NGK BKR7E and i think the gap is good on those already but i'll check. I'll try the inductive timing light tomorrow. thanks for the tips.

[oumu]

Originally Posted by drifter808

Yeah my plugs are new but i didn't check the gap. there the NGK BKR7E and i think the gap is good on those already but i'll check. I'll try the inductive timing light tomorrow. thanks for the tips.

I'm pretty sure the NGK BKR7E come with a gap of 1.1mm which is too big. It should be closer to 0.9mm or 0.8mm. That could definetly cause a misfire because the spark will "blow out"

[smithers584]

you could even unplug each coilpack as the car was running, your engine will bog down as you unplug one if its good, if you unplug one and the motor doesnt change at all, then that coilpack is bad.

[drifter808]

Thanks for the tips. I'll adjust the gap on the plugs and see if that helps any. I also played with my timing a little today and it helped out some. it was a little off but not much so now its at 15 degrees. Im gonna try unplug the coilpack when running and see what happens. Any ideas on why my top end is so dead?

[smithers584]

well if you are like me, its because you have the stock turbo. you could be running out of fuel if you are on the stock pump or if you have a bad coil pack that would explain it. we would need more info about the set up and tuning to tell cuz it could be a lot of things: plugs could be causing it, try gapping them at .28. When you pulled your old plugs did they show any signs of a lean condition or rich? have you tuned your car? what kind of boost controler are you using? do you have a boost gauge? have you paid attention to see if your boost is dropping off?

[drifter808]

When i pulled the plugs out they weren't showing any signs of lean or rich. they were in the sweet spot. Im running stock turbo. My car has not been tuned but will be within this month, i am using an HKS adjustable actuator now but will be upgrading to electronic sometime. Its set at .5 bar on my boost gauge. I have a walbro fuel pump. My boost isn't dropping off from what i can see it holds pretty steady at .5 bar. Maybe im getting to much back pressure cause its stock size piping just with no cat and a different muffler. Thanks for the help.