cylinder 2 and 5 misfire??? [Archive] - Forum


View Full Version : cylinder 2 and 5 misfire???

10-31-2005, 02:32 PM
OK, There is really somthing wrong with my engine. I have checked everything I can possibly think of and have come up with nothing. I have checked all my spark plugs and they are all sparking fine. I took apart my fuel injectors and found that 3 of them were a little dirty and just replaced them. I have checked the vacume on the cylinders and that is fine also. Any ideas, I have checked all the threads and there is nothing.

Thanks for your imput

10-31-2005, 04:48 PM
I had a head gasket that was going and leaking coolant into the combustion chamber. I also registered misfires. I hope that helps.

10-31-2005, 05:04 PM
check you coilpack it could be going bad

10-31-2005, 05:09 PM
all of the above. Maybe do a compesion check.

10-31-2005, 07:29 PM
get your fuel injectors cleaned at the dealer.

10-31-2005, 09:56 PM
2 and 5 is the first coilpack (going from left to right) .. I'm thinking coil pack too.

11-01-2005, 02:13 AM
I second the coilpack. Had one go bad on me and at first it caused a mild backfire twice. The next day it died....DEAD! MSD coilpacks are pretty inexpensive so why not replace stock with performance. But replace all 3 pack at the same time.

11-01-2005, 01:39 PM
well, I checked the coilpack already and they are fine, did a compression test and that came back normal, but when i did a vacume check, I only got about 5 lbs instead of 15? Whats up with that, it doesnt make sense at all. Also, the injectors are definately not to problem since the injectors in 2 and 5 are brand new and do work. I had my friend who owns his own shop take a fiberoptic camera and look down into the heads to see if there was any leaking into the cylinders from a bad gasket and we found none at all.

thanks for the imput though

11-02-2005, 06:38 PM
And you replaced the spark plug wires?

11-03-2005, 04:05 PM
yes, that was the first thing i did.

11-03-2005, 11:44 PM
did you try switching the coil packs? like from 4 & 1 to the 5 & 2 spot then put the original 5/2 coilpack on 4/1 spot to see if 4/1 misfire then? Then you'll know if its the coilpack or not.

Cuz checking coilpacks are tricky, theres a primary and secondary output. Then ya measure the 2 towers with the ohm meter thats the secondary side of the coil while the primery side might be bad or going.

11-04-2005, 11:23 AM
I posted a thread many months ago on cleaning the coil pack terminals. This solved a slight mis-fire I was experiencing.

Take a look and let us know if it helped.

11-04-2005, 02:20 PM
ya, actually, to check the coil pack i borrowed my friends. He has a 99 grand am aswell. So I just switched out mine for his and checked it real quick. No change!

11-04-2005, 11:30 PM
ya, actually, to check the coil pack i borrowed my friends. He has a 99 grand am aswell. So I just switched out mine for his and checked it real quick. No change!

How many miles are on the plug wires? Stock plug wires usually last around 60 - 80k miles before they start going to crap out. If they weren't changed yet, I'd bet its them. Even though they might spark fine when test it with a screwdriver to metal ground, Under a car load it might be different.

Other than that. I dunno what else might cause it to misfire. Hmm.. a dirty MAF sensor will do it. When a wire broke inside of my MAF unit plug harness (cuz my CAI didn't have enough slack for the MAF harness), My engine misfired from not having a reading from the MAF unit. That would my be 2nd guess.

11-06-2005, 05:47 AM
I had a similair situation with 2 cylinders on the same coil pack not firing. Swapped 2 packs and the problem stayed on the same 2 cylinders. Turned out the ignition module was bad (not triggering that coil pack) If you already proved the coil pack is good, then the ignition module is where I would look next (the piece the coilpacks bolt to).

11-07-2005, 02:24 PM
thanks, i'll try that.

11-17-2005, 03:40 PM
well, tried a new ignition module and the problem didn't get corrected. Any other ideas? I am at a loss.