so i have a vq swapped sentra. My car recently started to misfire. I changed the spark plugs out and it was still misfiring. I was only able to test the 3 coil packs and the 3rd on the rear head. When i pulled the coil pack off cyl 1, i noticed a change in the idle. so then i tried the 2nd cyl and no change on the idle. 3rd changed the idle when i pulled it then i tried the 3rd on the rear head and it changed idle. so i figured theres an issue w/ cylinder 2. its not combusting. the coil pack is working because i tried swapping it out w/ cyl 1 and cyl 3 coil pack. idk what the issue could be.

any help would be grateful.

thanks in advance.

 

codes ? cel?

 

no cel after the new plugs were installed, sorry i don't have a reader. I do have a oil leak, my valve stem seals are old and have shrunk. plus my seals around a couple of the spark plug tubes are leaking. besides the oil leak or burning oil, i stay on top of my oil level.

 

so you had a cel light on and you installed the plugs and then reset the cel light and its off now(cel)? I would go to autozone and read codes or go to your mech to check em to find out which coil is bad.

 

not sure how to reset the cel, sorry im still learning about this stuff, but i did have a cel blinking light when it started to misfire, then when i installed the new plugs. no more cel.

is there any reason why a cylinder isn't combusting?

i'll try to get my friend to bring his scanner.

thanks again

 

is it constantly misfiring or just sometimes

 

constantly. this weekend i'll take the IM off and try to switch the coil packs with the rear head and have my friend scan it.

 

Rear coils are different than fronts

 

but yea its constant. you can hear the difference.

the coil packs are different? can't just swap them w/ the fronts? what would happen, just asking?

 

It could be the connector(s) bent in one of the coil packs, at least that was what happened to mine after i replaced my spark plugs the engine misfired all the time until I unbent the one of the connectors.

 

i'll look into that but i never tried unplugging any of my coil packs before. after the misfire, then changed the plugs, thats when i tried to move the front coil packs to see if its a coil pack.

thanks again for the help and for future help.

 

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VQ35 has all coils the same

 

yep, let us know if you fixed it.

 

so i can swap the coils with the rears then? since it was stated it wasn't the same by another user.

please clarify?

im going to test out the injector for that cylinder, see if i hear any ticking noise when its idling.

i hope theres nothing wrong w/ the block or have a compression issue.

thanks again

 

He meant the VQ30 that has differently designed right/left banks coils, but you said VQ35?

 

sorry yes, its a vq35, sorry i didn't specify which vq since this time frame had the 3.0 and 3.5.

 

up to what year injectors can i use? or are all 3.5's use the same injectors?

 

also, i did check to see if the fuel injector was clicking, which it was clicking or a ticking.

 

will be doing a compression test this weekend.

any other reasons why it might be misfiring?

 

so once i had more time, i took off the Upper IM and put the front 3 coil packs on the back head and the 3 coil packs from the back to the front head. Still misfiring.

I haven't done a compression test yet, i do have the tester and the spark plug socket but no extension or ratchet wrench to use.

I was wondering if anyone can provide more help or insight on what could be the problem?

thanks chris

 

If you changed the coil pack and it made no difference, I'd lean towards plugged injector. It would still "click", just not let any fuel through.
Diconnect the coil and run the engine for a minute or so. Then pull the plug. If it's dry, I think you'll have your answer.
(Even with low compression, that cylinder should still fire.)

 

checked the compression and theres no compression on that cylinder..... FML

 

what do i need to do from here?