EJ22 misfires and I don't know why (solved)

[valkura]

Ok. It's an ej22. Plugs were replaced (NGK V-Power); wires, coil, ignitor, coolant temp sensor, o2 sensor, knock sensor, and maf are tested or replaced and all seem to work fine. Injectors don't seem to be the issue either, nor fpr. I've gotten misfire codes for all cylinders, but lately only 2 and 3 are coding (I'm assuming they are just the lucky winners lately). Done compression and leakdown tests, it's solid.

Driving, it runs fine when cold, then seems to gradually get worse. It seems to react to both throttle and rpms. It starts to develop issues somewhere in the 3k-4k range, but outside that runs ok, then as it gets warmer it pretty much misfires from 3.5k up. It also gets more throttle-dependant as it warms up - it becomes a challenge finding that one happy spot where it doesn't misfire, lol.

It uses a buttload of gas too. Like... 14mpg.

The only codes it has ever given me are misfires. I've gone through enough of it now that I'm wondering if I have an ecu or grounding issue or something :\

It'd be great to have it running right, since I deliver pizzas now, lol. Any ideas?

[hallowpoint]

fuel pump maybe

[valkura]

Seems pretty unlikely since it doesn't have the issues when it's cold. I'd think it'd have issues with acceleration/anything requiring more fuel all the time, not just when it's warmed up :\

[Huffer]

Have you tried the Throttle Position Sensor, or even the crank sensor?

Honestly it does sound a lot like a vacuum leak - typically when an engine warms up it moves out of closed loop and relies on vacuum sensors for inputs - hoses warm up and they expand, and this makes any leaking/cracked/busted hose a much bigger issue.

[valkura]

I've unplugged the tps and found it didn't make the misfires go away (from what I've heard cars will run ok without them, so if it's shooting out bad numbers unplugging it should make it just run off the maf?)

Crank sensor I haven't checked, wouldn't that make ignition timing all whacky? From what I can tell mine is fine.

I'll potentially look into a vacuum leak issue more, you have a point with the expanding hoses.

[d1giPhux]

same thing happened to me.. would start off working okay, and then as mine warmed up would misfire. Turned out that the timing belt had jumped a couple degrees or something and had to be re-done. After doing that.. was all good again. Maybe something to consider.

[02_Legacy]

Crank sensor I haven't checked, wouldn't that make ignition timing all whacky? From what I can tell mine is fine.


I had this sensor go bad in my sisters maxima, and it would kinda do the same thing, once it warmed up it would just shut down. I figured it was because the oil got on it or something like that because when I took it out and wiped it off it started again, otherwise it wouldn't start for a while, but it does make sence, if it is going bad maybe it can't "keep up" as your engine revs sending bad timing to the injectors and plugs. Just my thoughts

[1996Battlewagon]

Like d1giPhux said, you might want to check your timing. Also, do not rule out your fuel pump. Fuel pump problems usually get worse when the temp rises.

[valkura]

Yeah, I'm gonna check the timing as soon as I have time :\ What causes fuel pump problems to get worse at higher temp? (I've been using this breakage as an opportunity to learn about how the thing works, might as well continue that trend, heh)

[valkura]

same thing happened to me.. would start off working okay, and then as mine warmed up would misfire. Turned out that the timing belt had jumped a couple degrees or something and had to be re-done. After doing that.. was all good again. Maybe something to consider.You win an internet. Timing belt had skipped a tooth, finished straightening it out today. Runs great now. \o/

[Grafton]

http://knowyourmeme.com/system/icons/1732/original/winternet.jpg

[DarkPhoenix]

Glad you got it fixed. That same issue was plaguing me for over a month. Turns out the previous owner reused the old tensioner and the belt jumped a tooth.

[d1giPhux]

Nice! Glad to see you got it fixed! Yeah.. same thing happened to my car, not sure why but I think mine was because the tensioner or one of the pulleys had got seized up and failed or something. Either way.. glad I was of some help!