Misfire that I can't quite seem to figure out

[bkaesvziank]

So to give a little backstory, a few years ago, my car started to miss and then that turned into it running crazy rich, would barely run and couldn't figure out why. It ended up being the DME. So once I found that out, I replaced the DME, chip, and injectors. Awesome, car ran great for awhile. I've been having a misfire for the last year now that I can't quite seem to track down. It's not constant, and it's usually cruising speeds. Lately, it's been getting worse and it's under load, at cruise, and at idle. On cold starts, it usually runs well for a few minutes and then starts to miss again. So this morning, I unplugged the O2 to see if that would do anything. It has made a definite improvement. Not exactly perfect, but much better.

This kind of seems like what happened a couple years ago but definitely not as quick. Is my car just eating computers for some reason? I feel like there has to be some other possibilities. I have plugs/wires/cap/rotor ordered so we'll see if that makes any changes but I was wondering if you guys had any ideas.

[Rookie88]

Can't really offer any help, but might be going through the same thing as your prior issue on my 2.7i build and hoped I could add on. We scoped the coil when we were diagnosing and noticed it fires off with seemingly every tooth on the crank and definitely smells really rich. Did you ever notice anything with the coil control side of things?

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[bkaesvziank]

I'm not sure. All the parts should be in tomorrow so I can let you know then.

But my car is back to running like shit. But I've noticed that it's strictly under load. If I baby the car up to freeway speeds and keep it at a low load, the car runs perfectly fine. But the moment that I start to put any load on the car, it starts to miss like crazy again.

I pulled the plugs and they looked slightly lean albeit still okay. I'm starting to think it may be fuel related now. I'm going to check the fuel filter and see if that looks like it needs to be replaced.

[nrubenstein]

Get a fuel pressure tester.

[bkaesvziank]

I replaced the fuel filter, plugs & wires, coil, and cap and rotor. The rotor looked pretty torched and I'm pretty sure that was the culprit. I replaced the coil before everything else and it helped a bit but didn't totally resolve the issue.

[325e '87]

The DME uses coolant temp and the oxygen sensor for adjusting the fuel injection. If you are having issues that reveal themselves when the engine is hot it could be just these sensors.

[bkaesvziank]

Ok so I replaced everything in my post above and the problem went away for a few weeks. But now it's back to the same way it was. I also checked fuel pressure which tested fine. The odd thing about this miss is that it even misses when the throttle is completely closed and I'm just coasting. I ended up replacing the main relay and that didn't fix anything. I'm not sure what else there is that I can check.

[MrBurgundy]

Sounds like an ignition problem.

Check your CPS