Still having Rain induced misfiring

[HarryPotter]

I did the stupid thing and just started replacing parts, new cap, rotor, bav auto sport wires and I am still getting just the weirdest misfiring ever.

It's been raining like a whore here in a Florida and after a rain or during the car just runs very, very poorly. I thought it was temp related but I am not so sure. The car will misfire and have almost no power until about a 5 minutes of driving. Seems to happen even if the car is up to temp. Then like fucking magic it just disappears and runs completely fine. If it hasn't rained then everythings fine car runs great like it should.

Even after a very muggy night I will get misfiring on the first start up in the morning. Car will idle fine but get on the power while in gear and it just will not run.

Crank sensor? I thought so but wouldn't it run bad all the time if this was bad? Maybe coolant temp sensor? Dumping in way too much fuel until the car is fully warm? I have no idea at this point and it's really starting to get annoying. Any help or ideas at all would be greatly appreciated. About to start tearing my hair out here.

I've done a ton of work lately and this little problem is still persisting. Replaced the diff bushing, new shocks, new radiator, cap, rotor, wires, plugs.

Is there any chance a shitty battery could be causing this? I know it sounds crazy but I've heard of stuff like that happening before. My battery is really crappy and in dire need of replacement. Again any help would be greatly appreciated. I am just out of ideas and don't want to keep throwing money at it in hopes of replacing the bad part.

I only gapped one plug but FFs that shouldn't be the culprit either since it would run shitty all the time no? It was late and I am lazy.

[HarryPotter]

Cleaned out the ICV, and sprayed some electrical cleaner on that plug for the fuel injectors. I dunno really. Can't really test it out until it rains. Which should be soon lol.

Spraying stuff down with a water bottle effects nothing.

[jlevie]

If this is an M20B25 engine, the CPS is a possibility. Perhaps moisture is getting into the CPS, connector or Wiring and degrading the signal until everything heats up enough to drive out the moisture. The same could apply to the engine wiring harness as the CPS signals reach the DME via small coax wires in the harness.

I have run into other random problems (though not rain related) that ultimately were fixed with a new OE CPS and new OE engine harness. You could try a used harness, but that is something of a crap shoot. I have four supposedly good used harnesses that I've never bothered to throw out that all had CPS or other faults. In each case the pricey (~$700) BMW harness was the ultimate solution.

Other than that, I don't have a clue as to what might be going on.

[wilholl]

2 areas where I have had problems with water causing mis-fire and stalling
have been:

1) check the O2 (oxygen) sensor connector, directly under the front engine compartment battery tray for water inside the connector.

2) water can run down the injector harness and get inside the connector shell. Carefully peel back the rubber cover and check for water there.
I say "be careful" because I broke a wire off of one of the connector pins once. That is not fun to fix at all!!

[///M42 sport]

318? I've Had same problem solved by replacing coil pack

[HarryPotter]

It's a m20b25, 87 325i.

God I hope it's not the harness. That'd be catastrophic. Think this all started happening one day after I washed down the engine bay with a fucking hose. I am really thinking it's the CPS or that fuel rail connector under the intake. I'll take a good look at both tomorrow. The rain has let up as of a few days ago so it hasn't been bad at all. I'll carefully check that connector under the intake tomorrow first. It just sucks as I need it to rain or be muggy as hell to see if anything is actually working.

Thanks for the replies.

Also, my old dizzy cap seemed to collect a lot of moisture inside for some reason I haven't checked the newish one yet. But the one time I pulled off my old cap there was literally droplets of water inside of it. No idea what could have been causing that.