1991 325i m20 help, madison

cpandrewschmidt

Update - Ran a homemade smoke test with a compressor and paint can trick. Worked like charm. One very small vaccuum leak on the bottom of the hose that attaches to the valve cover. Took it off and it basically snapped apart it was so brittle. Ordered a new one.

While waiting for that to come in I popped the valve cover and adjusted the valves. There wasn't 1 that I could get the feeler under, so they were pretty tight. I adjusted those to the best of my ability. Definitely a finky job. I don't feel like I did as good as I could have, anyway...

Hose came in today and put it back on over lunch. Fired it up. Seemed to still do the same thing initially but settled down after a little bit. DME adjusting itself?? I let it idle for 5 mins before working up the courage to take it out. Drove it for 10 mins around the subdivision and a road up to 45 mph. Knock on wood it performed well. Going to put it through some more rigorous driving tonight.

I did notice my idle dropped to the 800 ish rpm range, where before it was about 1100 rpm. So, I think that's a good thing too. Valves still seem to tick a bit, there's probably one or two that aren't quite right.

Doorman

Good deal brotha!!!

If you could, share your homemade smoke machine pictures please?

jc43089

I am not sure if the version of Motronic you have adapts like the ECU in the e36 but you should reset it by disconnecting the battery and touching the cables together to clear the ECU and force it to relearn the engine. On the e36 you have to do this anytime you make a modification and/or fix a problem like that. I installed a lightweight flywheel in a 328 and it would hardly idle until the ecu was reset, then it relearned and smoothed right out.

cpandrewschmidt

Drove it more last night. Still has some sputtering issues, but not NEARLY as bad. I at least feel like I can drive it to places. It smooths out more after its warmed up. Still might have to take up a couple of your offers to look things over to see if I'm missing anything if you're still willing.

Looking online it doesn't look like my ECU resets like the e36. I unplugged the battery last night and am letting it sit all day today. Will try again tonight.

As for the smoke test I just modeled it after these two posts. I put a hole in a soda can and the can fits nicely into the intake hose. Just tape it and seal it off good before putting smoke into the system. Dont forget to open the throttle.

http://www.r3vlimited.com/board/showthread.php?t=292791&page=2&highlight=smoke

http://www.r3vlimited.com/board/showthread.php?t=274418&highlight=smoke

cpandrewschmidt

hooked the battery up again and turned on. Still sputters like before. Still bad enough that its definitely not right. I have no idea. Ugh.

I'm thinking this still might go back to those Bavauto performance wires and plugs. I did find one buried topic online of a person having issues with those wires.

Is there anyone I could meet up with that has an m20 engine that would be willing to let me try their plugs / wires to rule that out?

Thanks again for every ones help here. Oh, I did also hook the vacuum test back up and I got 16-17 psi, so that was much improved from before and where it should be.

jc43089

Is the vacuum gauge steady?

I have some i wires that are used but worked fine. I work with a guy from Mount Horeb, he could probably get them to you on Sunday maybe.

YoungCR

My new wires came from ECS but I won't be around this weekend. Not sure what brand they are yet. I think I rememeber hearing some issues with Bavauto wires too.

Boris3

Sorry to hear it's still not cooperating.

I've got an old set off my 90 325i you can try if anyone is heading Madison way from New Berlin/Milwaukee.

cpandrewschmidt

Thanks JC - sent you a message. I can meet up today after noon or tomorrow if possible to grab those.

cpandrewschmidt

Ugh, frustrated. Changed out the wires (thanks JC) and put in some NKG plugs just in case. Still getting the same problem.

Out of ideas

B C

Afm

jc43089

Snap, what happens with the afm unplugged? Does it use default safe tables? That could be a way to test by trying to run it with the afm unplugged.

Jdesign

I am in Madison and am more than willing to take a look at your car. I am sure we could get to the bottom of this in a few hours. You should compose a list of everything you swapped out or replaced in attempt to diagnose the problem. Shoot me a text and when you have time, swing by my shop and I can help you get this sorted, like you said, I am sure its something simple.

414.eight52.five943

cpandrewschmidt

Thanks guys, you all rock for offering to help like this.

I've tried unplugging the AFM and the car just stalled and died so I'm not sure it can run without that plugged in, i don't think so.

I'm going to try cleaning the AFM tonight and moving the track slightly on the electronic sensor like this guy does. I opened it up and I definitely have two distinguishable spots of wear along the track.

http://www.r3vlimited.com/board/showthread.php?t=247831

I don't totally understand how the AFM works but this might be it. The thing I don't understand is does that arm constantly move along the senor pad, or does it only adjust while pressing the throttle? If it's the later I don't think that'd be my issue because the car sputters even when in idle. However, if that arm is constantly moving based the other sensor in the air box it'd make sense for the car to sputter when it hits the dead spots along the track.

Either way, I'll report back tonight!

jc43089

When there is more air moving through the afm it opens then flap which is linked to the wiper. The cross section inside of the afm increases as it opens so it will open in a somewhat linear way through the range of airflow. The air is based on how far the throttle is open.

cpandrewschmidt

Hi all, quick update. Snap looked and tested my AFM. did show signs of dead spots. So, since i didn't have a new one I just put it back in and also re-swapped out the OEM wires and plugs back to the newer performance ones / bosch plugs. So, all the same stuff.

I was going to meet John Thursday in Cottage Grove to look things over. I wanted to make sure I could make it that whole way from the westside so I took the car out Wednesday night to my wife's Happy hour just to make sure it woudn't die. It sputtered for about 2 mins then settled down. I hit a detour on my way which made me have to go 70mph on 151. Took me about 30 mins to get around town. Car ran great, no issues. Let it cool down while we ate for several hours. Fired it back up on the way home. No sputtering at all.

So, Thursday I decide to try taking it to work along the Beltline. Fired it up, no issues. Drove around all day Thursday and took to work again today. I'll probably jynx myself for typing this, knock on wood, but no issues. Nothing different that i did. So, no idea but I'll take it for now! I'm not touching anything Actually have a few drips i have to stop, but at least I feel I hopefully wont break down.

Just wanted to say thanks again for everyone's help. I definitely learned a lot about this engine through all this.

Andrew

Earl

You learned that m20's can't be trusted and it needs an m50 swap right?

cpandrewschmidt

Earl said:

You learned that m20's can't be trusted and it needs an m50 swap right?

Ha, yes. Maybe when this one dies.

straight6pwr

Glad you got it solved.

WIBIMMERS

1991 325i m20 help, madison