86 eta weird start/idling issues MIND BOGGLER

[scabzzzz]

Ill get right to it. I've been probing around and trying to figure it out in my head. The car is an 86 eta with m20. Has right about 200k miles, runs solid except for a few minor things.
The biggest issue is when I go to start it at times, it will start up and idle at or around 550rpm's. Kind slugging sounding but can sound normal, but always usually cuts itself off. With this same scenerio, I can feather the throttle and it pretty much WONT respond. When I crank it up, it'll come up and seemingly be idling fine, just a little under where it usually would idle and run perfect, yet when i mash the throttle to the floor, its like climbing slowly through the rpm's. If you leave it mashed to the floor, it will never hit more than 3k or so rpm. Sometimes it will also start up and idle like this, and barely hold itself afloat before dieing.

I know this doenst make a whole lot of sense. And it never does it when its cold. The cold start valve works great and ICV as well. The big kicker to it, i've almost figured out how to get passed it. If i start the car up, and its doing it, i immediately turn the car off and restart it. 7 times out of 10 it will start up great and idle at normal RPM which is about 900rpm. After I get it cranked up and idling properly, it runs and performs great for a car with its age. Its been overly maintained by PO's and this is my first E30. IM not a fan of the m20 but this is a daily right now. Its very reliable except for this one issue. I installed a new intake boot and fuel pressure regulator and it helped the overly running condition of the car but didnt really change much elsewhere. Any help?

CALLING J LEVIE!?!?!?!?
Some things i have in mind doing is ohming out the TPS, and fuel pumps and checking the fuel pressure at the rail. Possibly theres trash in the tank and the sponge is soaking of debris? Would that explain turning the car off and immediately starting it up to have it run good directly after the debri falls back to the bottom of the tank?
Like I said, its irregular when it does this. If i start the car 10 times a day during my routes, it does it maybe 3 times. Any ideas would be great from you guys.. and THANKS IN ADVANCE

[scabzzzz]

anyone?

calling Jim Levie!!!

after posting this thread, i went out to my car to start up and drive home from work. like to never got it started right. like it wasnt getting ample fuel or a relay was going awry.
btw, from PO, fuel pump and main relay were replaced little over a year ago.
anyways, Bumpsky

[jlevie]

The first thing I'd do would be to check the fuel pressure and operation of the fuel pressure regulator. What you describe could be a fuel delivery problem, bad AFM, or flaky DME. I'd start with the fuel system since there is a history of problems there.

[Garageaholic]

I Have The Same Exact Problem On My 325e. Same Exact Fuckin Problem!

[scabzzzz]

Yeah it seems like my buddy with a 325e in the same year gets the same problem. Yesterday as i was finishing out my day or whatever, i would start up and it would do it. so i cut it off, cycled the ignition a few times without starting it up, didnt help so its probably not a relay.

Jim: I replaced the fuel pressure regulator. It helped things a whole lot. I cant find any problems with the fuel lines. no cracking, no fuel smell anywhere. Another thing I noticed the past 2 days, when i go out to my car to start it up early in the morning, its like the cold start valve is failing. it doesnt rev high as normal. it just starts up and goes to normal operating rpm's.

I will report back with fuel pressure results. Thanks Jim, you're a life saver as usual with all my cars. :)

[scabzzzz]

I Have The Same Exact Problem On My 325e. Same Exact Fuckin Problem!

Dont worry dude, I'll get this shit sorted. I cant stand it when my cars dont run like they're brand new. So So OCD

[NABR 1337]

crank angle position sensor.

had the same thing with 2 of my cars. In fact that is how I got a 400 dollar cabrio.

[scabzzzz]

crank angle position sensor.

had the same thing with 2 of my cars. In fact that is how I got a 400 dollar cabrio.

Haha. Funny.

So about 400 dollars later i pretty much have come to the conclusion of AFM, crank position sensor, or throttle position sensor.

I've replaced:
-Fuel pressure regulator
-Known good DME with MarkD chip ;-)
-Coil
-Distributor cap and rotor
And tested this and that and plugged around for weeks. I'll stay tuned to this thread as I replace stuff. Ive got an AFM coming in today and Bilstein sports in my trunk :up:

Searching and searching yields similiar problems where the answer is all of the above. Soo good luck to those who find this in a search.

[frost_dxb]

any update? same problem here '86 325e

[scabzzzz]

Ok.. Heres a slight update.
Have checked the TPS, and its not the cause. Replaced AFM, not the cause although I did find out someone before me had the top off the AFM and it was hot glued down. Not sure what that was about.

Looks like its going to be coolant temp sensors.. and in my case, the one that sends the signal to the DME

Im banking on that.

[scabzzzz]

I spent a good while reading the Bentley the other night. Damn that book is really REALLY informative. lol..

[Restoman]

So what about the crank sensor. Are you talking about the on the front of the engine? ETA's have 2 additional sensors on the flywheel.

[scabzzzz]

Keep in mind this is my first e30 and i've owned it for about 2 months now.
Theres a TDC reference sensor i noticed when doing the timing belt. I dont think that has anything to do with that though.

My temp guage needle has been wondering since i bought the car at times.. still wiating on the parts to come in to figure it out.

[scabzzzz]

Update:

So last night I got my coolant temperature switch in.. I installed it and started it up. It started bad the first time.. Switched it off and tried again. Perfect start except it was shooting to like 1700 or more RPM and idling there and slowly coming down. I let it sit there for a sec and it started wanting to settle down to normal idle speed so it would try and then shoot back up to 1600+ RPM idling. I cut it off and tried starting it a bunch of times. Everytime it started fine but was idling uber high.. I drove to my friends house and popped the hood. At some point the screw on the idle speed valve was tampered with so i tried to reposition that to settle the idle down. It helped a bit but i have no clue what it was at from the factory. Now it just idles at like a thousand and smells rich..

What the hell...
No more crappy starts though lol. Gonna read Bentley again today at work to see if I can get another idea.. I half ass tested my throttle position switch before this as well. Idles the same with or without the switch plugged in. Have not ohmed out the reference or tps yet and i have not disconnected my battery to reset anything yet.

Any ideas?
Bump it up!

[jlevie]

The procedure for adjusting the idle stop and TPS is in your Bentley manual. But even if they are mis-adjusted they won't cause the problem you've described. It sort of sounds like the engine management system is going into limp home mode. And that could be caused by a flaky timing reference sensor, bad AFM, or a bad DME.