Grrr...Frustrating Idle Problem!!

[Victor_PR]

I am soooooo frustrated with my car!!!! I recently had a head gasket job done - including the reconditioning of the head. Bringing her home from my mechanic's house/shop she had a rough idle at stops with CEL turning on. Once I throttled her the CEL disappears and she runs good. I had noticed difficult in braking (as if the Brake Booster wasn't doing its job) and I took her back for a BB change hoping that with it's replacement the idle problem would improve (I even had a new Exhaust Pipe installed because mine was shot), again, hoping for the sought out miracle of the idle (and hot start difficulty) to disappear - didn't happen!
My mechanic - btw, very respected here in the island by us E30 freaks - wasted a can of carburetor cleaner trying to find the leak but nothing. I did the Stomp test and got the 1222 code. A friend of mine lend me his R5/FCX scan tool and it confirmed the 0A Lambda (Emission) Control at fault. My mechanics guess is the AFM. I removed the cap on the AFM and started the car. As she idles I could see the brass wiper contacts oscillating (not remaining fixed in one place). I moved the wiper arm assembly towards the left and the idle improved. If I moved to the right, the car wanted to turn off. As you can see in the picture, the wiper contacts travel prints are quite obvious hence makes me think that my mechanics diagnosis could be right. I know the smoke test is going to show up in the responses. However, not a common diagnostic tool for the shops near by. I'll keep searching. I even borrowed a fog machine and tried to search for the leak but my untrained eye did not reveal anything (even the vacuum cleaner tube I used as an extension for the test melted - duh!! It's hot fog that's coming out!) Sorry, my frustration calls for my self-insults!
I had a '87 eta with the same idle oscillating problem. The fix: I drilled a 1/4 inch hole in a penny and placed it inside the vacuum hose that connected to the ICV. Ran like a charm.

If I don't come up with the root cause for my problem soon I'm going to have to let the car go to someone else - something I don't want to do because I love E30s but having the car useless is simply out of the question - at least that's what the wife says.

Anyway, thanks for hearing me out. I'm sure I'll be sent to the Search files and that's ok. I feel a little better now that I was able to get it out of me.
Thanks for reading.

[ELVA164]

Did you replace the O2 sensor? That would be my only suggestion other than trying a replacement AFM.

[mikeedler]

It is def. an intake leak. Just pull the complete intake back off and check everything, stick it back on. It really isn't a hard job at all. could be the cross over tube o ring on the bottom of the intake to some really easy hose not seated correctly. The fact that you aren't building vaccuum boost for the brakes is a def. giveaway of the intake side leak.

You are getting an O2 fault because of the intake leak. If the motor is sucking in too much air, it can't get the correct AFR.

[jlevie]

Everything in the description of the problem is screaming INTAKE LEAKS. The chances of finding them with carb cleaner or a visual inspection is nill. You have to find a shop that can do a smoke test.

[Victor_PR]

Did you replace the O2 sensor? That would be my only suggestion other than trying a replacement AFM.

Just before the head gasket problem, I had replaced the O2 sensor with a new one.

[Victor_PR]

It is def. an intake leak. Just pull the complete intake back off and check everything, stick it back on. It really isn't a hard job at all. could be the cross over tube o ring on the bottom of the intake to some really easy hose not seated correctly. The fact that you aren't building vaccuum boost for the brakes is a def. giveaway of the intake side leak.

You are getting an O2 fault because of the intake leak. If the motor is sucking in too much air, it can't get the correct AFR.

The most I have personally removed is the the Air Box all the way up to the L-shaped rubber boot and the ICV. This was pretty easy so I'm gathering you may be meaning that there's more that needs to be removed. What else could it be?

[dnguyen1963]

Check the elbows going into the throttle body. A common intake leak point.

[flyboyx]

i agree with the likelihood of an intake problem. i had an 87e that ran like you describe. it turned out that some jackass previous owner had replaced the afm and installed the wrong one for an e. i found the correct afm at a junk yard, changed it out and the car ran perfectly after.

[Victor_PR]

Update

Hi everyone;
I replaced the breather hose that goes from the valve cover to the throttle body underneath the manifold. I replaced my AFM with a reconditioned one from Greg. I just finished correcting an exhaust leak at the muffler shop. Car has improved significantly but there still remains the traces of an unstable idle.
One thing I recall when I first bought the car is that a friend of mine tweaked the little screw type tip next to the throttle cable. I learned in my idle problem research that you're not suppose to mess with this screw (I didn't know this then so too late!).
Could this have anything to do with my idle problem?
Next to check is the FPR.
Thanks for hearing me out!

[Bmwb]

did you try dele the code... took me a while to figure out i had to and my car ran like shit , but right after i reset it it never came back on , but i had to do the battary pull for a few to reset it

[jlevie]

Hi everyone;
I replaced the breather hose that goes from the valve cover to the throttle body underneath the manifold. I replaced my AFM with a reconditioned one from Greg. I just finished correcting an exhaust leak at the muffler shop. Car has improved significantly but there still remains the traces of an unstable idle.
One thing I recall when I first bought the car is that a friend of mine tweaked the little screw type tip next to the throttle cable. I learned in my idle problem research that you're not suppose to mess with this screw (I didn't know this then so too late!).
Could this have anything to do with my idle problem?
Next to check is the FPR.
Thanks for hearing me out!

Messing with the idle stop could affect idle stability. If the idle stabilizes when you unplug the TPS you can try adjusting the idle stop. With the engine at normal operating temperature unplug the ICV and adjust the throttle stop for an idle of 900-950rpm. Then adjust the TPS for the idle switch to close when the throttle stop arm is 1mm off the stop screw. With the ICV re-connected the idle should stabilize at 750rpm.

Before doing this you need a smoke test to prove there are no intake leaks (or to find them so they can be fixed). Any unmetered air will invalidate the adjustments.

[Victor_PR]

did you try dele the code... took me a while to figure out i had to and my car ran like shit , but right after i reset it it never came back on , but i had to do the battary pull for a few to reset it

I should have included in my update that I had reset the CEL with the Peak Reset Tool before installing the rebuilt AFM. The CEL has not turned on after the things I mentioned above.
Could my DME need time to interpret and "get used to" the new AFM?
Nevertheless, I suppose it won't hurt to do the Disconnect Battery Reset approach you are suggesting.
Thanks!

[997_rich]

Also you might want to check the valve cover gasket and the oil pan gasket. If they are torn or leaking those are vacuum leaks.

[shadowracer]

Try checking the ground strap at the oil pan going to the frame, I had a very similar issue with a R5 tool used as well. It showed a sensor was bad, well I had replaced all sensors in the car and still nothing fixed. In the end a friend mentioned the ground issue, low n behold we checked the ground and it was loose, we tightened it, and all the issues went away and the car ran perfect again!

...Good luck!

[rodpaine]

Snip... In the end a friend mentioned the ground issue, low n behold we checked the ground and it was loose, we tightened it, and all the issues went away and the car ran perfect again.

Yup, ground connections on our old BMWs create quite a few problems that many DIY's don't look for. It's why I put this ground point list together, which has helped solve a number of strange problems. And here is one that I've seen on more than a few E28s, creating a hand full of running problems. Take a look at these.
-Rod