yet another rough idle thread.

[doctorx69]

This one is a little different that i have been reading. I read the faq and wondering what i am missing. This only started when the temp got to 50ish or below.

When i first start when cold, it acts like it is missing for about 15 secs. Then it smooths out. I dont notice any problems after that. Idles around 900-1000 and will hunt between 900-1100 on occassion. What i have tried so far: smoke test (although going to do it again). If i pull the dipstick while engine running, it slows way down until i put it back in. I am not convinced of vacuum leak. Going to test TPS. Clean ICV again with carb cleaner. I am wondering if the ASM needs cleaning, however, i read that could be full of dragons.

What else can i try? I thought about pulling throttlebody and put a new gasket on, however i would have thought that would show up in smoke test. New hoses were put on last April.

I am going to dive into it this week and would like the e30 gods to let me know what else to check? I am stumped at this point. If there is a doc or post i missed, i am all ears!

[sienayr]

Try resetting the throttle body adaptations and see if anything changes. Turn the key to ON for 30 seconds, you should hear the throttle body click. Turn the key off, then fire up and see if anything is different. (I'm assuming here the 6cyl model works the same way as V8).

[doctorx69]

Thanks ill try that.

[sienayr]

Man I apologize, I got my forums mixed up. This is for an e39, I thought I was in the e39 forum. This won't work for an e30.

[doctorx69]

bummer

[ZeroDarkE30]

injectors clogged, valve cover oil cap seal, spark plug #6 sensor? just spit balling some things to check out

[doctorx69]

new injectors. new fuel regulator, pumps, tank, filter. new valve cover oil cap. new plug wires with #6 sensor connected to harness. now you know why i am stumped.

[doctorx69]

i have ngk spark plugs... but i doubt that is the problem.

[ZeroDarkE30]

yeah i mean at this point i would just pull the Throttle body clean it real well and reseal it. Check the little elbows that connect in there for leaks too since they are kinda just press fit in there and u cant find them to replace anymore. Let me know what you find though because i have a rough idle too but car hasnt run in a couple months so once its back together my hunt begins.

[doctorx69]

i may do that... also ordered new plugs. I am suspecting maybe the gap is wrong? I read several different places several different gaps. Bently says .028 for my 325i. I am going to change the plugs first then see how the cold start is. Yea, i have been wondering that. Also, that throttle body cooling loop is leaking. There isnt much i can do there so i may have to just bypass it like it was when i got it. A new throttle body is a bit expensive.

[doctorx69]

actually... the more that i think about it, it may be those side connectors on the throttle body. Bone cold could make them have a leak and when the metal starts to warm, it would seal. I wonder what would be good to seal it?

[sienayr]

But... you should have seen smoke seeping out during your smoke test.

[doctorx69]

true.... another forum mentioned the AFM may be shaky..... not sure about that one... opinions? Someone had the exact symptoms and new afm fixed. I would like to eliminate others first.

[sienayr]

If you can find a local bmw facebook group or know someone with an e30 then you can swap a different one in and see if anything changes. or maybe a salvage yard will have an e30 if you're lucky.

[superj]

I seal the elbows with rtv

the afm can be tested with a multimeter on the pins for the plug. if its not smooth, then you can pop the black top off and bend the wiper arm a little so its sliding on a part of the board that is not so worn. people have had luck doing that

[doctorx69]

in my little corner of the country... they cannot spell BMW... unfortunately.

- - - Updated - - -

ill get my multimeter out and test. thanks.

- - - Updated - - -

which rtv? clear?

[superj]

Any. I have used black, grey, orange, red

[actletpone]

Coolant temp sensor? Does your car have a cold start valve?

[doctorx69]

new coolant temp sensor... i dont think so on the cold start valve. One thing i did was took multimeter to icv and it checks out. Didnt get a lot done this last weekend. I will try to do another smoke test.

[doctorx69]

i got around and pulled the plugs... look fine. Regapped them to .28ish... scoped the top of the piston and saw a ton of carbon buildup. I guess i need to figure out how to seafoam this engine. I was looking for any liquid pooled on top of piston but it was bone dry. Right now working on the rear end and will come back to this after I am done.

[superj]

I put the seafoam, or just water, through the vacuum line for the fuel pressure regulator, or I just put it in the intake hose from the afm. either way gets it in and then it will kill all the mosquitos in the yard for a bit and clear up. I don't know if it changed anything but it did smoke out all the flying bugs

[doctorx69]

I know it works great on my 92 sonoma... just havent tried it on the bimmer yet.

[doctorx69]

ok... a new wrinkle... I have stated before that after 15 sec the engine runs fine. Just a little mist coming out on a cool morning until engine is warm then no water coming out. (have to wait until it gets warm to reconfirm)... I took the end exhaust off because of changing out bushings and driveshaft and when i lowered it, there was a bit of water that came out of the end that connects to the cat. Not a lot, but about 1/4 cup. I am done for evening, but gonna put in ear plugs (damn loud in my garage) and see if it starts up easier tomorrow. Starting to wonder if the initial sputtering is the exhaust choking engine until the cat warms up. At first i was scared that had a blown head gasket, however there is no coolant. Just water.

What would cause that? If it just running rich upon cold startup (which i heard these can and usually do), then i can live with it. Seems much worse after setting overnight. I am still going to pursue the other things still while i am wrenching on it. BTW, one more thing, the engine temp is always dead center when warmed up.

[superj]

moisture in the exhaust is fairly common because as the system cools, water in the air can condense in it.

did I tell you my Sonoma is dead. the kids finally did her in to the point that I gave up on her. we just have our 92 s10, now

[doctorx69]

no you didnt.... *bows head in silence*