1991 318is m42 idle problem (SOLVED)

[Sage91-318is]

    I've had this problem for a little over a month now. It all started when I was feeling ambitious and wanted to fix a minor idle problem. This minor idle problem was when I turned on anything electrical (like the heater) my revs would drop a little, then immediately go back up. Keep in mind it was running fine at this point. I did a little research and thought it might be my IVC. After I cleaned it, and put everything back together, it'd idle erratically between 600-900 revs. If I gave it any gas, it would rev up then turn off. Thus making my car undrivable.

   I replaced the ICV, thinking I ruined my last one. That did nothing. Proceeded to replace the intake boot, the intake manifold gasket, and fuel filter. All did nothing. Then I got frustrated and decided to take it to a credible local shop to get diagnosed. This shop has been in business for over 20 years and only works on European cars. They tell me I need a new AFM and the hoses are wrong in the intake. When I got my car back from them, the idle problem changed. Now when I go to turn on my car it'll rev up and immediately turn off.

   I replaced the AFM, that seemed to do nothing. I haven't put in new hoses yet because I think they're the result of the previous owner doing the heater delete and the shop isn't aware of that (they claimed they were though).

   If any clarification is needed please let me know. I'm also happy to take pictures or video if necessary.

[deansweet]

Seems like you have done everything that needed to be done.
Maybe a smoke test on the intake to see if you have any old worn or cracked hoses?

[Sage91-318is]

I'll do that next. I also think the AMF I ordered was too cheap, so I took the hit of ordering an OEM one and I'll post an update of how that goes. Should be early next week.

[Sage91-318is]

Okay, ordering an OEM AFM did nothing as well, which really bums me out. I plan on doing a smoke test now. What is the best way to go about doing one?

[E36-italia]

I plan on doing a smoke test now. What is the best way to go about doing one?

Smoke some weed? 

[Sage91-318is]

.... Well I do live in Colorado and I am over 21, so I don't need to worry about the cops. All I have is a hookah, I'll try to make that work.

[Tgoode318]

If you want to do a "ghetto" Smoke test you can use Carb cleaner. With the engine on, spray around all of your hoses with carb cleaner and listen for a change in idle.. It should be a pronounced change in RPM.. While not as good as a "smoke Test" this has worked for me a number of times.
It's not uncommon to work on the icv,air intake, etc put it all back together and then have every thing become worse. This is usually because the hoses are so old that when you remove them they put cracks/air leaks all over the place. 

Also do a "Stomp Test" and report back with any codes you get.
http://www.pelicanparts.com/BMW/techarticles/Mult-Code_Reading/Mult-Code_Reading.htm

[monty23psk]

Reading your posts, I believe something is unplugged or the hoses are not installed correctly.

Also, from your first post, when the car is idling, and you turn the AC, not sure if this is what you meant by heater, the idle will drop until the ICV kicks in and brings the idle back up. I believe nothing was wrong unless this was happening with anything electric, like your lights, radio, windows, which you stated. I would need more clarification if I was your mechanic.

Then when you cleaned the ICV and put it back the idle was erratic, this means the hoses are not on correctly or something like this as you have an intake leak or you damaged the ICV during the cleaning process. That is my opinion of course from working on these engines for over 7 years.

Now after theshop looked at it, it seems to be worse. Normally during these troubleshooting steps, things stay the same, might get better, but if something goes bad, you should be able to rollback what you did to return it back to the status quo. If it does not, then things are getting damaged along the way.

Another option is to light up a tobacco cigar, remove the valve cover vent hose, towards the front of the engine and blow that smoke in. Just get a good body cigar.

[deansweet]

I'll tell you how I did mine?
Take a tennis ball, cut out a hole just big enough to place one of those smoke bombs things from the 4th of July, any color smoke will do. Cut a slit 180 from the big hole.
light the smoke bomb and place inside the ball, place in intake rubber and take your compressed air hose with blow tip installed and put a small amount of air thru the small slit. Be careful not to blow the bomb out of the tennis ball.

Ghetto engineering at its best.

Dean

[Sage91-318is]

I was afraid I installed it incorrectly, but then I tried to put the hoses together in a different way, and it simply didn't work. If I anybody has a picture of on E30 inake setup with the heater delete, I'd really appreciate it. I did put a hose clamp the hose going to the intake boot. Now the idle has changed to reving between 400-1000 rpms, as oppose to reving between 600-800. It's also revs slower than before. Does this mean I'm on the right track? Again I do plan on doing a smoke test I just haven't found time to throw something together and do the smoke test.

[monty23psk]

Check my thread, not sure what page. Or you can check the tread on the heater plate delete under the general section. Any idle seeking is not good. The ICV has only one way to be installed in the the air from the intake boot flow in once direction to the rear valve cover inlet. There is an arrow the show the flow. The hoses only really go in one way and there are two section only if you remove the heater plate. Check those threads out.

[Sage91-318is]

Okay I feel I can finally update. I've also done everything I felt I can do. Allow me to recap. I replaced the ICV, intake boot, all of the hoses, fuel filter, intake manifold gasket, throttle body gasket, air flow meter, and spark plugs. I did a smoke test, but it wasn't a very good one. I did it with a paint can and , but I couldn't get the paint can to seal so not much smoke went through. I did see some smoke come from the ICV area. Because of how little smoke I was able to pump through the intake system not much came out, I wasn't able to pinpoint an exact source. I even bought a diagnostic tool, no codes came up. Other than that, I have no idea what to try next. I'm open for ideas.

[Tgoode318]

Spray carb cleaner around and listen to changes in the engine?? If nothing changes next i would check your electrical system make sure your bat and alt are up to snuff and your relays are all in good shape.  And no codes either huh? intake leaks will usually throw a code but pesky electrical probs might not. my 2c

[Sage91-318is]

I finally solved my problem! It turned out to be a vac leak. I was able to get my friend who's a savvy mechanic. He pointed out that I installed the ICV wrong. I put the clip (not sure what it's called) that connects the ICV to the engine under the intake manifold, thus leading to a vac leak. I'm not sure if that makes sense, but the point is it was a simple fix. It's kinda embarrassing how simple of a fix it was for my problem, but then I remember the reason I got an E30 was so I could learn how to fix cars.