Hey everyone. So I've adjusted my valves, gotten my timing together, and have adjusted the air/fuel mixture to where its not backfiring all the time or "popping".

Problems still exist: My idle adjust screw is at its tightest but it still is idling too high. Any adjustment with the A/F ratio causes backfiring/popping, and where its at now seems really rich (heavy gas odor in the exhaust). Also, on a cold start the idle is erratic, going up to 2-2500k and back down around 500k or even threatening to die at times unless I give it gas. Once its warm it doesnt do that but its still high, around 1300-1800k

I've done my best to seal off any vacuum leaks and route the lines to their proper places. Or at least I think so.

Thanks again..........

A lot of people cant figure out how to adjust the idle, so they adjust the throttle cable or stop screw, which is factory set. You say your idle screw is adjusted all the way in? From here, adjust the throttle cable until the car is idleing at 650rpm. IF its not the cable adjust nut, then it's the throttle stop. Adjust it so that your idle is at 650. The open your curb idle screw until you see 1Krpm. Then your throttle cable is in adjustment and so is your minimum air. Then set the mixture. Do all this with the car warmed up if possible. And yea, double check for air leaks!
John

really check for vacuum leaks, you've probably heard it a bunch before but it sounds like you are getting more air through than you should. Have you checked your air intake boot? Sometimes that could be cracked or be loose.

A lot of people cant figure out how to adjust the idle, so they adjust the throttle cable or stop screw, which is factory set. You say your idle screw is adjusted all the way in? From here, adjust the throttle cable until the car is idleing at 650rpm. IF its not the cable adjust nut, then it's the throttle stop. Adjust it so that your idle is at 650. The open your curb idle screw until you see 1Krpm. Then your throttle cable is in adjustment and so is your minimum air. Then set the mixture. Do all this with the car warmed up if possible. And yea, double check for air leaks!
John

Could one of the sensors cause a high idle?

All the sudden I'm idling at 1100ish and I had to turn the idle screw all the way down to get to 950ish. I have checked for vacuum issue and I don't have one. I noticed the other day when my car was idleing at the correct rpm that the engine was - how should I say - wavering/hunting up and down about 50 to 100 rpm - back and forth.

I don't think that adjusting the throttle cable is the fix here.

Feedback??

Thanks,
Rob

There are no sensors except the O2 sensor. Nothing can cause a high idle except more air going into the engine. All 320i's have vacuum leaks, so if you think you don't you aren't looking hard enough. The area where the valve cover pipe goes into the intake boot is very hard to seal and commonly overlooked due to its difficult location. If it happened all of a sudden a cap may have fallen off. There is a large one under the manifold that is commonly missing.

There are no sensors except the O2 sensor. Nothing can cause a high idle except more air going into the engine. All 320i's have vacuum leaks, so if you think you don't you aren't looking hard enough. The area where the valve cover pipe goes into the intake boot is very hard to seal and commonly overlooked due to its difficult location. If it happened all of a sudden a cap may have fallen off. There is a large one under the manifold that is commonly missing.

Hmmm, very interesting - what kind of cap are you talking about and where do I look for this??

Thanks,
Rob

do you run a high flow air filter (k&n etc) without a prefilter? or other aftermarket air intake components? reason being you mension rich odours and afterfiring symptoms. cis air metering system is highly suseptable to binding due to debris between the metering plate and the throat. also after checking waferman's suggestions and if the problem still presists check for gum buildup in the throttle butterfly...very common problem. by the way there is no miricle in a bottle to fix this, it has to come apart and be cleaned with a carb cleaner or straight gasoline. this is a good idea even if your car is running ok to begin with.

do you run a high flow air filter (k&n etc) without a prefilter? or other aftermarket air intake components? reason being you mension rich odours and afterfiring symptoms. cis air metering system is highly suseptable to binding due to debris between the metering plate and the throat. also after checking waferman's suggestions and if the problem still presists check for gum buildup in the throttle butterfly...very common problem. by the way there is no miricle in a bottle to fix this, it has to come apart and be cleaned with a carb cleaner or straight gasoline. this is a good idea even if your car is running ok to begin with.

Hey Auto,

Sorry to confuse - I don't have those problems. Also, I have a stock intake with fuel injection.

I'm going to investigate a vacuum leak (again) tomorrow. I'm waiting for Layne to tell me where this cap thing is that I should be looking for.

Thanks,
Rob

(later models only) See the square-ish part of the manifold with the BMW logo on it? Reach under the bottom side of that and feel around. There are two little pipes sticking down towards the ground. One is about 1/8" diameter and has a line to the distributor. The other is about 1/4" diameter and has a rubber cap on it, if it didn't get lost.

(later models only) See the square-ish part of the manifold with the BMW logo on it? Reach under the bottom side of that and feel around. There are two little pipes sticking down towards the ground. One is about 1/8" diameter and has a line to the distributor. The other is about 1/4" diameter and has a rubber cap on it, if it didn't get lost.

Ah, these are right beside the idle control screw. I'll take a look in the morning. I have the square-ish piece.

Thanks for the info.
Rob

No no no, other side. Stand on the left of the car.

Here's an old pic of my car that shows what he's talking about.

There were 2 red vacuum lines coming out of the bottom of the intake manifold on my car, the one toward the front is connected to a larger dia short black hose. This vacuum line is part of the hard warm start dealer installed recall. If you don't have a piggyback black wiring harness and an extra blue plug and brown plug at the thermo time switch and cold start injector, then this port should have a vacuum cap on it. If it's missing or cracked you can guy them at autozone.

http://i25.photobucket.com/albums/c58/jrcook320/My%20E21/82f8.jpg

Hey Guys,

Thanks to you both for the clarification. I'll be checking it out in the morning and I'll let you know.

Rob

I just checked and the plug is still in the end of that vacuum tube - so now what? :rolleyes

Can I make my own vacuum tester or do I need to buy a kit? Also, where do you put the tester in-line to get the vacuum reading and what should it be.

If it's not a vucuum problem where should I look next?

Rob

You talking about a vacuum gauge? Thats not going to help at all. The best way is not to test for leaks but to act as if everything leaks. Replace all the hoses, check and reseal everything. If you must test some like the carb cleaner trick but I like to get a small tube a couple feet long and hold one end right by your ear and move the other end all over the hoses. You'll be able to hear if something is leaking.

You talking about a vacuum gauge? Thats not going to help at all. The best way is not to test for leaks but to act as if everything leaks. Replace all the hoses, check and reseal everything. If you must test some like the carb cleaner trick but I like to get a small tube a couple feet long and hold one end right by your ear and move the other end all over the hoses. You'll be able to hear if something is leaking.

Ya, vacuum gauge. Is vacuum leak the only reason that I might be having a high idle issue - it's not some sort of sensor or the need to adjust the throttle cable?

Rob

There's only one thing that can make your engine faster and that is air. I can't tell you if its getting past a partly open throttle plate, a stuck aux air valve, or a leaky hose. You'll have to check all these things yourself. Some commonly overlooked items are: the rubber hose at the bottom of the dipstick tube (yes that is a vacuum leak); the hose and plastic coupling that go into the intake boot way down below the manifold; the boot itself; the hose below the aux air valve.

(later models only) See the square-ish part of the manifold with the BMW logo on it? Reach under the bottom side of that and feel around. There are two little pipes sticking down towards the ground. One is about 1/8" diameter and has a line to the distributor. The other is about 1/4" diameter and has a rubber cap on it, if it didn't get lost.

Hey Layne,

Can you clarify something for me? I just noticed that the distributor line actually goes to the connector right beside the throttle adjust screw on the passenger side.

The 1/8" line you talk about above goes to the t-junction in the just above the valve cover..... :rolleyes

This seems to contradict what you're saying. Are my lines crossed?
Rob

I've seen that before. I can't say why they're switched or what difference it would make if any. It appears that JR's lines match yours, so maybe mine were wrong? It worked though.

One other thing: theres a line there near the idle screw that goes to the charcoal cannister, which almost certainly leaks at some point so its best to just put a cap on that one.

I've seen that before. I can't say why they're switched or what difference it would make if any. It appears that JR's lines match yours, so maybe mine were wrong? It worked though.

One other thing: theres a line there near the idle screw that goes to the charcoal cannister, which almost certainly leaks at some point so its best to just put a cap on that one.

Hey Layne,

I'll check it out. You may be the odd man out on the vacuum line routing but if it ain't broke don't fix it right :)

Thanks,
Rob

hey, not sure if you guys are still checking this thread, but if the charcoal canister only has one line going into it from the engine and where there is supposed to be a hose on the top connection there is nothing, could that cause a high idle?