Will bad coils cause a high idle?

[DrinkCoffee]

Pretty simple question, but I can't find the answer on it anywhere (:mad).

I'm pretty sure 4 of my coils are bad. My car idles at 1,000rpm and the idle is rough with accessories turned on, randomly at a stop.

Could bad coils cause my high idle?:help

Edit: Issue fixed. Go here: http://forums.bimmerforums.com/forum/showthread.php?t=1513695 or pm me with questions of similar issues.

[JDStrickland]

Not likely.

Bad coils will cause a misfire, but this is 1.) reported by the Check Engine Light ('96 and newer), and 2.) would give a slow engine, not a fast one.

If you had four bad coils, you should have a Check Engine Light (SERVICE ENGINE SOON, I think it says) with diagnostic codes of P03nn, where nn is the number of the cylinder(s) with the bad coil(s).

[Automaticftp]

I'm not sure your car would run with 4 bad coils . . .

Replace your spark plugs and clean your ICV, check your fuel filter, etc.

[Trbulnt]

Check all vacuum lines!

[DrinkCoffee]

Vacuum lines are fine, vacuum is at 20" steady

Fuel pressure is fine, at 44psi. Fuel injectors are good.

I have code 1221 (oxygen sensor) because the car is running rich. I assumed that the car is running so rich because the coils aren't functioning properly and not igniting all fuel.

I've done just about every maintenance item you can so far. ICV, fuel filter, o2 sensor, plugs, valve cover gasket, etc.

I have fuel injector filters and orings coming even though they look ok.

[JDStrickland]

Vacuum lines are fine, vacuum is at 20" steady

Fuel pressure is fine, at 44psi. Fuel injectors are good.

I have code 1221 (oxygen sensor) because the car is running rich. I assumed that the car is running so rich because the coils aren't functioning properly and not igniting all fuel.

I've done just about every maintenance item you can so far. ICV, fuel filter, o2 sensor, plugs, valve cover gasket, etc.

I have fuel injector filters and orings coming even though they look ok.
The car can be rich because the MAF is lying.

The MAF measures air temp and density to maintain the perfect ratio of 14.7 parts of air for each part of fuel, but if the air is dense and cold or warm and thin, and the MAF isn't detecting this properly, then the fuel delivery will be out of whack, and the O2 will detect this and tell the computer to make adjustments. The problem is, the adjustments will be all over the ballpark, and the O2 will eventually give up trying to get the mixture right, and report the error.

A weak spark should appear to the computer as a misfire, but a misfire doesn't mean that the plugs didn't fire. For each firing of a plug, there is an expected amount of work to be performed. This work is measured by the Crank Position Sensor -- if the work exists, then the CPS pulse will be x-time away, but if the work isn't as expected, then the pulse is y-time away. A lean condition is typically caused by the MAF, and random misfires will be called out in this instance.

I'm not sure what the rich condition is that you are reporting, but I'd not expect an issue with the coils, and certainly not 4 of them AND you can still drive the car.

[DrinkCoffee]

Well, the reason that I say the coils are bad is because I had to take the car to a mechanic a few months back. He said that 5 of the coils were reading oddly and that 3 were especially bad. I was on a budget at the time and replaced 2 of the bad ones with new ones. The car wouldn't start before replacing the 2 coils, but ran fine afterwards.

I guess I misspoke and 3 of the coils are still bad. Since then I bought used ones that were said to be in working condition which I put on. I think that they still may be suspect.

I think that the maf is good, because when I unplug it there is a major change in engine idle to the point where it may even stall. Once plugged back in, the idle returns to ~1,000 and is slightly rough, worse with accessories on (a/c, headlights, rear defog, etc.).

The [new] plugs also are wet when pulled. The oxygen sensor is still reading rich at idle and while driving, too.

I can't think of many things that would cause a rich running condition and a high idle, which is what has been making this so frustrating for me.

The only things that I can think of are leaking injectors (my injectors looked fine, and fuel pressure is perfect), ECT sensor (reads perfectly when tested), or possibly the air intake temp. sensor.

I haven't tested the AIT yet because it is in a very hard to get to spot (under the manifold near the firewall). I haven't yet had time to pull the intake manifold, but I'm eager to test the sensor and will hopefully be able to tomorrow.

[DrinkCoffee]

Well I tested my Air Temp Sensor and ECT sensor yesterday, and they are both working fine. I also messed with the TB some more to no avail. I have no idea what the problem could be now, but I have some new coils on the way.

Perhaps the ECU is bad? Any way to check?

[Seeker]

your ICV may still be sticking..

what procedure did you do when you cleaned it?
what did you spray into it to lube it?

[DrinkCoffee]

Awesome, thanks much for the reply.

I wasn't aware that I was supposed to use some kind of lube, actually. Someone told me to spray the hell out of it with TB cleaner, which seemed to work.

I had it out yesterday and checked to see if it was still moving easily, and the valve felt very flaccid and mobile.

What would be okay to use as a lube? I would definitely do that when I have time on Wednesday. I actually bought a used ICV also, just to check if there was any change in idle without blowing the 170$ on a new one (no change). But perhaps the used one is bad.... damned used parts and second guessing them.

[DrinkCoffee]

Well, my new coils should be here today, and I'll probably refurbish my injectors since the kit for that came also.

Anyone else know what I should be lubing my ICV with?

I'll keep this updated for anyone else running rich with a high and rough idle.

[NCbimmerman]

Do a search on here for "rough idle." You'll find a list of things to check before you add on the new coils. I would start by checking the vaccuum lines and spark plugs.

[Seeker]

I lube ICV's with silicone spray

[gmak]

And........ he never came back and updated. Did the new coils solve the problem? Did he find happiness with the silicone lube?

[rajicase]

^^Gotta love those threads that never get resolved >.<

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And........ he never came back and updated. Did the new coils solve the problem? Did he find happiness with the silicone lube?

And I just LOLd :D

[atlantisvip]

It's not about adding lube to the icv. people say to add wd40 and other crap. DONT!! People here are guessing and throwing shit at you without knowing what the fuck is really happening with your ride. A bad/sticky ICV will give you erradic idle, THATS IT!! High idle seemsto indicate vacuum issues. Hoses may look fine but there can be hairline cracks anywhere. Tear down your upper intake, fuel rail and injectors. If I was like these guessing fools I'd say something like FPR or fuel filter. I really don't know what the fuck is going on though. Search every related thread, same people working up their posts spitting the same crap. You ever consider you could have low compression on a cylinder?? That is actually one of the main reasons on bad idles and random misfires. Start there. You're welcome.

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And what does coils reading oddly mean? Mechanic is a moron.