$500 in parts- now have stumbling issue

[E30nate]

check the crank referance wheel. it could have slipped a little bit so the timing is off.

[bmwpower]

Did you guys mess with the gap on your new plugs?

The platinums (which I don't use) come pre-gapped. You neeed to gap the coppers.

[discnick]

I put my old cap on, one of the tabs were broken completely off but somehow it still manages to run fine, all cylinders sparking... Im going to replace it at some point but its not at the top of my list of things right now, and when I do i'll be ordering oem so hopefully I dont run into the same problem.

[mikekristine325ic]

bmwpower, what plugs did you end up using that solved the problem???
One thing that I will add: Sometimes I start it up when it is cold (and 25 degrees out) and the idle will waver about 200 rpm in rhythmic fashion, about one cycle per second. Then when warmed up, it will just stumble in random around -100 rpm, so little that it hardly registers on the tach.
I am doubting a vacuum leak at this point as I have scoured the engine with a tubed stethoscope, ether, etc. and have turned up nothing. When I pull the dipstick it immediately starts idling WAY WORSE. It seems electrical to me.

Same problem with my cabbie when I ran platnum. I am running Bosch Copper plugs and it runs beautiful!!!

As for pulling the dipstick, the engine is like a sealed unit. Taking off the oil cap or pulling the dipstick causes a vacuum leak thus idling crappy.

[bimmerboy12]

Just an update: I ordered Bosch Supers and will install this weekend. Can you believe I could not get Bosch Supers at Autozone, Advance, O'Reilly's, NAPA, Schraders, or Pep Boys??? Ordered from Bavauto. I will post an update at that time.

Anyone know what the proper gap should be?

Thanks

[bimmerboy12]

UPDATE:

I put in a new intake bellows and replaced the bosch platinums with bosch super +'s gapped to .030... didn't do a thing, still idles like shit.

I am gonna lose my mind.

[dr.strangelove]

i'm with you there. i have been having the same issues.

[bimmerboy12]

Ok, i had to revisit this thread to see if any of you found the source of this problem. I inspected my wire/cap area in the dark and saw no arcing. I can't tell you how pissed I am about this. Does anyone have a spare used cap that worked? I would rather pay for the shipping of a used cap then buy a new one that may still be faulty.
Seriously. Its getting f#$%ing ridiculous how long this problem has been going on.
Brian

[Naplm00]

i would swap in a known good AFM, i had issues like this and that was the culprit

[AndrewBird]

A lot of times the material they use to make distributor caps will have too high a carbon content. What this does is provide a ground, bypassing flow through the plug wires. Look carefully at the cap and see if you can find any small thin black lines (carbon tracks) running through it anywhere.

[bimmerboy12]

i would swap in a known good AFM, i had issues like this and that was the culprit

So the AFM randomly went out when I put in all these parts? Seems unlikely. I will remove and inspect the cap again and look for carbon tracks. I have also seen some cases on here where this type of idle issue can happen after a valve adjustment. Should I go back in and check the valve clearance?

[bimmerboy12]

OK, took the cap and rotor off and as you can see there is severe buildup on the contacts on the cap and rotor. notice the metal burrs rolled over on the cap contact. This is after installing brand new cap and rotor about 1000 miles ago this past summer. Both are Bosch and bought at Bavauto.
Your thoughts???

[bmwpower]

That's quite normal as you're transferring spark across those contacts. But now that you have them off, take some fine sandpaper and lightly sand the carbon off.

I think what other people were referring to were carbon "tracks" in other places inside the cap, like from an adjacent contact to another.

[Naplm00]

my afm failed one random day at a light

shit happens ?

[Mitchel]

#1: Why haven't you pulled the code resulting in your CEL yet? You're getting a check engine light.

#2: When you pull out the brake booster hose, does the car die?

This sounds like a vacuum leak to me. You'd know if this were a timing issue even if it was cold.