$500 in parts- now have stumbling issue

[xLibelle]

durring a recent service, i purchased a Beck&Arnley just to get the job done while away from home. I have been a couple hundred miles since and no issues yet.

[bmwpower]

No, i didn't disconnect the battery for servicing since I wasn't dealing with any live leads.

I have driven the car back and forth to work 14 miles round trip every day since performing the service about three weeks ago. It runs perfectly fine and normal with the slightest increase in gas.

AFM is plugged in and I have unplugged/plugged nearly every connection under the hood looking for a loose connection... no luck.

Try disconnecting/reconnecting the battery.

[bimmerboy12]

No kidding! That is bizarre. I am going to do the same thing and see if i get a similar arc. Who would have ever thought... I will let you know asap. Good luck and many thanks for the great info! Let us know what happens with the new cap.

So i figured out my issue... My duralast distributor cap from autozone was grounding out the #2 spark wire... I reinstalled the cap without the plastic cover and to my surprise I could clearly see the lightning bolt jumping from the back of where the #2 wire goes in right over to the top bolt(straight shot). Now im just hoping the replacement beck and arnley cap doesn't suck too..
Let me know if you find anything out
Nick

[discnick]

So i figured out my issue... My duralast distributor cap from autozone was grounding out the #2 spark wire... I reinstalled the cap without the plastic cover and to my surprise I could clearly see the lightning bolt jumping from the back of where the #2 wire goes in right over to the top bolt(straight shot). Now im just hoping the replacement beck and arnley cap doesn't suck too..
Let me know if you find anything out
Nick

[bimmerboy12]

I will work on the wires tonight. I KNOW its electrical.
Discnick are your wires new or used? I could rule out wires if I had the spares but I trashed those too.
A thing to think about, when I popped off my cap to peek inside (couldnt take all the way off due to shroud/fan) then replaced, the car REALLY idled like SHIT, stumbling pretty bad for about 3-5 seconds, then went back to the typical kinda shitty idle.
I hate to relay little experiences like this cause it could have been caused by anything, but Im getting desperate as it has been months now with this issue.

[discnick]

Went to autozone replaced it with new one of same brand... same problem... This is definitely a problem with the #2 spark... Im thinking since that wire is right up near the top on the cap its probably grounding out on the screw thats right above it... He ordered one of another brand that will be here in a few hours, so i'll be going back and trying that one. Try pulling your wires off the plug one by one enough you can hear it trying to jump the gap from the wire to the plug... let me know if you don't hear anything when you do it on the #2 wire... oh and i assume no responsibility if you get zapped.. :)
anyone know another reason why a single wire wouldn't be getting electricity? does the coil put out a pulse to the distributor or is it a steady flow? I could see if it pulses maybe it has something to do with whatever is controlling the pulse... but I dont know.. Try to do the wire thing asap
I'll let you know about the new cap
Nick

[bimmerboy12]

Sorry if this has already been brought up. Have you checked the engine harness plug? Notorious for getting filled with water and corroding. I found mine that way, with two of the wires broken causing similar problems to what you are experiencing.

My car ran great. I replaced all the parts, now idles like shit. The cap makes more sense...

[twothrees]

Sorry if this has already been brought up. Have you checked the engine harness plug? Notorious for getting filled with water and corroding. I found mine that way, with two of the wires broken causing similar problems to what you are experiencing.

[discnick]

rough idle - distributor cap

So I just tried something, and im fairly certain its my cap. I got it from auto zone(emergency situation, needed it right away). I pulled off each wire from the plug still in the head to listen for spark jumping from wire to plug and low and behold #2 isn't getting electricity.. Tried switching the #3 wire and #2 on the cap and on the plugs just to rule out bad wires and problem stayed at #2 no spark. Considering I've already changed the rotor to the old one and the only next logical thing would be distributor cap, I've got to see if they will replace/warranty it as I cant find my receipt :( I will let you know what I find, going to try to get this done quick as its very annoying driving my car at the moment. Just to clarify my symptoms too... cold start it has no miss, runs nice at idle and all through the range.. after about 2-3 minutes of running it develops a miss at idle which sounds rhythmic which makes me think it is isolated to a single cylinder. Going through the rpm range it seems to clean up at around 2k rpm and sometimes stays clean all the way to red line but I have also felt random hiccups in all different spots in the rpm's. Even the idle miss is not 100% consistent, seems to miss, hunt, idle nice, miss etc..
I will let you know
Nick

[bimmerboy12]

Unfortunately, I already trashed my cap. It was in really bad shape. I peeked in my new cap and I can see carbon tracing. Is this acceptable with only 500 miles on it?
When I unplug the O2 sensor it does nothing, but it shouldn't do anything at idle. When I unplug my CTS the idle goes from 650 rpm up to about 900, which naturally smooths it out a little.
discnick, that is encouraging that you have the same symptoms and have replaced items with no luck... good for me at least. Where did you get your cap? I got mine at Bavauto. Is it me or is Bavauto's stuff getting cheaper in quality?

do me a favor and try changing out your distributor cap to the old one... I just replaced my timing belt, plugs, dist cap and rotor. I drove the car about 300 miles and now its doing exact same thing as yours.. Changed plugs, same, changed distributor rotor, same.. I cant try my old dist cap cause i dont have it but thats what im thinking it is. the last cap on the car had electrical pitting on it when i replaced it, and the new one after the 300 miles has even worse pitting of the same sort, im thinking the tabs are too far from the rotor and not having good contact. I can hear a spark sound as if wires were bad and grounding out on something-- its not that though... like i said i think its the rotor too far from the tabs and that would make the same sound. Change it out and let me know.. thanks
Nick

They are not two prong plugs, they are single electrode Bosch Platinum Plus.

Ive heard of weird issues with the two prong plugs as well, but I just dont see it being that.
Does it just seem like it has a lobey idle? Like you've got a hot cam in it or something?

[discnick]

cap

do me a favor and try changing out your distributor cap to the old one... I just replaced my timing belt, plugs, dist cap and rotor. I drove the car about 300 miles and now its doing exact same thing as yours.. Changed plugs, same, changed distributor rotor, same.. I cant try my old dist cap cause i dont have it but thats what im thinking it is. the last cap on the car had electrical pitting on it when i replaced it, and the new one after the 300 miles has even worse pitting of the same sort, im thinking the tabs are too far from the rotor and not having good contact. I can hear a spark sound as if wires were bad and grounding out on something-- its not that though... like i said i think its the rotor too far from the tabs and that would make the same sound. Change it out and let me know.. thanks
Nick

[abepark]

have you swapped the connections on the CTS? If you unplug the O2 sensor anything change?

[bimmerboy12]

Does everyone concur I should go pick up some Bosch Supers and try it? Is that what everybody is using?

[bmwpower]

I assume you trashed the old plugs? I used Bosch Supers (copper), just don't know the exact ones, but I'm sure a lot of people run the same ones and can give us that info.

In fact, my new car in my sig is experiencing the same thing. The PO used Autolites, which I'm going to change soon. I have the new plugs in the garage, just don't remember what they are since I bought them several years ago for my last car and wrecked it before I could change them out again.

[bimmerboy12]

I dont know man. I think you're just overlooking something.

When you figure it out, you'll probably kick yourself.

I agree.