$500 in parts- now have stumbling issue

[bimmerboy12]

Have you tried to unplug the battery for 30 minutes and plug it back up? Doesnt the Motronic on your car adjust fuel rates on its own?

Did you put the CTS in the wrong spot? Mix the wires?
Have you checked the clearance on the throttle position sensor?

The timing belt was put on right, I rotated and verified the markings were lining up correctly per the Bentley manual. It is pretty obvious if it is a tooth off. I swapped the old CTS back in for the old with no change. I bench tested the old and the new CTS per the Bentley manual and they checked out fine. The wires are correct as they are numbered (from Bavauto). The plugs I am using are Bosch Platinums (not +2 or +4). Is this OK or should I have used standard Bosch plugs?
I did not check the clearance on the TPS, I don't know why it would have changed as I did not touch it throughout the procedure. Bentley manual doesn't say much about the TPS when I look it up.
I will try unhooking the battery for more than 30 minutes. Hell, I will try anything at this point.

[bmwpower]

The timing belt was put on right, I rotated and verified the markings were lining up correctly per the Bentley manual. It is pretty obvious if it is a tooth off. I swapped the old CTS back in for the old with no change. I bench tested the old and the new CTS per the Bentley manual and they checked out fine. The wires are correct as they are numbered (from Bavauto). The plugs I am using are Bosch Platinums (not +2 or +4). Is this OK or should I have used standard Bosch plugs?
I did not check the clearance on the TPS, I don't know why it would have changed as I did not touch it throughout the procedure. Bentley manual doesn't say much about the TPS when I look it up.
I will try unhooking the battery for more than 30 minutes. Hell, I will try anything at this point.

My money is on the plugs. Like I said, I had problems before using the plugs you're using.

[scabzzzz]

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?

[twright]

I think you have a vacuum leak. And don't forget that an oil leak on this engine (valve cover, dip stick, etc.) is also a vacuum leak.

[bimmerboy12]

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.

[scabzzzz]

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

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

[bimmerboy12]

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

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

I agree.

[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]

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

[abepark]

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

[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

[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]

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

[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.

[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...