$500 in parts- now have stumbling issue

[dj01540i6sp]

Suggestion - I see a new Valve cover Gasket on your list did you replace the 4 small rubber arrow head pieces. Is a very small vacuum leak possible to cause this just at Idle?

Good Luck
Keep your hair

[bimmerboy12]

Suggestion - I see a new Valve cover Gasket on your list did you replace the 4 small rubber arrow head pieces. Is a very small vacuum leak possible to cause this just at Idle?

Good Luck
Keep your hair

No Check Engine Light. Car stumbles when cold and when hot, but differently.

Yep, replaced the four "D" shaped rubber pieces, old ones were hard as a rock.

I will try pulling the booster hose to see if the car dies, but this was in an area that was untouched and all lines were checked for vacuum leaks.

Also, I put this cap back on without the black cover, and there was no arcing anywhere as was seen on others caps on this thread. There were no carbon tracks inside the cap.

I am now thinking about my valve adjustment. All the valves were right on, could they have moved afterwards causing this issue?

hair is in grave danger.

[Mitchel]

Pull out the brake booster. If it dies, chances are there's a vacuum leak elseware. Easy way to rule it out man.

[bimmerboy12]

Pull out the brake booster. If it dies, chances are there's a vacuum leak elseware. Easy way to rule it out man.

OK, pulled the brake booster vacuum line. Started sucking air like a bitch and idled horribly but did not die. Plugged it back in and resumed to normal shitty idle.
I have now done everything you guys have suggested. Please don't tell me its time to take it in to the stealer...

[SpecM]

I don't see how mis adjusted valves could cause this

I would be concerned about that cap/rotor, that's more scoring than I've seen on 20k units, much less 1k ones.

[xwill112x]

+1 with cap and rotor

[nomis3613]

my 2 cents

OK, pulled the brake booster vacuum line. Started sucking air like a bitch and idled horribly but did not die. Plugged it back in and resumed to normal shitty idle.
I have now done everything you guys have suggested. Please don't tell me its time to take it in to the stealer...

Sorry to hear you're still having problems. I know how much it sucks, I've been through a very similar saga. Got a mechanic to do timing belt (just like you did yourself), valve gaps and mixture adjustment and from then on it intermittently idled like a pig and throttle response was terrible. That was over a year ago, and various mechanics could never find the problem. But last weekend I got it back from a fine-toothed comb job at the mechanic...and...IT'S FIXED!!!

So hang in there dude, with patience and a logical approach you will get there in the end. My problems (check your PMs) turned out unrelated to original work, just coincidence that the problems started then, or perhaps it just upset the delicate mystical balance of an engine that was hanging in there despite its problems. And it will be worth it in the end, because I've rediscovered how wonderful these cars are to drive when they're running properly.

Enough pep talk, here's my conspiracy theories:
1 The Bosch ECU has a set warm-up cycle where it runs a pre-programmed sequence. Only after a certain time does it start listening to its sensors. If it runs fine when cold, then it points towards a faulty input (or input processing in the ECU). You said you changed the "sending" CTS, sorry could you confirm this is the one to the ECU, not the dash?

2 I wouldn't write off vacuum leaks just yet. Perhaps others can help here, but will stethoscope testing pick these up? FWIW My mechanic did a smoke test and found some leaks I wasn't aware of.

3 I would also check the rotor/cap. Might not be the main cause, but possibly a contributing factor.

4 Sorry if you've mentioned this, but have you tried your old plug leads?

5 Go back to basics with some testing while it is running bad. Sure this stuff will seem irrelevant considering what you changed to cause the problem but it'll help you narrow down the cause. You might need to go to a pro cause they have the tools, but if go to an independant not a dealer and just ask for a specific test then you shouldn't get bent over backwards too much! Checklist:
Fuel pressure?
Spark trace on oscilloscope?
Mixtures rich or lean?
Fault codes?

Hope ya get sorted soon.:drink:

Simon

[bimmerboy12]

ok, so now I am really pissed off. I just had the car in the garage to check that booster vacuum hose, and I reset my service indicator, and had the car on the "accessory" position for an hour to reset my radio (wrong code too many times). THATS IT. Now I try to start it and nothing happens when i turn the key! full 12 volts. NOTHING! I am so fed up with this! I feel guilty when I say I was browsing for E46's today...

[bmwpower]

Geez. You can't catch a break.

You sure it's 12v at the battery?? Not even a crank??

[bimmerboy12]

Geez. You can't catch a break.

You sure it's 12v at the battery?? Not even a crank??

NO NOTHING. as if there wasn't even a starter there.
Is there a fusible link on this car I can check?

[bmwpower]

NO NOTHING. as if there wasn't even a starter there.
Is there a fusible link on this car I can check?

I *believe* there is a fusable link but never saw it. Definitely check the fuses upfront. Not sure why they would blow like that, but I'm wondering if this is getting you closer to the read problem.

[E30Eric]

Often times the injector harness plug under the IM gets corroded.(coolant temp wires are also a part of this harness) Especially the coolant temp sensor prongs. I am heavily leaning towards that. So depending on how you are testing the sensor, if you just measure the resistance across the sensor that will not help you if one of the wires for the sensor is corroded in the harness.

[bimmerboy12]

Often times the injector harness plug under the IM gets corroded.(coolant temp wires are also a part of this harness) Especially the coolant temp sensor prongs. I am heavily leaning towards that. So depending on how you are testing the sensor, if you just measure the resistance across the sensor that will not help you if one of the wires for the sensor is corroded in the harness.

OK, the car not starting was a low battery symptom, apparently having the key in the accessory position for an hour drained it enough that it would not turn over, even though it measured 12 volts??? Charged it up and its fine. That crisis averted hopefully.

I cleaned all the corrosion out of the circular harness beneath the IM, I am pretty sure that is OK. I know the coolant temp sensor is doing something, because when I unplug it while running the engine will idle high, around 1200 rpms or so. Plug it back in and it drops to around 700-800, but still stumbling.

[bmwpower]

So it stumbles at all engine temps, right?

Does it stumble when you remove the harness from the temp sender?

Measure the resistance at the engine temp sender prongs.

[bimmerboy12]

So it stumbles at all engine temps, right?

Does it stumble when you remove the harness from the temp sender?

Measure the resistance at the engine temp sender prongs.

Yes, it stumbles at all temperatures, sometimes it is worse that other times randomly. Sometimes when I start it cold it will idle so rhythmically that it will almost die when I put it in gear.
If I remember correctly, it will not stumble when you remove the CTS harness, because the idle goes up high enough to smooth it out (Im assuming). I will try again tonight and also measure the resistance across the prongs. Look for another post in 6 hrs.
Thanks again everybody.
Brian