Car won't idle - did I damage my ECU?

[jsubbi]

I was pulling some fuses trying to troubleshoot a problem and when I tried to restart the car, the car will not idle--it just stalls. I haven't had any problems with my idle control valve to date. Is it possible that I pulled a fuse to the ECU and damaged it? I know, I probably should have disconnected the battery first.

There are no CEL indications. The car will run if I keep the throttle plate open. I tried to get to the ICV connector to test the ECU signal, but I haven't been able to access it--it's burried under the manifold.

Help?

[jsubbi]

I disconnected the battery hoping it might "reset" the ECU and then restarted it. It will now idle, but just barely (below 500 rpm?)

Is this because the ECU need time to recalibrate the idle speed? Or has the ICV decided to stick all of the sudden?

It's an '98 with 90k miles.

[jsubbi]

We'll, oddly the problem seems to have spontaneously resolved itself. I was driving the car over to Chris at Bullet Motorsport in Santa Ana, CA, (not to be confused with Bullet Performance in Costa Mesa) and on the way, the idle speed returned! Go figure.

I had Chris run diagnostics anyway and he found a fault code for the throttle position sensor, so that may have been the cause. Looks like an easy R&R.

It was my first time over at Bullet Motorsport and they seem like really good guys. It's always nice to find another good independent nearby.

[95DayVI]

I had imagined tho it would be hard to "break" something that wasn't already nearing a breaking point. It was probably just timing, and not anything you did specifically.

Supposedly the ICV can be cleaned and replaced._______
Silicone intake boot
Silicone rad hoses
EMP Waterpump
PWR Radiator
Eyeball Arm CA mounts
Sunbelt CAMS w chip for 24# injectors, Euro MAF, Conforti/ITG CAI
96+ exhaust manifolds
accessory UDPs
M roadster lever
Euro fLoAtErS
GC RTAB shims, RSMs, T/S Coilover with Koni DA f/SA R & 450#f/550#r Eibach ERS
All done in my garage

[jsubbi]

I think I may have solved the intermittent starting issue (my original problem). When Chris at Bullet was running diagnostics, he also found an ignition key ID error (where the EWS/ECU thinks the key doesn't match the car).

I later spoke to Leigh at the Irvine BMW parts counter about what he thought the issue was, and he thinks the chip in the key is failing and the key need to be replaced. He said they sell way more keys that ignition switches.

I was able to test this theory this afternoon. Once again, it wouldn't start. I grabbed my other key and it started right up. I'm going test it a few more times just to be sure.

The best part is a new key is under $100 and I don't have to tear apart the car. :-)

[95DayVI]

_______
Silicone intake boot
Silicone rad hoses
EMP Waterpump
PWR Radiator
Eyeball Arm CA mounts
Sunbelt CAMS w chip for 24# injectors, Euro MAF, Conforti/ITG CAI
96+ exhaust manifolds
accessory UDPs
M roadster lever
Euro fLoAtErS
GC RTAB shims, RSMs, T/S Coilover with Koni DA f/SA R & 450#f/550#r Eibach ERS
All done in my garage

[jsubbi]

[jsubbi]

I had the start problem several more times, but my "bad key" theory didn't hold up--my second key wouldn't start the car. I knew the problem was heat related, and based on the interior cabin temp, so I sprayed some cold compressed air (using a can of Dust Off) onto the ignition ring antenna (sits around the key hole and reads the chip in the key). Sure enough, the car started right up.

I kept the air can in the car to see if I could repeat the fix, and it worked successfully several more times, so I replaced the antenna. The best news is that it was only $40, even less than a new key!

John