ECU Problems

[jakker91]

Driving back to Arizona today for my last year of college, get into Phx and my 1991 325i just gave up. Orginaly thought it was the fuel pump but local shop is telling me the ECU just got to hot and wont work anymore. Anyone have any previous problems with their ECU like this one or any advice?
Jack

[jlevie]

That is possible, but a failed CPS or a fuel system problem should be considered first.

[Rose E30]

I know that lemons guys will blow e30 ECUs by running at 5k plus rpm for long periods of time. What were you doing to it?

[Gregs///M]

Doubt it, those ECU's are grounded directly to the frame. It would be like placing a huge car sized heat sink on it.

It can be damaged from cracked solder joints or electrical wiring shorts.

[TobyB]

Likewise, while they DO give up occasionally, usually they stop working
because one (or more) of their inputs has stopped talking.

And revs don't wear ECU's out... vibrations might shake them to death, but
your average road car (or lemons car) is a chariot compared to serious road course
racing, and they haven't proven particularly fragile for that...

t

[Threehz]

What kind of symptoms you experiencing?

I know the Arizona heat gives my car problems. Not sure what it is yet... My new fuel pump will whine like crazy as my idle rises and drops and tries to steady out, and I'm not sure if the fuel pump whine is a symptom of the idling or the cause...

Anyhow, that problem only occurs if my car has been sitting in the sun for a while, and the hotter it is (outside temp & car from driving) the more intensified the problem is. I never considered the ECU but I'm sure a trip in the heat from CA to AZ could kill it.

[jakker91]

To Rose e30 I was driving from Los Angeles to Phoenix so 6 hour drive and was averaging 85-90mph. The Mechanic took out the ECU and put it in the "fridge" for about an hour then placed it back in the car and said it started up fine then died after about a minute.
When it failed i was going about 75mph on the freeway. I have noticed how rough the heat is on an older car but might have to send it home if they keep up. Don't want to do anymore damage.
Jakker91

[jlevie]

I know the Arizona heat gives my car problems. Not sure what it is yet... My new fuel pump will whine like crazy as my idle rises and drops and tries to steady out, and I'm not sure if the fuel pump whine is a symptom of the idling or the cause...

I'd bet on the whine from the pump being a symptom of the cause of the problem. Either the pump is having to work too hard or it is bad.

[nando]

I know that lemons guys will blow e30 ECUs by running at 5k plus rpm for long periods of time. What were you doing to it?

I'm pretty sure RPM has nothing to do with "blowing an ECU".

they're 20-25 years old, subject to vibration, moisture, and temperature extremes. some components like capacitors have a finite lifespan..

[Threehz]

It's definitely true that heat and electronics are worst enemies..

Now the mechanic said that he put it in and it worked for a minute then died? If the ECU is really dead why would it work for a minute? Usually when electronics overheat they die or become temporarily dead until the heat dissipates. A minute of running is definitely not enough to overheat it again.

What types of symptoms did the car exhibit when it died? And again when it died for the mechanic after a minute?

[bastianshaw]

ur gonna get raped lol

[Jaxx_]

what the fuck was the mechanic doing putting an ecu in the fridge? If the ECU is dead, I'm sure the moisture from this stunt is what did it in.

[nando]

I've saved data off many "dead" hard drives by putting them in the freezer, so they'll run just long enough to get files off them. never heard of doing that with an ECU, though..

[Rose E30]

Found the lemons source. I think I mis-remembered the bit about 5k rpm (it relates to floating valves) but they do have problems with going though ECUs at an alarming rate.

ross2004 wrote:
Not trying to make it bullet-proof, just trying to fix/address any glaring issues now vs. race day. We found this car with a blown headgasket on Craigslist for $500, and bought it without realizing e30's are not liked by many. Oh well, too far into it now... Sounds like electrical problems are the most prevalent- I think we have a solution for that.

One of the major electrical problems you'll face (ECM munching) is mainly due to running high duty cycles on the transistors. The heat dissipation design of the ECM is not sufficient for continuous high RPM duty. If you want to run over 5k RPM reliably you could consider designing a water-cooling setup for the ECM. That would be a the kind of totally ridiculous solution to a problem that is in the spirit of the event. Putting a megasquirt in there and trying to hide somewhere would not be in the spirit of the event.
Also remember if you are applying for a race that fills up you may not get in with an E30 vs something else. You aren't guaranteed a spot by just applying. This is where a great theme and the right attitude helps.

[pantelones]

I've saved data off many "dead" hard drives by putting them in the freezer

Hmm I used to do the same thing with my Nintendo games when they didn't work. They worked just about every time after doing it!