<FONT face="Arial, Helvetica, sans-serif"><IMG src=smileys/smiley7.gif border="0"> This old man needs some serious help with my '94 2.0 gs. I took my car thru the car wash and while I was waiting for them to dry it off I smelled electrical parts melting down inside the car. I had just recently installed a used idle speed control motor and car was running great until car wash. When I got home idle was a little erratic but other than that it seemed to run okay. Later that night engine would not idle at all. I looked into what might have burned out and it turned out I had somehow smoked my ECU, and now also ISC motor no longer checked out okay on resistance checks. So, I bought a rebuilt ECU and another used ISC motor,installed them both,and everything was great for about ten miles. When I pulled into garage and let the car idle for about five minutes, engine slowed down for a second and almost died, so I checked the ECU computer and smoke was coming out of it, OUCH !!! Pulled out ISC motor again, now that one is crap too.So, now I have three junk ISC motors, and two smoked ECUs. Anyone have any ideas ??? I don't think it's a coincidence that first computer smoked after car wash, I think something got wet and shorted out and whatever it is it's costing me big time. Any ideas welcome, Randy</FONT></P>

 

I definitely think the car-wash had something to do with it....but it's pretty much impossible for water to get near the ecu. Also, the isc wouldn't be affected by water that much either. Maybe water vapor??? Check all your elec. lines leading to the isc and see if they have any condesation on them or anything. Or maybe the connector plug. That is a hard problem to diagnose.

 

<IMG src=smileys/smiley19.gif border="0"> Thanks for the input SpyderGS. I will continue to check everything. Last night I pulled the coil assembly and power transistor module and checked them out according to service manual. Today, i'm sending both computers back to rebuilder for analysis. I'm also sending three ISCs to rebuilder for a rebuild. Computer rebuilders should be able to narrow down my problem by evaluating what circuit keeps burning up. Thanks, Randy

 

So you have the 2.4l dohc 4g64 engine, right? I remember reading somewhere that they'renot the greatest engine to work with. I think i read on TGC that they were vastly different in electronics to thesohc 4g64 and 4g63, disregarding the ignition. Maybe you have been using the wrong isc??? But since you are doing you're own work, i know you wouldn't overlook something like that. I personally always have a group of dsmer's help install stuff on my car with me. To tell you the truth,I know i'm not even competent enough to work with the ecu that much. If i smelled smoke, i start running.<IMG src=smileys/smiley5.gif border="0">

 

<IMG src=smileys/smiley19.gif border="0">It's got the 2.0 liter non-turbo 4g63 engine. I'm starting to think it didn't have anything to do with the car wash. I think it has more to do with an extended amount of idle time. Both computers burned up after about five minutes of idling. Also, both ISC's showed at least one bad coil on resistance checks after ECUs burned up. I talked to a electrical technician friend tonight and he said you can burn up a power supply (in this case the ECU) if the stepper (ISC) motor is defective. I guess i'd like to know if anyone else has experienced ECU problems after an ISC motor goes bad. I sent out both computers today to rebuilder for evaluation, should know more by the end of the week, Randy

 

<IMG src=smileys/smiley16.gif border="0">My car is now running perfectly.I found out you can smoke an ECU by installing a bad ISC motor.The two ISCs that I had previously both showed one bad coil with only 1 ohm of resistance,which means they had a dead short,as apposed to an open short.Since there is no electrical load at ISC coil ,current goes full blast right to ground thru the ECU transistors, burning them up.The transistor switches the ground connection on and off as told by the computer.It's like removing a lightbulb from a simple electrical circuit and just hooking the two wires together,you've removed the load and now either the wires burn up or you burn up the power supply.So anyway, I tried to be cheap and bought two USED ISCs from some a**hole on e-bay to save money and he sold me crap.I bought a rebuilt ISC with a warranty and a guarranteed used ECU and now all is right with the world.In closing,NEVER install a ISC that hasn't been fully tested out or it could cost you big bucks.