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ecu... working or not?

12-10-2009, 07:00 PM
so I have recently bought an ecu from a guy.. cause supposely my ecu is broken (idels up and down).....

with the new ecu... it calmed down a bit but the moment i turn on the ac/ heater, my car will die on me.

he says that my spark plugs wire are bad or something... is it the new ecu? it seems okay when i drive but i'm in a stop, the idle will fall and the engine stalls.

Sonic Eclipse
12-11-2009, 09:36 PM
My brothers 91 Laser does the same thing with the idle sometimes, we haven't changed the ECU yet but we suspect thats the problem.

As for your other problem with the car dying when you turn on the AC/heat, well thats kind of weird. I know when you replace the ECU, your suppose to match up the features that are on your car with the features on the new ECU (ie; 5spd, auto, turbo, PWR locks, PWR windows, PWR steering, etc.) or else some of your features will not work if the new ECU comes from a car without them. But I've never seen a DSM that didn't have AC/heat.

I'd say if you didn't have these problems before you put the new ECU in, then I would change it out. Put the old ECU back in to see if the problem continues, if it doesn't then you know its the ECU.

12-12-2009, 10:38 AM
I highly doubt your spark plug wires are causing this issue. May be a good idea to replace then if they have never been changed along with other maintanence that gets neglected.

Have you test the ISC yet? (idle speed control) If this is bad it could cause a bad idle and also when you turn the AC it puts more load on the motor and it needs more air/fuel to keep running at the same idle speed so if the ISC is not working properly it could also cause the car to die when the AC is turned on. That is where I would start looking.

Also do a boost leak test

12-12-2009, 06:38 PM
Also do a boost leak test

How do u perform one?

12-12-2009, 06:42 PM
How do u perform one?

google it.

Get a chiltons manual or a haynes manual to test the isc.

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