Emissions test and computer woes...

[mcclja]

I took my '93 Corolla (1.8, 4spd auto) in to have the check engine light diagnosed. After going through the car for a good part of a day, the mechanic determined that there was nothing wrong. The computer is showing a code related to the EGR valve, but my mechanic said the EGR valve was fine. He determined that the computer was simply giving off a false signal. But the problem is that my car will not pass a smog check with the danged light on and a replacement computer will cost over $700.

Has anybody else encountered this? Any possible solutions?

[toyotaspeed90]

go to a junkyard for a new ecu.... or watch ebay....

you could possibly disconnect the battery then reconnect it to reset the ecu.... slight chance that might get ya to pass.....

[mcclja]

I've tried the disconnect-reconnect battery technique without any luck. My mechanic also cleaned the terminals for the ecu which seemed to keep the light off for about half a day.

I'll probably end up making a run to the local junkyards, although I've noticed a lack of Corollas in those places in the past.

[NDR008]

can't you just disconnect the wire of the lamp for now?

[OEMonkey]

Has anybody else encountered this? Any possible solutions?

ya.
pull the code, confirm its a prob. with the egr circuit. checking the egr itself only tells you the egr valve is fine, doesnt tell you anything about the circuit or how well and how much it recirculates when it's enabled. if its a prob with the sensor, then you either have a short or open so check the sensor, its most likely a thermistor and has resistance values for different temps. at worse, youre gonna have to change the sensor. if its a mechanical prob., such as low flow because of carbon buildup blocking egr flow, then just take off the egr valve and clean the passage ways and put it back with a new gasket of course.
if you disconnect the lamp for the cel, it doesnt solve your egr prob. and since your from cali., you will fail your test for NOx.

my mechanic said the EGR valve was fine. He determined that the computer was simply giving off a false signal

you need a new mechanic. actually, dont go to mechanic. go to a technician. when you need a clutch job, then you can go to a mechanic.

[OEMonkey]

o ya, when you go get your smog test make sure you tell the tech. that you want a pre-test first. this way if you fail it wont count against you. and if you fail, you'll still get a copy of your VIR. and thats a pretty good diagnostic baseline before starting on your repairs.