Rusty-one-1

I all I am new to this forum and just bought my first corvette, a 1980. I live in California and am having a terrible time getting this thing to pass smog. I read here somewhere that this car should not have an ECM, but the smog tech is telling me that it does and it is not working, I have searched and can not find the ECM. The carb does seems to have all these electrical connections on it and an 02 sensor, all that stuff. Any help would be greatly appreciated.

Rusty-one-1

Wow no one with even a clue, this is gonna be more difficult than I thought

Smadoo

Sometimes it takes some time to get an answer. Just relax.


1980 was the last year that corvettes did not have any computers on them. 1981 had a computer controlled carb, but not in 1980. I would check with a different mechanic for inspection.

Edit: Never mind, California 305 engines had the computer controlled carbs.

But if you're failing the emissions tests then there could be other issues with your emissions system. ie missing cat, AIR... Commonly removed by previous owners to try to free up some power.

qwank

The California only 305L Engines in 1980 had computer controlled carbs.

Rusty-one-1

ya its a California car that some one put a 350 in with all the emission stuff on it but the ecu seems dead or? I dont know but the smog test did not go well

CA-Legal-Vette

Don't panic quite yet. Let's start at the beginning. What does and doesn't it do?

Does the check engine light stay on all the time?

When you say " did not go well" besides not passing, what do you mean?

Does it still have the catalytic converter?

Last question, where in CA are you located?

terry82

can you take a pic of the carb?that will tell us what you have .have you looked next to the batery for a ecu?the ecu may not be working because there are things that are not hooked up.if you dont have the right carb that may be most of your problem.

Yellow1980

If you bought the car in California the seller is responsible for the smog. It's not legal for them to sell it without it. See link http://dmv.ca.gov/vr/smogfaq.htm#BM2537

If you bought the car outside California the law does not apply.

1980 California Corvettes where built with a 305 and had an ECM, but not the 49 state 1980's with the 350. How far off are you on the smog numbers?

spedaleden

In 1981 the ECM was mounted in the battery compartment. Try there!

Rusty-one-1

Ok it has the catalytic converter, I think the electrical system has failed so the carb has defaulted to full rich. The Check engine light is not working because some one removed the bulb from the dash (I just discovered this) I assume because it was on all the time but dont know. I have not tried another bulb yet. The air pump diverter valve is missing its electrical connection (broke off?? says the smog tech and i have searched as far as i can think including Ebay for a replacement with no luck so far. I am in Northern California Chico, South of redding North Sacramento

Rusty-one-1

I did find it there thank you, I have a bad problem with ground in this car, and was hoping maby the ECM had lost its ground somewhere too but I ground the terminal it says to in my nearly worthless Chilton book and no change it seems

Rusty-one-1

Thank you I bought the car from a guy in Nevada, it is originally a California car tho.

CA-Legal-Vette

I suppose the best place to start is by getting a bulb for the check engine light. We need to figure out if the computer is working. There is a built in diagnostic but you'll need the light to read any codes.

Parts for the diverted valve can be tough to find. Many people remove and toss them. I don't think any of the parts houses make them.

Rusty-one-1

ok a bulb will be no problem, the diverter valve is defiantly bugging me cuz like u said i cannot just buy it from any parts house. I can get a brand new smog pump any day I want but this part seems impossible, I was hoping junk yard but??? as far as reading codes is there a port to plug something into? some kind of reader? I thought this would have been way too old for something like that but I am new to this Thanks again for all the help I will get that bulb asap

Rusty-one-1

Also as far as the computer possible being dead, I have found just one for sale online and almost feel panicked to just buy it, he says its used from a running car and wants 100 bucks for it, can they be this rare to find?

CA-Legal-Vette

You don"t need a code reader. There is a port under the ashtray. You put a jumper wire across two of the terminals, turn on the ignition without startng the motor and then count flashes on the engine light.

$100 is pretty steep for a computer. Lots of people remove theirs. Not an option for you in CA though.

Rusty-one-1

Ok gonna try a few pics hope this works,,,




My car




The Carb







The diverter valve smog tech says is broken

Rusty-one-1

Ok good to know thats a bit too much to pay and u say if I get me CEL working I can tell if the computer is dead or not,, no need to throw parts at it i suppose

gbvette62

On the 80 Corvette, coming off the terminals that attach the wire harness to the ECM, is a black and white test connector wire. If you ground this diagnostic connector, the check engine light will flash a trouble code, if there is one present.

If everything is normal when the check is performed, code 12 will flash. Code 12 is flashed in the form of one flash, a short pause, and then two quick flashes. Trouble codes will flash in the same manor. A 34 trouble code will flash 3 times quickly, pause and then flash 4 times, a 51 code would be 5 flashes, then a pause followed by a single flash, and so on.

Only California Corvettes had the computor in 1980. Federal emission Corvettes didn't get the computor until the following year, 1981.

There were only 3,221 CA emission Corvettes sold in 1980. All 1980 CA Corvettes were 305's.

With only 3,221 CA emission 1980 Corvettes originally produced, the 80 ECM is pretty rare. The ECM's used in 81 and 82, are each different.

gbvette62

This is only true of 1981 and 82 Corvettes. The 80 is tested in the rear compartment, off a terminal in the wiring harness, at the ECM itself.