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Posted

Hello, a friend of mine has a 89 Cutlass Supreme, and is having a bit of a problem passing emissions.

 

My question is this, is there a good way to diagnose the EVAP system? He's getting a code 45 (O2 sensor fail, rich) and we just ran his O2 on an oscilloscope, and the thing is almost constantly above 1V output, and spiked to 2+V a number of times. He just finished testing his injectors and they all read properly, and he just replaced his MAP sensor, so next target is the EVAP. Any help is appreciated. Thanks.

Posted
Hello, a friend of mine has a 89 Cutlass Supreme, and is having a bit of a problem passing emissions.

 

My question is this, is there a good way to diagnose the EVAP system? He's getting a code 45 (O2 sensor fail, rich) and we just ran his O2 on an oscilloscope, and the thing is almost constantly above 1V output, and spiked to 2+V a number of times. He just finished testing his injectors and they all read properly, and he just replaced his MAP sensor, so next target is the EVAP. Any help is appreciated. Thanks.

 

Theres your problem. The 02 voltage should constantly fluctuate, hardly every staying constant.

Posted

Hi, thanks for the welcome.

 

His O2 is brand new, probably less than 2 months old. Maybe it's been contaminated already, but that still means there is another problem somewhere. We're thinking if it isn't the EVAP, then the ECM is gone. Thanks.

Posted

If your cat is bad, it will cause early failure of the o2..... Something to check....

Posted

You should never see more than .9 volts from the O2 which is pretty rich. Sounds like your voltmeter won't read tenths of a volt. :( Try your meter on another car. Try your O2 on another car.

 

What failed? HC (PPM) I'll bet. Just went through that BS. If so it could be as simple as a vacuume leak on the MAP sensor or the fuel regulator.

 

Jud

Posted

Wierd, I posted a reply a few hours ago and it seems to have disappeared.

 

Anyhow, he replaced the ECM today and the car relearned its operating conditions. The exhaust odor was a lot better than before. Hopefully it was just that although he has a backup set of cylinder heads just in case.

 

A few things, he does have new cats. And new MAP, O2, ACT, vacuum lines, ECT, etc, etc. I think the only old part is this stupid ECM. The O2 readouts we got were actually from a digital oscilloscope, a guy I do some work for is a contractor that goes out and measures the fluctuations in giant industrial motors to see if they need maintenence. I highly doubt it was inaccurate. He failed both HC and CO (in my state it's both in grams/mile).

Posted

i just went for my emmisions test last wednesday and passed. i went in thinking i was going to fail so i took 1/4 tank of gas, and to bottles of Iso-heat, and then beat the hell outta the car on the way there. I thought i was going to fail cause two years ago, i barely passed, and my cat has gotten worse, and now rattles constantly. made it though. when i got there, it was so hot, when you gave it a little gas, it rattled so bad, i was supprised that i passed. He should also make sure he has a clean throttle body, iac, air filter, and the tire pressure is where it belongs.

 

nick

Posted

Grr, FAIL

 

HC : 0.8 std 1.76 read

CO : 15.0 std 21.2 read

 

Where exactly is the evaporative canister on these things? Thanks.

Posted

Im glad we dont have those emmisions test here where I live. Hell all they would have to do is look up at the ozone dissapearing above my cars as I drove by. :lol:

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