Hi,

I did bought an 91's Park Avenue, and with it some problems. I was by the Germany Test station, they check the cars if they good to drive on our street (Its named TÜV).

On emission test, the car failed, the gas mix was to rich, I hope you know what I mean. The CO Value is 0.600 must be 0.300
So I drive home and read trouble codes, and get this:

31 cam position sensor fault
65 oxygen sensor right side rich exhaust indicated / EGR flow check
68 a/c compressor relay circuit failure



So did code 65 mean the oxygen sensor must replace?

I must know where I start to search for the failed emission test.
Thx.

How old is your oxygen sensor?

I think its the first one, I bought the Car on Friday.

DTC 31 is not for the cam position sensor, that would be DTC 41. Check that again! If in fact you find DTC 41, you could have a bad cam position sensor, or broken/missing magnet in the cam gear. This problem will cause the injectors to fire out of time with the valve opening; therefore, the 02 sensor may read rich. In addition, you may also have an EGR restriction which means the EGR needs cleaning, or replacement.

Where did I find the EGR Valve?

Oddly enough, not all 91 base models seem to have an EGR valve.

So whats now?

It have an new Air Flow Sensor, and the Trouble codes are correct, minimum the number, i did find diffrents text for troublecodes.

So whats now?

It have an new Air Flow Sensor, and the Trouble codes are correct, minimum the number, i did find diffrents text for troublecodes.Please clarify your last post, we do not understand what you are trying to say! :rolleyes:

The car have a new MAF Sensor.
I found different interpretation

Page 1 (http://www.gmtuners.com/OBD1_DTC.htm)

or

Page 2 (http://www.troublecodes.net/GM/91_38L.shtml)

The Numbers of trouble codes are the same, but have different text...

Thanks, you should go by what is on: Page 2 (http://www.troublecodes.net/GM/91_38L.shtml)


See Page 1 (NOTE: Some codes not supported on all models, consult your specific vehicle's service manual for the correct trouble code list and description for your application.)

thx, but i didnt have any problems with cruise control, it works perfectly, I have problem with rich mixture...

Once again, please verify the code # 31. Are you sure that it is not # 41??

So its dark here, but I found the 2 right holes to read trouble code;)

Its 31, 65 and 68

I ordered a new o2 Sensor and new camshaft sensor and hope that the values will be better. Or did anybody have an better idea? Or another?

As I understand it, your cam sensor isn't the problem so replacing it would not affect the CO. The 65 & 68 codes also seem to have no influence on the CO. (?)
The life of a oxygen sensor is something like 40,000-80,000 km depending on factors such as the brand. Since it is unknown when it was last replaced, it would be a good idea to replace it. But it didn't set a code specific to the oxygen sensor...

I would think of a fouled catalytic converter. A vacuum leak or weak ignition components could also cause a high CO reading.

Typical Failure for Excessive CO

Possible causes of excessive HC include:


Faulty oxygen sensor(s).
Incorrect ignition/injection timing.
Faulty mass air flow sensor.
Faulty fuel pressure.
Faulty PCV valve.
Dirty fuel injection.


Catalytic converters do not cause high emissions. Rather they attempt to reduce excessive emissions from the engine. Engine component failures should be addressed before the converter is replaced to prevent voiding the converter warranty.

Need quick help, when I plug in the battery after I replaced all stuff, the car alarm turn on how get it quick off? Didnt have remote...

All Codes gone... Tomorrow I make a new Emission Test...

Need quick help, when I plug in the battery after I replaced all stuff, the car alarm turn on how get it quick off? Didnt have remote...Sounds like you sorted it out, but for others who may read this thread, just use the key to open the door in order to disable the alarm. :smooch:

It was a cheap aftermarket alarm system, I pull out the black box and now its all fine.
But where I seen the cables I could kill the preowner. So I have alot to do to make all cables original.

Wahhh test failed...
The o2 sensor did the right stuff, and regulate the mixture, but the sensor from the testingmachine read again rich mixture.
Can the catalyst converter been fault and didnt filter the co values?

Yes, but take Hotz' advice http://www.automotiveforums.com/vbulletin/showpost.php?p=6039525&postcount=15
and check the simple stuff first.

Emission test pass, it was the catalyst converter, the converter was complete empty...

Good, how did you find out ?

I put the old catalyst converter off and look in the converter. There was nothing in. So now im happy to register the car.

Aren't they supposed to be welded to the exhaust on the PA? At least Haynes states this

Yeah it was welded but I separated it. I ordered before this action an new one.