Failed Emission's Test
Racer
Joined: Jul 2002
Posts: 401
Likes: 1
From: Aptos CA
Re: Failed Emission's Test (imaflip1356)
Wow, this is an open question. You may have mechanical problems not related to the ECM. If you have done a complete tune-up on the car, then post this in Tech-performance to see what other people think you should check.
Thread Starter
4th Gear
Joined: Aug 2003
Posts: 4
Likes: 0
From: Portland OR
Re: Failed Emission's Test (Skippy Stone)
Thanks for the reply Skippy Stone.
The car sit's in the garage all winter and gremlins must come out and do their job since it was running great before storing it for winter. I will do a tuneup and see how it goes.
The car sit's in the garage all winter and gremlins must come out and do their job since it was running great before storing it for winter. I will do a tuneup and see how it goes.
Thread Starter
4th Gear
Joined: Aug 2003
Posts: 4
Likes: 0
From: Portland OR
Re: Failed Emission's Test (Skippy Stone)
I've changed the plugs, they all look at least close to normal except for one that was badly fouled up, no wonder it also ran rough. I hooked up my AutoXray and didn't find any trouble codes. It indicated a very low voltage on the O2, 17 mV. I believe that does mean running very lean or too much oxygen in exhaust. I didn't see any values for the MAF and the MAT indicates -40. Does the ALDL provide this info or only OBD2 has this provision.
Could this also mean some injectors are not working porperly?
Thanks for all the pointers.
Could this also mean some injectors are not working porperly?
Thanks for all the pointers.
Racer
Joined: Jul 2002
Posts: 401
Likes: 1
From: Aptos CA
Re: Failed Emission's Test (imaflip1356)
I've changed the plugs, they all look at least close to normal except for one that was badly fouled up, no wonder it also ran rough. I hooked up my AutoXray and didn't find any trouble codes. It indicated a very low voltage on the O2, 17 mV. I believe that does mean running very lean or too much oxygen in exhaust. I didn't see any values for the MAF and the MAT indicates -40. Does the ALDL provide this info or only OBD2 has this provision.
Could this also mean some injectors are not working porperly?
Thanks for all the pointers.
Could this also mean some injectors are not working porperly?
Thanks for all the pointers.
Instructor
Joined: Oct 2002
Posts: 135
Likes: 0
From: Pitman NJ
Re: Failed Emission's Test (imaflip1356)
I'll be honest and tell you I'm no expert but I tried to pass inspection and failed with NOx off the chart. That's because I was using gutted Cats. With normal Cats passed with flying colors. Maybe your Cats are bad or O2 sensors need replacing. Good luck.
6th Gear
Joined: Apr 2004
Posts: 6
Likes: 0
From: aurora il
Re: Failed Emission's Test (imaflip1356)
NOx is heat and GM used egr valves to control NOx and also camshaft over lap.
Make sure your egr system is working,also if you run higher octane fuel it will have a cooling effect and lower the NOx output.
Make sure your egr system is working,also if you run higher octane fuel it will have a cooling effect and lower the NOx output.
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Melting Slicks
Joined: Feb 2004
Posts: 3,055
Likes: 0
From: Sarcasm. Just one of the many services I offer.
Re: Failed Emission's Test (imaflip1356)
Try this. Run the car until the tank is almost empty. Right before the test pour a bottle of rubbing alchol in your tank. It always seems to work for me...matter of fact I did it a week ago on my 86.
