Emissions Problem
Thread Starter
Instructor
Joined: Jun 2003
Posts: 151
Likes: 1
From: Newark CA
Emissions Problem
I am having a bit of a problem passing the good ole' California smog inspection, and am looking for some help with ideas on what the problem could be. First a little history about the motor.
It is a LT based motor - 383 stroker, Lt4 AFR heads, Lt4 stock camshaft, Lt4 intake. It has about 15k on the rebuilt motor. It just barely passed smog a year and a half ago. I have 2 different PCMs the
1st was programmed by PCM for Less, the 2nd by Fastchip.
Using the 1st PCM the car failed with the NO number being too high, the CO & HC numbers were good.
Using the 2nd PCM the car failed with the CO number being way too high - actually a "gross polluter". The car was spewing black smoke out of the right side exhaust. The car started running poorly, so I pulled & replaced the right side spark plugs which 3 of 4 were full of carbon & smelled of gas. I also replaced the forward right side Oxygen sensor.
I would hope to not have to start replacing parts one at a time until I happen upon the problem.
Any help would be greatly appreciated.
It is a LT based motor - 383 stroker, Lt4 AFR heads, Lt4 stock camshaft, Lt4 intake. It has about 15k on the rebuilt motor. It just barely passed smog a year and a half ago. I have 2 different PCMs the
1st was programmed by PCM for Less, the 2nd by Fastchip.
Using the 1st PCM the car failed with the NO number being too high, the CO & HC numbers were good.
Using the 2nd PCM the car failed with the CO number being way too high - actually a "gross polluter". The car was spewing black smoke out of the right side exhaust. The car started running poorly, so I pulled & replaced the right side spark plugs which 3 of 4 were full of carbon & smelled of gas. I also replaced the forward right side Oxygen sensor.
I would hope to not have to start replacing parts one at a time until I happen upon the problem.
Any help would be greatly appreciated.
Former Vendor
Joined: Nov 2006
Posts: 2,482
Likes: 3
From: Carmichael ca
Sounds like the first one isn't allowing the EGR valve to work or advancing the timing too far, either could cause high NO. You may have to get a new chip burned.
What year is your car? If its OBDII, you can get software to tune it yourself.
What year is your car? If its OBDII, you can get software to tune it yourself.
Last edited by Paul Ruggeri; Oct 29, 2008 at 07:07 PM.
Thread Starter
Instructor
Joined: Jun 2003
Posts: 151
Likes: 1
From: Newark CA
Thanks
