DKCAIMS
TYF Newbie
Just an FYI in case anyone else here might be having problems passing the nox
portion of emissions tests in your area.
My dad bought this 2000 Yukon a few years ago from TYF member "TheFuzz".
Let me just say that JB is a stand up guy and we would not hesitate buying another vehicle from him.
Having said that...
We always had a tough time passing the nox portion of the emissions test.
The limits here for this vehicle is 2.00 for nox.
My dad was so tired of dealing with this problem every time it was due for an emissions test.
When it did pass, it was just barely. Usually 1.75 to 1.96, but that was after doing numerous things to it. Seafoam, clean EGR tubes, clean MAF, check this, check that !
A pain in the ass to say the least.
The Yukon had an AEM cold air intake and Black Bear tuned PCM, otherwise stock.
I wanted to eliminate the possibility of those things being the cause of the problem before I started throwing money at it.
I found a tahoe owner who had a stock air intake. He came over to the house and a few minutes later, he drove away with the AEM in his tahoe and the stock setup was installed in the yukon.
Time for an emissions test...
Test #1 = FAIL ! tested at 2.6948 and the limit is 2.00
Onto the PCM...
I had trouble finding someone local to flash it back to oem specs, but I eventually found John Spears of SpearTech in Indiana.
http://www.speartech.com
John was a GM electrical systems engineer for 23 years with a good portion of that time spent in engine controls and ignition systems development.
So I sent him the PCM and a few days later I received back, flashed back to oem VIN specs, plus he made an adjustment for LT285 tires.
Test #2 = PASS ! Tested at 0.3945.
The ONLY thing done to the yukon between the 1st and 2nd test was having the PCM flashed back to stock and filling up with 85 octane regular fuel.
I'm not saying that all aftermarket PCM tunes will result in failed NOX (many places don't test for nox anyway), but in my case, it was clearly the cause of all the prior failed tests and headaches.
Just thought this might be useful to anyone else who is having similar problems now or in the future.
portion of emissions tests in your area.
My dad bought this 2000 Yukon a few years ago from TYF member "TheFuzz".
Let me just say that JB is a stand up guy and we would not hesitate buying another vehicle from him.
Having said that...
We always had a tough time passing the nox portion of the emissions test.
The limits here for this vehicle is 2.00 for nox.
My dad was so tired of dealing with this problem every time it was due for an emissions test.
When it did pass, it was just barely. Usually 1.75 to 1.96, but that was after doing numerous things to it. Seafoam, clean EGR tubes, clean MAF, check this, check that !
A pain in the ass to say the least.
The Yukon had an AEM cold air intake and Black Bear tuned PCM, otherwise stock.
I wanted to eliminate the possibility of those things being the cause of the problem before I started throwing money at it.
I found a tahoe owner who had a stock air intake. He came over to the house and a few minutes later, he drove away with the AEM in his tahoe and the stock setup was installed in the yukon.
Time for an emissions test...
Test #1 = FAIL ! tested at 2.6948 and the limit is 2.00
Onto the PCM...
I had trouble finding someone local to flash it back to oem specs, but I eventually found John Spears of SpearTech in Indiana.
http://www.speartech.com
John was a GM electrical systems engineer for 23 years with a good portion of that time spent in engine controls and ignition systems development.
So I sent him the PCM and a few days later I received back, flashed back to oem VIN specs, plus he made an adjustment for LT285 tires.
Test #2 = PASS ! Tested at 0.3945.
The ONLY thing done to the yukon between the 1st and 2nd test was having the PCM flashed back to stock and filling up with 85 octane regular fuel.
I'm not saying that all aftermarket PCM tunes will result in failed NOX (many places don't test for nox anyway), but in my case, it was clearly the cause of all the prior failed tests and headaches.
Just thought this might be useful to anyone else who is having similar problems now or in the future.
