Odd Years Bring Tears…

2011. Odd year. By odd I don’t mean strange, I mean it’s not even. Every odd year I need to get my emissions & inspection done for the state of Utah (my car is a 2007 model). No sweat, right? Ha ha…ha…

Safety inspections are no problem. Everything on my car is in tip top shape and I even have legal tinting. I will confess that I have legal tinting now because I had to rip it off two years ago for the safety test. But I digress… It’s the emissions that kill me. If you know anything about OBDII emissions testing you’ll feel for me shortly.

Emissions testing used to be done by literally measuring the emissions output from your car. However, newer cars can actually monitor their own emissions. When you go for an emissions test in Utah they just plug a computer into your OBDII port (usually located under your steering column) to see if your car passes or not. The car has a series of onboard emissions tests that it runs while you drive (checking the O2 sensor, fuel system, catalyst, misfire monitor, etc- it varies from car to car).  If your car successfully runs the tests (you can have one “incomplete” test in Utah) and your MIL (Malfunction Indicator Lamp, also called the “check engine light”) is off then you’ll pass your emissions inspection. If your car doesn’t run the tests or fails them then you have a potential problem. And a quick side note- disconnecting your battery will erase your test results! Don’t change or disconnect your battery right before an emissions test.

My emissions test was due at the end of June. Luckily I decided to take care of things at the beginning of June so I had some time. Anyone can check and see which emissions tests have run or not run. You just need an OBDII scanner tool (you can actually go to an auto parts shop like Auto Zone and they will let you use one while you’re there). I have a mini laptop with a copy of HP Tuners that I can use to see if my tests have run or not. I’d been driving around for the last six months with no problems so I was very surprised to see that every test had an “inc” (incomplete) result. It’s very unusual for the tests to remain incomplete after so long. Just to be sure I did a GM drive cycle to see if the tests would run. Nothing. I racked my brain- it had been two years since my last test when there were no issues. What was preventing the tests from running?

And then it hit me- my tune! I checked pending error codes and found a P0103 code. This particular error code has to do with a malfunctioning MAF (Mass Air Flow) sensor. However, my MIL was off. Generally error codes like was I was seeing cause the MIL to come on. If the MIL is on then generally cars won’t run their onboard emissions diagnostics. I called my car tuner, Marc,  to see if he had any insight.

Sure enough, it was the new tune that was interfering with the onboard emissions tests. Usually cars use a MAF  sensor to determine the right amount of fuel to deliver to the engine. But my MAF just wasn’t up to the task so we switched to a two bar tune using a MAP (Manifold Air Pressure) sensor instead. When you make this change you have to tell the car to ignore the MAF sensor and this throws an error code (the P0103) resulting in the MIL coming on.  But Marc had programmed the car so that when the code was thrown the MIL stayed off (even though the car thought there was a problem).  Net result: The emissions tests didn’t run and weren’t going to run with the new tune. I was going to need an “emissions tune.”

I took my car back to the Marc and he created a new tune that used the MAF sensor (so no error codes). And then it was just a matter of driving until the tests ran. Since this was a “down and dirty” tune the car runs like caca. If you load and unload the engine quickly the car tends to die (this happens when you’re turning or stopping). And there surging issues,  rough idle and jerky acceleration. Luckily it only took two drive cycles to get the emissions test to run (well, all but one; I have never seen my EVAP test run on any of the Vettes I’ve owned).

After the testes ran I got the emissions inspection done, took the emissions & safety documents to the DMV and registered the car, and then took it back to Marc to have the old tune put back on. The car is now registered again, has the old tune and I don’t have to deal with this crap for another two years! Hooray! Sometimes I wish they’d go back to the old way where they just measure your tailpipe emissions… well, no- I’m sure that wouldn’t go well either.

Posted by Cam, July 1, 2011

Helpful Links:

Utah Safety & Emission Info

GM Drive Cycle information