I read on the board that this might be a problem. My check is coming up in a couple months, and I'd like to know

 

Do you have your emission devices in place?
What modifications?

 

Make sure the tuner isn't removing emmissions checks.

That will make it fail the plug in OBD2 test.

 

Ion you tuned it i had to have it tuned for the A4-M6 swap, and you tweaked it. Emmssions things should have been taken off

 

Sorry... it was a year ago after all. You will pass without any problems as far as programming is concerned.

 

Uh Oh! So if you do not have your AIR and EGR hooked up, are you still able to pass the OBD2 plug in emission test with computer tuning? I thought I would be able to have them tuned out so I could pass???? Now Im worried!

Could someone please enlighten me on this.....please!

Thanks,
Rich

 

If tuned properly and the smog station is only doing EPA I/M tests with a PCM scanner then most mod'd cars can still pass.

I have gotten cars without CATs or SC'd with larger injectors to pass the I/M tests.

Pre 2001 cars are allowed up to 2 of the IM tests to fail.
01 and newer only one test allowed to fail.

Most cars fail because the owner pulls the battry or deletes DTC error codes which forces all I/M tests to revert back to a Non Complete (failed) state and now can take up to 40 valid drive cycles for some tests to get back to a Complete ( passed) state.

 

Been a little busy with work but wanted to say thanks for the reply.......THANKS FOR THE REPLY

 

Not to change the subject, but is there a published procedure to get the computer back to a complete state? I have a 2000 Silverado w/ the 4.8 and have exactly that problem. I cleared a code about 3 months ago. Took it for a smog test and failed last weekend. I just don't know what area of the self test the truck is not comleting. I do know the truck is not completing the cat, egr, and fuel evap tests. Any ideas?
Thanks
Todd

 

Some tests such as CATs and AIR which are tested only once per drive cycle can take as many as 40 cycles to complete.

A valid drive cycle must start below 120 water degrees and must exceed 160 degrees ( if someone did not tune and change open/closed loop values)
EPA did this so someone does not just turn key on/off 40 times and trick the test to complete.

If the engine makeup and/or tune prevent getting to lets say 160 degrees then the tests would take many more drive cycles to complete, esp in cold weather.

To speed up most relearn of PCM you start with open loop, let idle till closed loop engine, use half throttle to get to 55 MPH.
Stay at 55 for 5 minutes then without using brakes or shifting let engine get below 20 MPH
Then use 3/4 throttle and repeat and after 5 minutes at 55 MPH let car coast to stop, idle a few seconds and turn engine off.

This does NOT cause all tests to relearn but most of them.

 

Thanks for the info. I'll give it a try. I just need to get the thing passed the smog check before the end of the month (at least I have more time than normal!)