Emissions Inspection on OBDII vehicles

TWINSCRW · Guest

OK guy this is just some helpful information that will save you some time. Any vehicle that is 96 and newer has OBDII and if you are in an area where emissions testing is required you need to plan before you go for inspection. Most of us run a custom tune in our cars to optimize power, well here is the thing with OBDII if you change the tune in your computer it takes approximately 600 miles befor the computer will go back into a state of "readiness" if the computer is not in this state when the inspection facility plugs into your diagnostics port you will fail inspection because the computer does not have enough history stored in it to say that your vehicle has been running fine. I hope this saves everyone time and aggravation at the inspection center.

Hollywood · Posted: Sat Mar 14, 2009 1:14 pm Post subject:

i tripped my check engine light again. so, it looks like im gonna have to do somn else.
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ScreamingFast · Site Admin Joined: Aug 17, 2008 Posts: 11380

Hollywood, are you running non catted Mid pipe? If so, you will not pass even with the sensors off or on. Crystal's car has a tune on it but she is running with cats. The tune did not cause her to fail emissions.
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TWINSCRW · Guest

its not the tune that will cause you to fail its changing the tune just before you go for inspection

PUN · Parts Changer Joined: Oct 19, 2008 Posts: 310

stang910 · Posted: Sun Mar 15, 2009 8:11 am Post subject:

Actually a tune can cause you to not pass an OBDII inspection. My VMP tune won't pass inspection cause all of the readiness monitors are turned off in the tune. Most tuners will leave all the functions of the computer on, but will turn off the rear O2 sensor since OR/H pipes are so popular. This will also cause you not to pass inspection cause the rear O2 readiness monitor will read "not ready" and this will not allow the computer to complete the other readiness monitors cause this is one of the first ones to be completed. So if your running an OR/H or X or even some low quality high flow cats you have to have run O2 simulators which work fine for 04 and down. For S197's the O2 simulators may not work for you since the computer actually looks for the sensors. I've seen some cars that they work on and others that don't. This is why you can't find O2 simulators for S197's. Also the older your car is the more "not readies" your car will be allowed.

Hollywood your not going to pass inspection with your OR/H pipe, but you can try the O2 simulators for 04 and down mustangs it MAY work for you. I also know of one more thing to trick the computer and its cheaper and will probably work better. I'll pm you the info if you like.

TWINSCRW · Guest

he still has the stock cats on the car ... the OR pipe is still in the box..... LOL

Hollywood · Posted: Sun Mar 15, 2009 9:53 am Post subject:

Hollywood · Posted: Sun Mar 15, 2009 9:58 am Post subject:

all i have is the intake and corsa mufflers. when they guy gave me a print out it shows my evap sytem, 02 sensors, catalyst and catalyst warmer systems "not ready" i cleared the check engine light and hoped it would stay off for the miles. but wheni hit around 45 miles after the clear, it trips the light again. so i know it could hurt my car but gonna try babyin it around on the stock tune and see if the light comes on. if not ill do it again. and if that doesnt work, ill just take my intake off and put everything to stock.... a pain in the azz, but a few bolts and 30 minutes isnt a bad trade off.
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stang910 · Posted: Sun Mar 15, 2009 2:28 pm Post subject:

Did you check the codes with your tuner? If you did what codes came up? Your axleback isn't going to cause a CEL, but your intake will. Since thats the only other mod you have I'd start there. Look at the connections and make sure you don't have a leak anywhere and all the clamps are tight. If you have a leak this will bring up a DTC MAF signal low.

stang910 · Posted: Sun Mar 15, 2009 2:37 pm Post subject:

I also meant to post resetting your CEL will not help you pass the OBDII inspection. When you do this you also reset the readiness monitors and you'll have to drive the car around til they come back up as ready. Usually takes about 15-30 minutes of driving hwy and city then the car will have to go through a cool down cycle and reheat cycle for all the readiness monitors to come up complete. The reason your CEL goes out for a period of time after a reset is because the readiness monitors are not complete which is what sets off the CEL in the first place. So if the problem still exists when the readiness monitor becomes complete you get a code once again. Post what the DTC is and I'll help you figure it out.

Hollywood · Posted: Sun Mar 15, 2009 7:35 pm Post subject:

i use my tuner to read it, but when i try to, it tells me there is an error reading the code. the only thing i can do is delete the code.
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Hollywood · Posted: Sat May 16, 2009 4:26 pm Post subject:

alright i tried gettin my inspection again... now instead of some working and others not ready... every single one of the tests, says not supported. i can get it passed visually, but this computer keeps kickin my azz!
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stang910 · Posted: Sat May 16, 2009 5:15 pm Post subject:

The tune you have has all emission related programs turned off which explains why your cel has not returned. Sound like to me instead of your tuner resolving the issue of your cel emission related programs were turned off in the tune.

TWINSCRW · Guest

there is a way to turn on the rear O2's without cats... you will need some anti-fowl sparkplug sleeves


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