Emissions Test With Stage One

[2step]

Anyone had their GT with Stage 1 go through an emissions certification test yet. Here in Texas, new cars go for 2 years before required testing. Then every year after that. Mine is an '04 w/S1 so who knows what mods my motor will have come test time.
I know each area of the country has different testing but I just want to get an idea of how much latitude we have. [:I]

[MichaelDay]

I understand that the tailpipe test should come out OK. The problem could come from the tests that plug into you OBDII connector since some of the parameters are not monitored by Stage 1. I have yet to get hear that someone actually passed (or failed for that matter) a smog test that required plugging into the OBDII. As you know, the tests in Texas vary by county.

[bigtommy83]

Here in Milwaukee WI, all they do is the OBDII and the gas cap pressure test. They don't do a tail pipe test unless it is 95 or older. All it takes is a few bolts and you are "legal" again.

[MichaelDay]

It is certainly easier to just swap out the PCM on the '04 since that is all that there is to Stage 1. If you had an '03 the injectors would also be different and I am not sure how the stock PCM would fair with the unexpected larger injectors emission wise.

[PTGT Redman]

Anyone swap their stock PCM while leaving the larger injectors?
Are there subtle 04 GT vs 03 GT programming differences cause the S1 injectors are the same as the stock 04 injectors.
Thanks, b/c i'm prolly going to have to have my car emission tested and want to have an idea as to what I need to do.

So, NH does OBD testing, not tailpipe.
Should I or do I need to swap out the S1 PCM?
If I do, and leave the S1 injectors, will I still get appropraite parameter readings from the PCM if it is tested?

[SuGamer]

I would assume that there would be no problems with leaving in the larger injectors. After all, they are just injectors whether they are higher flowing or not. It's not like the injectors are mechanically complicated. I would assume that even if the injectors are larger, the stock PCM would still use the fuel flow rate that it's programmed with. Just my opinion, I might be wrong.

[MichaelDay]

Although I don't know the answer to the question, the stock PCM on the '03 would assume that the stock injectors were in place and probably cause the larger Stage 1 injectors to push too much fuel making a richer mixture. Since the GT runs somewhat rich anyway, I wouldn't think that would be a good thing for emissions. The PCM might or might not know to back off the mixture. I'm not sure the OBDII test would know the difference for a short time which MIGHT allow you to pass the test. Unfortunately, all this is just conjecture until someone actually either passes or fails the OBDII test with Stage 1 in place or with the Stage 1 injectors and the stock '03 PCM.

Unfortunately, I don't know anyone with an '03 that has tried it either way to find out.

[PTGT Redman]

Hmm, I'm wondering since I haven't registered yet in NH, if I can have my car checked off the record.

[Cal Cruzer]

quote:Originally posted by MichaelDay

Although I don't know the answer to the question, the stock PCM on the '03 would assume that the stock injectors were in place and probably cause the larger Stage 1 injectors to push too much fuel making a richer mixture. Since the GT runs somewhat rich anyway, I wouldn't think that would be a good thing for emissions. The PCM might or might not know to back off the mixture. I'm not sure the OBDII test would know the difference for a short time which MIGHT allow you to pass the test. Unfortunately, all this is just conjecture until someone actually either passes or fails the OBDII test with Stage 1 in place or with the Stage 1 injectors and the stock '03 PCM.

Unfortunately, I don't know anyone with an '03 that has tried it either way to find out.

Not sure about passing smog but you are right about the car running rich. The PCM has the injector size programmed into it. It interprets the sensor inputs and sends a signal to the injector for a pulse width @ a given fuel pressure. A bigger injector will flow more at a given pulse width and you will run richer. Same if the pressure is greater than is programmed.

[Hot Wheels]

I swapped the stock PCM back into my 2003 and left the S1 injectors in place. I drove the car about 300-350 miles before the OBDII plug-in test (engine was not started). The car passed. I drove the car another 400-500 miles with the stock PCM. At that point I started getting mid to high rpm hesitation/miss and discovered that the plugs were fouled. I changed plugs to the NGK V-Power LZTR5A-13, stock number 4306. These fouled, too. I finally reinstalled the S1 PCM and cleaned the plugs. I haven't had any problems since switching back to the S1 PCM.