I have an 87 IROC that didn't pass emmisions due to high NO's (HC and CO passed fine). I advanced the timing and put in EPP (Emissions Pass Protection). The timing was 2 degrees BTC and now is at 6 degrees BTC. Note, the plugs were burning white.
My question is, will the changes I did make a difference for the NO level?? It only missed passing NO by 60 PPM.
Thanks.

 

EPP, what's that? Is that one of those gas-tank additives? I used one, and I don't know if it was the additive or not, but I passed with flying colors.

Advancing should give you a cleaner burn, but it might also raise the idle speed. Where is the stock setting?

Were you sitting in a long inspection line? Your catalytic might've gotten loaded up...


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
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DRY GAS, DRY GAS! Isoproyl Alcohol. Dont waste your money on 'emmisions additives.'

What temperature is the car at during the test? Too cold will kick up hydrocarbons, too hot will kick up NOx count. 240 degrees is ideal for emmissions. Try to lower the temp of the engine. Attempt to keep the engine temp under 200 degrees (fan switch) to reduce the NOx count. Then add about 10 bottles of dry gas (about 50c a bottle) to less than a quarter tank of gas to compensate for the hydros.

[This message has been edited by blak92! (edited November 08, 2000).]

 

Thanks for the info men...........actually when I was first tested the car was running really hot 265+......was a problem all summer.....now that timing is at 6BTC its running a bit smoother, is down a bit on power, but definately runs cooler, never going above 200 degrees F. Blak92 it seems like what I have done might solve my problem, but to be sure to pass I think I will add the dry gas (how much volume per bottle?)you are recommending. Is there any risk of harming anything? TomP: The idle speed is fine, right at 750RPM.

 

Over 10% alcohol can damage your injectors. And many gas companies already add alcohol to the gas for emissions and for winter.

I would take the car on a long drive before you test. And don't let the car idle to long or it will go into open loop and run lean.

I would say that you've already done enough to pass, as you were just barely over. I think your REAL problem may be your EGR. That is the usual culprit when you fail based on NOx.