1999 grand prix gtp no power

[BNaylor]

Originally Posted by n2racingcars

thanks for all the help. It was a clogged cat converter

Thanks for the feedback.

But what caused the CAT converter to fail prematurely? We have members with '99 and under GTPs that have well over 125K miles and still have the original CAT converter. How are you monitoring knock retard (KR)? I hope you're not still planning on running regular unleaded gas.

IMO running regular unleaded was probably a cause. Running fuel that is too low of an octane causes detonation or pre-ignition. Also, it causes carbon buildup. When detonation occurs combustion chamber temperatures increase to include what goes out the exhaust (out gases). With detonation the air/fuel mix ignites prematurely. Any unburned fuel goes out the exhaust right to the CAT converter. This unburned fuel will ignite in the catalytic converter causing the converter to run hotter. This shortens the catalytic converter's life.

[n2racingcars]

I am sure it was the gas. I will use premium from how on.