Thread: Grand Prix 3.8L will not go faster than 70km

flashing cel means one of 2 things.

either you need a tune up real bad. or the cat is clogged up good.


what kind of miles you got? and last known tune up was?

A new cat would be the best way. You could go catless but it wil throw a rear o2 code.

if you have the cat removed the cel light will stay on forever for the rear o2 sensor, unless you have it tuned to not report.

or replace the cat.

you can drive the car as hard as you dare for a bit at night, then pull over and look at the cat, if its glowing red it clogged. or bang on it when its cold, if you hear it rattling its broken inside.

you can also pull the up stream o2, rear manifold back of the engine. this will make a good exhaust leak but if it runs better the cat is clogged for sure.

at 230,000 miles if you guys didnt do a tune up when you first got it, im sure its time. first thing i like to do when i get a used car is start my own new service records. cant always trust what a sellers says.

and the trans would thank you im sure if you did a pan drop and filter to it. at those miles most dont last that long, ( unless its been serviced regularly its whole life) so chances are its a rebuild or used unit swapped in at some point in its life.

also make sure you do your oil changes, old engines need extra love. dont trust the oil % thing in the car, set the trip and change it when you hit 3,000 miles or so.