ello monte carlo experts.
i just bought a 2002 monte carlo SS
the car hesitates when there is strain on the motor (uphill or slowly accelerating)
i put new plugs and wires, changed air filter, cleaned MAS because check engine light was saying it was running lean. check engine light is off now but the issue still stands.
car specs say its supposed to run 0-60 in 8.5seconds.
i went to a test and tune and my 0-60 was between 10.8 and 11.5

suggestions please? i want to get it running right so i can start doing upgrades.
i want to turbo it eventually.

also if you have any simple performance upgrades i could try till i save up for turbo and tuning costs.

 

- What is the engine code? Even if the light is off, unless the code history has been cleared it can still be obtained.
- Running lean can be a condition of a vacuum leak. Easy to find, get a can of starting fluid, with the car idling, mist it on/around vacuum lines and gasket seals, if the car's idle changes (such as the RPMs pick up slight), you might have found a leak. Turn the car off and when it's cool to touch, check lines/hoses/connections in the region you sprayed to affect the issue.
- You informed this was a pre-existing condition before doing any work to the car, but if the plugs are BOSCH< get rid of them now. My experience with BOSCH plugs (not BOSCH wires, just plugs) is they are either bad from the start in a GM or give them 6 months and they will die premature. AC Delcos are best, NGK would be my second choice.
- You may want to have the CAT inspected for being clogged. A clogged exhaust means the exhaust can't escape getting the system backed up and is dangerous to the car. One way I heard as a "poor man's" test, pop off the upstream O2 sensor on the rear manifold (you don't want to do this long term, as the PCM cannot properly adjust the car's fueling, but it will do for a quick test by giving a secondary exhaust outlet). Another thing to do, after a ride in the car, with it running, look under it. If the cat is red or reddish in color, it's clogged.
Odds are with the age and I'm guessing near or over 100,000 miles, it would be good maintenance to change the upstream O2 sensor. Any car running a heated O2 should have them changed once in a while as the heating element does fail. I believe recommended change is between 70,000-100,000 miles. If you change it, go AC Delco or Delphi. Each O2 reads data a touch different to the PCM. The PCM was calibrated/tuned for AC Delco as that was the factory O2.

IMO those are the best items to start with at the moment. Get the actual engine code and we might be able to dig up more info.

 

Does your tach bounce at all when you are experiencing the issue? What gear are you in when it happens?

 

It was either 2000-2002 or 2001-2002 when GM got a bad batch of cats and they would swell under the extreme heat and close themselves up.

Usually hesitation/loss of power (especially going up-hill) is usually clogged cat related. Warm the car up sometime and crawl under it to see if the cat is starting to turn red or has a glow - that'll let you know if it's clogged, or you can have it pressure tested.

As Maniac said, have AutoZone scan your car as well. That's where I'd start.