2002 Chevy Monte Carlo SS 6cyl

Symptom, loss of horse power (from a stop and going uphill), surge or lunge forward when accelerating (misfire?), rough idle (occasional knock).
Maintenance, regularly change all filters and fluids, recently had the m.a.f cleaned and changed air filter, spark plugs and wires, oil. Fuel pressure regulator changed about one year ago.

There have been times in the past year or so when the car would crank but not start. Especially when the car was hot. Wait a couple minutes and it would start. Also a couple of times the car would shake fairly hard when started, get up to speed and it was fine.

I have had people tell me anything from a clogged catalytic converter to bad fuel injectors or fuel pump.

Scanned the car last week. No codes showed up. Never had a Check Engine Light.

**I forgot to mention that every once and a while the car will jerk forward when accelerating. A coworker said his truck did the same. Our mechanic said it was the fuel pump. I will see what that does for him.

 

Next time the car is warm and wont' start-up, unplug the MAF sensor harness and try to start it again. If that works, the MAF might be dirty and/or bad

 

You mention a lot of symptoms that would be present if you have a clogged cat converter. When the car acts up take a look at the cat converter. If it is severely clogged it will be glowing red or orange. Another thing you can try is to remove the O2 sensor located in the exhaust manifold and see if you regain some of the lost power during acceleration and pulling hills. One other thing you can do is connect a vacuum gauge to the engine and observe the reading. It should be steady at idle. If it fluctuates while the engine is idling that is another sign of a clogged cat converter. One last thing you can do is take the car to a shop and have them measure the pressure in the exhaust system before and after the cat. Excessive pressure prior to the cat and low pressure after the cat would indicate a restriction.

 

Thanks for the advice. I will take the car in next week.

 

If you have access to a infrared thermometer you can check the catalyst efficiency. Simply measure before and after and see what the variance in tempeture.

a clogged fuel filter can cause similar issues.

It could also be a fuel pump going out.

Check for the 3 basics, fuel air and spark.

If your able to, get any On Demand DTC's or CMDTC's (Continuous Memory DTC's)

 

I measured the cat convert temp. The front was 190 and the back was 150 after a short trip. I will test it after a longer trip.

 

Im with Mike (chibi)

Id unplug the MAF....and see if that eliminates your problem...
If it does, Replace the MAF...But I dont recommend driveing your vehicle with the MAF unplugged for any length of time...other that testing purposes.

 

Clogged Catalytic Converter. They don't throw codes, just totally destroy the drivability of the car until it won't get out of it's own way. I've had several clog on me.

 

A catalyst should have a noticeable difference in temperature. Like 30-50* difference.

Take a good 20 min drive, get it nice and hot, and check it again

 

I took a 40minute trip and when I got back I checked the temp. The front was around 250. The back was about 190.