2001 Cavalier Engine Problems

if there is a strong odour then its getting too much fuel.

it could also be the EGR valve has stuck this will give you the same symtoms you describe, If you can find it i can tell you how to disable it, but in doing so you may fall foul of any anti pollution laws.

also look at

http://cr4.globalspec.com/thread/53253/2000-Cavalier

this link will possibly depress you look at one of my last postings re common fault

http://cr4.globalspec.com/thread/53689/2001-Chevy-Cavalier

hope this helps if not please give us more information and someone may be able to help.

http://chevroletforum.com/forum/showthread.php?t=21595

http://www.vauxcentre.co.uk/index.php?option=categories&category_id=157052&category=Vauxhall%20EGR%20Valves

this describes the solotion to the blanking off the EGR but remember the poloution bit it will fail a test.

http://www.vauxhallownersnetwork.co.uk/showthread.php?157590-Blanking-Off-EGR-Valve-on-a-2001-Zafira

http://www.carjunky.com/messageboard/data/422.html

What the EGR valve does etc

http://en.wikipedia.org/wiki/Exhaust_gas_recirculation

EGR Valve on Google

http://www.google.co.uk/search?hl=en&rls=com.microsoft:en-gb:IE-SearchBox&q=exhaust+gas+recirculation+egr+valve&revid=27246733&ei=igLbS-AmmuqbA_-yzWQ&sa=X&oi=revisions_inline&resnum=0&ct=broad-revision&cd=3&ved=0CDoQ1QIoAg

Two other possibilities that come to mind, poor spark, or poor compression.

I am leaning more towards poor spark as you will still have mediocre power on the low end but upper end under load power will be very poor. (Back in the day we called it spark blow-out)

Although, I must agree with Peter, could be stuck EGR valve.

Sounds to me like you have a problem with a sensor possibly the airflow meter or maf sensor depending on what medium your computer uses to measure air flow. were you traveling over rough ground or a bumpy road? it is possible that there is a leak between your engine and air flow meter or if your car has a maf/map sensor it may no longer be receiving a signal from your manifold. Plastic/rubber hoses perish and become brittle with age and considering the amount of miles your car has done it is very possible that its as simple as a broken or split hose. if your car has multi point fuel injection i doubt the manufacturer would have utilised a egr pipe as this is a system that is predominantly fitted to engines with a carburettor due to there poor fuel metering.

also when was the last time you serviced this vehicle?

A mobile mechanic with the correct scan tool will be able to connect to your cpu/ecm and quickly diagnose the fault.

Please not that i am not familiar with American emission control regulation and your car may very well have a stuck egr valve but if this is the case it should not cause the severe problems you are having, in my experience a stuck egr only drastically affects idle

This can be confusing, but lets try it. The indication you describe of the plugs showing a "black" appearance would tell us the engine is getting too much fuel. The computer gets a signal from the oxygen sensors that it needs to increase injector on time thereby giving a richer mixture. So it does, but this can be in response to a lean condition sensed by the oxygen sensor(s). The lean condition could be caused by many things among them , a large vacuum leak, or an uncontrolled air flow into the intake. I realize it is sometimes difficult to accept a lean condition causing your vehicles problem, but it is something worth investigating since todays computer controlled fuel systems compensate for many hidden problems. Will offer addl suggestions as soon as My mental library catches up to my keyboard.

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Thanks for all the suggestions,i am considering several of them.the spark doesnt seem to be the problem as the engine runs fine under no load i.e. (sitting in park).I had thought of one of the coils not fireing but both coils were replaced less than 12 months ago.Also i switched the coils around but to no avail.Will a intake manifold leak cause such severe problems?I am going to try a old trick using a can of ether and spray around the intake and throttle body while its running.any ideas on if the catalytic converter being clogged will cause such problems?thanks for all the help.

Usually if the converter is restricted , the engine just won't run any higher in spite of how much gas you give it load or no load.