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1999 Camaro Z28 Loss of Power Issues


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Hello! My name is Ian. I'm retired Air Force living in Spain with my American car. 

About 3 months ago my 1999 Camaro Z 28 with 189,000 miles, started sputtering, backfiring, losing power, in the SES light illuminated on and off.

Before then, the car would sometimes shutoff off it wasn't run in idle for more than 5 minutes and even would shut-off while driving.

C0237 and C0239 were the initial fault codes. They showed up as Airflow faults I do believe. After my mechanic tweaked a little bit the TPS senor and ran another diagnostic, the faults cleared, but the problem remained.

I would drive the car a little bit, take it back to the mechanic with all the same symptoms, yet no fault codes.

In the past 2 months we have switched out the spark plugs, put in a new TPS sensor, the connector, and replaced the Idle Airflow Sensor. Tested the senor and it has proper voltage and smooth idling. The mechanic checked all fuses and all checked good. He also air sprayed any dusty areas.

After doing further research, it appeared to have been a fuel pump issue. The fuel pressure read 35psi when is should have read around 58psi. The new fuel pump with new fuel filter reads at 58psi, but the problem still exists although it appears the car have a little not power.

There is no evidence of a fuel leak and no evidence of any oil leaking from the head gasket.

We are truly stumped with this one. Your advice or assistance would be GREATLY appreciated. I've been with this car since 2002 and am not ready to let her go, especially after all the money I put into her.



Your mechanic doesn't know big engines. From what you have said, it points to the air flow meter, and injectors. ONLY USE STOCK PARTS.

@motorcycleman please put your answers in the “Your Answer” section down below.  Thank you.

5 Answers

I have no idea about the quality of the gas in Spain but poor quality fuel can cause carbon build up on the fuel injectors. You might try using some fuel injector cleaner and see if that makes a difference.


Those codes don't seem to have anything to do with engine performance issues. Have you checked live data to see if it gives any clues as to what's going on?

Good question! I'll ask my mechanic.


Fuel filter, clean MAF sensor, new air filter, clean injectors, new PCV valve, clean or replace EGR valve.

Topic starter

Still nothing! 


Has the possibility of a clogged catalytic convertor been addressed?