richn95136

I was wondering if anyone can please help! I have a 1995 Lumina 3.1. When it is park and I press the gas the car seems to run OK. But when I put the car into gear and accelerate there is hesitation/stumbling/surging thoughout the entire driving range thereafter....At the same time there is this dreadful whistling noise which starts when after I put the car in gear and have driven a mile or two and the engine is heated up....The noise is REALLY loud. The whistling/skreeching starts as one high pitched sound, then another whistle in a different octave, then another in a different octave, etc. until there are 3 or 4 whistles simualtaneosly....the faster I try to go, the louder the whistles, the more hesitation/stumbling, the less engine power I have.....It almost sounds like some kind of obstruction in the fuel injection, a faulty EGR valve or an intake manifold leak. The funny thing is, after I have driven it to the point of whistling and put the car in park there is no hesitation or stumbling when I step on the accelerator, and I have to go to a very high RPM to get the noise to start when it is in park.....PLEASE HELP!

Shortbus

Sounds like maybe a plugged cat. convertor. This could be making the whistle and would certainly cause a loss of power.

richn95136

thanks for the reply.....this whistling/skreeching seems to be coming from the engine....not near the cat. converter.....but there is light backfiring into the engine when I accelarate quickly and let off (when the car is in park)....everything gets much worse when the car is under load and heated up....

Shortbus

Looking into some service bulletins, got a question for you.
Is the <strong>Service engine Soon</strong> light on?

richn95136

No....the check engine light does not come on, which is baffling. I was thinking of getting a cheap OBD 1 scanner and drawing the codes, but since the light wasn't coming on I don't think the PCM is going to give me any information....

richn95136

Question: What would clog the catalytic converter? Foreign material that found it's way into the ehxaust system....or normal wear and tear/build up?

Shortbus

Usually carbon build up. Most convertors these days have a honeycomb screen inside of them, these honey comb screens are coated with platinum to aid in superheating the exhaust to help burn any HC's left over from the combustion process.

Sometimes the screens melt or collapse inside and partially or completely block the path of the exhaust, which can create enough backpressure that the engine cannot breath well enough to run properly,
eventually the entire inside of the convertor will melt and sometimes shoot sparks and out of the exhaust.

richn95136

....But can that cause the whistling sound to appear like it is coming from the top of the engine? Also how come when my car is in park and I accelerate the symptoms aren't as severe as when the car is in gear and under load?

richn95136

To John (GM modulator),

Thanks a million!.....You were absolutely correct about the problem being the catalytic converter.....the honeycomb filter inside was completely melted!.......My car is running great now.....Thanks again!

Shortbus

Glad to hear that.
Thanks for letting me know.

John