I'm at my wits end about this! I've been chasing this noise for long enough. Here's the symptoms: the noise sounds like a cross between detonation,exhaust leak,lifter ticking and chattering. The exhaust has been changed twice with 2 different sets of Edelbrock headers,2 different cats and 2 different catbacks. No leaks have been found and all gaskets are good. There's no ticking from the engine at all. The only time the noise is present is when the car is in gear and accelerating from a stop and through the gears until cruising speed is reached and then it is still present but faint. The noise seems to be centered around the cat converter where the Y pipes merge to enter the cat. I've thought of having a new Y pipe made with a test pipe in place of the cat to see if it could be just turbulence in the exhaust but haven't found a shop willing to do the work. I've considered replacing the torque converter and flywheel but I'd hate to do all that for nothing. GM Tech has suggested pouring Top Engine cleaner into the engine to clean out the carbon that could be the source of the noise but the dealership parts people say it could cause damage to an engine with over 100,000 miles(mine has 130,000) and recommended Marvel's Mystery oil instead to be put in the tank,in the oil and poured in the TB. Does anyone have any suggestions? Can anyone help with this?



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Mongoose-NCTGA-1990 Pontiac Formula/305 TBI-700R4 with Edelbrock Performer TBI intake,TES headers,and STB,K&N,MSD-6AL,Holley laser shot coil,Accel Extreme 9000 wires,Jet Stage 2 chip,TCI shift kit with corvette servo,Richmond 3.73 gear with Auburn 3 series posi,3" high flow cat with SLP 3" cat back,Eibach sportline springs,Energy Suspension poly throughout,Lakewood LCA and adjustable panhard bar package,SSM subframe connectors,IROC wonder bar,Tokico 5 way adjustable struts and shocks,Autometer electric fuel pressure gauge,Alpine,JL Audio,MB Quart,92 GTA taillights,92 GTA aero wing and hatch,Steve Spohn LCA relocater kit,MacEwen White face gauges,84 T/A cold air induction air cleaner.

 

hey man my squealing noise i thoght was in the tranny, take it to the dealer and have them unbolt the TC and have htem start the engine, if its still there ,its not the tranny, thats what they did with my camaro iroc-z. IT only cost like 79 bucks, cheaper than replacing the torque converter for nothing.

 

Can damage an engine with over 100,000 miles? Hmmm, isn't it ususally the ones that have more than 100,000 miles that need it though? Maybe it is the Torque Converter bolts. My old Sunbird did that. Rattle on accel only. I would pull the flywheel cover and check all three bolts.

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"I used to have a handle on life, but then I used it as a plunger and broke it" -The Wave

ASE Master Tech + L1
Savannah, GA
'87 Trans Am-K&N,Cold air induction, SSM SFC, Flowmaster, 16" GTA rims.
'97 Bonneville SSE
About Me

 

One of the problems that I was told could happen is that the engine could develop blow by if I use the cleaner. How many cans of this stuff will I need? The parts dept. said I would need 2. Anyone else got any suggestions?

 

Well, IIRC, Top end cleaner, Marvel, tranny fluid, and water, poured through the TB all work on roughly the same principle. They create steam in the combustion chamber and loosen the carbon deposits in there. I would do both the water/etc./etc. through the TB and run marvel in the oil (for only 1,000 mi. max.). Also if you have an air tube on your cat, you may want to trace back saring from the connection to the cat's air tube back to the switch box in the engine, these act funny at times, also sometimes people inadvertently leave some debris in the stock air tube at the point of the cat connection. Depending on how bad he stock exhaust died you may have anything from just a ridge to a circular piece of metal still in the tube. Hope that helps, good luck.



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If you have a problem,
If no-one else can help,
And if you can find them,
Maybe you can hire....
THE A-TEAM

 

IIRC,
I ahve the same headers and have experienced the same type of noise.
I first thought maladjusted rockers, then exhaust leak.
I cann't hear any noise with the car stationary, regardless of RPM.
I put it down to exhaust pulse resonance in the headers and have decided to live with it.
The only problem seems to be that my knock sensor reads this as knock.
I get 2-3 knock events on a WFO run, 2-3 on WFO 4th gear acceleration from 1,000 RPM and 30-50 knock events on a 3,500 RPM downshift.

 

Could the Y pipe be rebuilt to correct this? I've had a Flowmaster Y pipe that will join 2 2.5" pipes to merge into 1 3" pipe but as usual,in this area(Charlotte,NC is the nearest large city) no one wants to mess with it since it involves removing the cat to do it. I have also thought this was the problem but now I want it gone. Perhaps someone maught know of a shop within say 50 miles of here that might be able to do the work?


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Mongoose-NCTGA-1990 Pontiac Formula/305 TBI-700R4 with Edelbrock Performer TBI intake,TES headers,and STB,K&N,MSD-6AL,Holley laser shot coil,Accel Extreme 9000 wires,Jet Stage 2 chip,TCI shift kit with corvette servo,Richmond 3.73 gear with Auburn 3 series posi,3" high flow cat with SLP 3" cat back,Eibach sportline springs,Energy Suspension poly throughout,Lakewood LCA and adjustable panhard bar package,SSM subframe connectors,IROC wonder bar,Tokico 5 way adjustable struts and shocks,Autometer electric fuel pressure gauge,Alpine,JL Audio,MB Quart,92 GTA taillights,92 GTA aero wing and hatch,Steve Spohn LCA relocater kit,MacEwen White face gauges,84 T/A cold air induction air cleaner.

 

I hear Meck Co is toughest county in state on emissions so figures. Your so close drive to south of border SC, checked them out?

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-Jimmy-
91 Formula 5.7

 

I've found 2 shops(1 here in Monroe and one in Charlotte) that are willing to do it as long as the cat is retained. My father in law has offered to hook me up with a shop in Cheraw that could possibly help as well. The biggest problem is working with 3"pipe. I want to use the Flowmaster Y pipe that I have to replace the "squish" that Edelbrock uses to smooth out the flow and hopefully stop the noise. The other problem is that I have SSM subframe connectors that make it a tight fit.
Maybe they could notch the connector to make the pipe fit?

 

Take a look at the spring in the starter solinoid. I've seen the return spring broken and or missing thus causing the starter teeth to hit the fly wheel on accell. It then backs off as you get up to cruse.
I.R. ASE .. LOL but true