Can anyone describe the sound of a bad cat?
06-12-2006, 07:29 AM
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Can anyone describe the sound of a bad cat?
I'm going through a '91 200 tubo non-Q I just bought. It has an auto trans with 132M. The PO had "a gear put in the differential for $600". He didn't know what the name was but I'm thinking ring gear? All this being said because I'm not sure if what I'm hearing is the cat making this noise or the trans/diff.
What happens is upon early acceleration I get this almost pinging/growling noise similar to low octane fuel noise and upon harder acceleration a louder knocking noise enough to feel under the drivers floorpan or in the tunnel, until around 2500 rpm. Then when I accelerate harder it really dies @ 3000 rpm like the engine is choking,no power at all(this symptom got worse after putting in new injectors). I back off the gas and it smoothes out. Constant highway driving no problem. I've tried disconecting the sniffer tube it did not run better but seemed like a good amount or pressure coming out of the tube(I have no way to measure it).I can't keep the injectors seated(backpressure?) They get blown out of their seats it seems. Unburned gas puddles under them after a test drive.
Can anyone describe the sound or know of a definitive test for bad cats? It looks like the PO had new pipe from the exhaust manifold to the rear exhaust(no center muffler). I can't tell if the cat was done or not. Thanks for any help.
What happens is upon early acceleration I get this almost pinging/growling noise similar to low octane fuel noise and upon harder acceleration a louder knocking noise enough to feel under the drivers floorpan or in the tunnel, until around 2500 rpm. Then when I accelerate harder it really dies @ 3000 rpm like the engine is choking,no power at all(this symptom got worse after putting in new injectors). I back off the gas and it smoothes out. Constant highway driving no problem. I've tried disconecting the sniffer tube it did not run better but seemed like a good amount or pressure coming out of the tube(I have no way to measure it).I can't keep the injectors seated(backpressure?) They get blown out of their seats it seems. Unburned gas puddles under them after a test drive.
Can anyone describe the sound or know of a definitive test for bad cats? It looks like the PO had new pipe from the exhaust manifold to the rear exhaust(no center muffler). I can't tell if the cat was done or not. Thanks for any help.
06-12-2006, 08:12 AM
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my experience.............
my cat had a rattle at idle. This was proly the broken material inside the cat bouncing around as the exhaust gas flowed thru the cat. It had the sound of small pebbles being shaken inside a tin can. I drove the car for years that way until the material finally formed a plug inside the cat. When that happened, there was so much gas flow restriction, that the car would not go faster than 50 mph on the interstate. I don't know what the rpm limit was at 50 mph. I had to drive nearly 300 miles at the slow speed, mostly on the berm of the interstate. Dodging road kill and tire carcasses was no fun. Replacing the cat, fixed the problem.
06-12-2006, 10:17 AM
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Re: my experience.............had no rotton egg smell.........
never noticed the cat getting super hot, but I am sure when it plugged up, it must have gotten super hot.
With your car lacking h
With your car lacking h
06-12-2006, 10:24 AM
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maybe not a bad cat............but a plugged fuel filter..............
it may be that you have a plugged up fuel filter, or a fuel pump that is going south. You may not be getting enough fuel to the motor.
If it has been a long time since the fuel filter has been replaced, do that first. That just may fix your problem.
If it has been a long time since the fuel filter has been replaced, do that first. That just may fix your problem.
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06-12-2006, 10:38 AM
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Re: Injectors blowing out. Extreme backpressure for sure.
These injectors were my first experience with installing injectors. I am assuming there should be pressure sucking them into their seats rather than the opposite, right? I used quite a bit of force to push them into their seats. I smelled unburned gas when I opened the hood and found 2 of the injectors were unseated with a pool of gas under them after the road test. Do you think a bad cat could cause this?
Thanks,
Steve
Thanks,
Steve