what do plugged catalytic converters act like??

BadAndy

Founding Member
Feb 21, 2001
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Ohio
Will pluged cats cause detonation???, I have tried everything else on my stock dailydriver [ 95 GT] , fuel filter fuel pump, timming is 9, ran lucas fuel inj cleaner threw it

thanks
 
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Get a vacuum gauge. Measure it at idle, then rev to 2500, if you you get less vacuum at 2500, then that is a sign of clogged exaust. I have a backpressure gauge setup, but it isn't nessasary.
 
does your exhaust stink like something horrible? That would indiacate bad cats too. Sometimes too if your driving and your smelling exhaust. If the cats are plugged your exhaust has to escape some how so it will come out where your exhaust bolts to your headers.
 
90mustangGT said:
Get a vacuum gauge. Measure it at idle, then rev to 2500, if you you get less vacuum at 2500, then that is a sign of clogged exaust. I have a backpressure gauge setup, but it isn't nessasary.


did the vac test had 18 at idle and 20 at 2500rpm, maybe the cats are ok, the car is ok if i run mid grade gas so maybe i can deal with that
 
To answer your initial question: I'd imagine it'd be like that time that you were at the all-you-can-eat Mexican buffet and that Chimi' got stuck on the way out. Then when it unlodged, people thought you were a mason. :D




I'd do Jason's vac test but with a load on the motor (while on the highway, etc) if your car is driveable. Big difference between loaded and unloaded readings IMHO.

Good luck.
 
It will smell like rotten eggs. They can glow red too, but you might not see that if the shields are still around them. Take them babies off and put an O/R on anyways, the sound will be amazing.
 
When your cats plug up your car bogs down hardcore... until you reach higher rpm. You still have a loss of pwr there, and the cats get very hot. Mine didn't get red hot, but you could see smoke coming form them, and they would vaporize any water that would hit them after only being run for a few minutes in the driveway.

I pulled the h pipe and punched them out, much better. Have to buy new ones next year to pass smog :( But at least I have a off road h pipe that can poss visual inspection now ;)
 
90mustangGT said:
It very well could be carbon buildup in the combusition chamber. Cleaning of the injectors might be a good idea. What is the fuel pressure under load?


thats what im thinking, i did run lucas fuel inj cleaner threw it and many people say lucas inj cleaner works
 
Andy, the T4 processor (load-based 94-95 GT stick computer) is kinda famous for allowing the ping thing. Too much timing and too little fuel............

You would not be the first 94-95 non Cobra guy who had to run premium to keep pinging at bay.

Good luck.