1998 Mustang GT Problem Can Anyone Help

Sounds like a clogged - worn out convertor. Good excuse to replace it with a high flow X or H catted pipe..

Red mustang Gt 46 said:

Sounds like a clogged - worn out convertor. Good excuse to replace it with a high flow X or H catted pipe..

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YUP!!! What he said...plugged up catalytic converter. I reccomend an X-pipe with cats as a replacement.

I melted some cats on an old T-Bird I used to own... Did the same thing as you described. Supposedly it happened because my fuel filter was clogged and I was running way too lean. At least that's what the mechanic said.

I hope you don't live in California...

When the light flashes, it means something is wrong that could cause catostrophic damage to the cats...

a catalytic convertor usually will not go bad on its own tho. they fail b/c of some other problem with the car. so replacing the cat/h-pipe with an aftermarket unit will not completely solve the problem, it could be anything from a fuel filter like the guy before me said, to oil fouled plugs, etc. once you fix the original problem u could use this as an excuse to get a high flow/off-road h or x pipe tho?

chevyboy_z28 said:

a catalytic convertor usually will not go bad on its own tho. they fail b/c of some other problem with the car. so replacing the cat/h-pipe with an aftermarket unit will not completely solve the problem...

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The Chevy guy is right. Are you a GM certified mechanic? Good job.
Yup, something is already wrong and it destoryed the cat. Have you ever changed the fuel filter? Don't start swapping crap out at random; get a new catalyic converter but only install it after you have resolved the problem. This probably needs a "real" mechanic to diagnose.

As recommended, take it to a qualified professional.

After that, install an Off Road midpipe.

Get E Up 98 said:

...I was told I have 6 cats on my car by a muffler mechanic...

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not quite, theres 4 convertors and two resonators. although the resonators arent as restrictive as the thick honeycomb designed catalytic convertors, they too hamper the exhaust note but dont get clogged like cats do so they dont pose a problem. as stated before an offroad x or h midpipe will eliminate all that junk and help your car breathe enhancing overall performance, but you gotta get the main problem tackled first.

back to the main problem; as for the cat being tested and checking out ok, ide say that you got lucky. see the only assumption i can make is that when your egr (exhaust gas recirculation) hose blew off it created a rich condition b/c those exhaust fumes were no longer being pulled back into the intake and reburned, instead they flowed down thru the manifolds and thru the cat. i bet it was the left cat that was glowing, b/c that the side that the egr hook up is on. i believe the hesitation came from the computer sensing this rich condition from the O2 sensors and pulling spark/retarding the timing (hence the car running like crap). i say your lucky b/c the cat would only survive for so long with a rich condition like i assume you have until it clogged up. this is all off the top of my head and happens to be the best conclusion i can come up with... and no im not a GM certified mechanic, but i did stay at a Holiday Inn express last night !...let me know how things work out, im interested to know.

$12.00... have you replaced your fuel filter...? it's a cheap fix so if it's not that, what have you lost but a couple bucks. How many miles do you have on your car? Has the filter ever been replaced?

I had the same issue, minus the hot cat, it turned out to be my fuel pump was pushing out 24psi instead of 35-40. I just ordered the new pump, I'll let you know if it works

JDW