| Author | Message | ||
     Jcjohnson33 |
I figured I would ask here since we all cover pretty much all things mechanical (engine). I’m trying to find the root problem for a 2000 Mitsubishi Galant 3.0 V6 FWD. I got the car from my father in law he inherited it from his step mom, the car has just under 58,000 miles on it. The car did have a valve cover leak when I got it. So I replaced the valve cover gaskets front and rear, spark plug gaskets, spark plugs, spark plug wires and air filter. Afterward I was running the engine and I noticed the front pre cat was glowing bright red. I shut off the car and the next day I pulled the front pre cat off and saw it was clogged because of the internals had melted some. I pulled all of the spark plugs on the front and none of them were wet or smelled of fuel. I ordered a new (California compliant) cat. Today I installed it and started the car so it could warm up (break in) the cat. However that cat also got super bright red so I shut off the engine. The rear pre cat doesn’t have this problem. Yes this car has 3 catalytic converters, 1 on each exhaust manifold and a third after the front and rear exhaust pipes come together. What else do I need to look for or check? | ||
| Gusm2 |
Quick Google check suggests it might be an excess of unburnt fuel getting into the Cat and igniting there | ||
| Hughlysses |
Has it got a distributor? If so, check the ignition timing. Excessively retarded timing can result in still-burning fuel/air being exhausted from the cylinders. | ||
| Sifo |
Is it the pre cat on both sides glowing? This was at idle? | ||
| 651lance |
How is the exhaust flow? Back in the day when I was a mechanic I’ve seen this issue and most of the time it was caused by exhaust air flow. We’ve seen the cats start to breakup and plug the pipe and muffler also plug the pipe. | ||
| Jcjohnson33 |
Sifo, yes this was at idle and no not both cats just the front. 651lance, I do know that there seems to be water from condensation coming out of the muffler, more than I would expect. I will drop the exhaust that connects the front and rear exhaust manifolds to see if anything is blocking flow. I’ll also check the timing. However the engine seems to run fine with no vibrations. | ||
| Sifo |
I reread your OP and saw the rear bank didn't have this problem, so it's limited to only certain cylinders. I would be suspect of a faulty fuel injector that's dumping too much fuel. It might be helpful to have the fault codes checked if you can. The amount of condensation in the exhaust can be surprising when it's still cool. I wouldn't be worried about that. | ||
| Rsh |
Do you have a code reader, Is the check engine light on or any codes stored? For the catalytic converter to get hot enough to glow red it is receiving an excess amount of raw fuel. I would check for a leaky fuel injector(s) that could be filling a cylinder or cylinders with raw fuel. If you have a decent code reader, you can monitor the oxygen sensor response for the affected bank for proper operation. Unfortunately you need to limit the run time or you will kill the replacement cat as well. | ||
| Natexlh1000 |
Sounds to me like an injector is drooling extra gas. How hard is it to swap the injectors around? My Dodge hemi was pretty easy. One thing to try: Take out the three injectors and fuel rail and lay them upon clean dry cardboard. Then turn on the ignition key without cranking it over. This will pressurize the fuel rail. If it's not cranking, NO gas should come out. If one is dribbling, that's your issue. I played this game with my Dodge to great effect. |
