Cat problem? Any help/suggestions?
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Teching In
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Cat problem? Any help/suggestions? Have a bone stock (minus fuel pump) 2000 LS1 TA 76k, keeps giving me a 0420 code and has always seemed to run a bit hot, 210 F which most tell me is normal, but even with the heat on high out on the highway and in cold weather? I put a lower stat in it, which was a 165 I think, but it was running a bit too cold, so put the stock 1 back in. With the 165 stat the 0420 code did NOT come on, which I think would be just the opposite, that the colder it ran the colder the cats would be and thus not get hot enough to work.
Anyway the car idles a bit rough and then the 0420 comes up and some times won't start on the 1st turn of the key, so I thought it was a bad coil, but now am thinking the cat/cats are bad, which might explain it running a bit hot, also the slightly rough idle and maybe it won't start right off because of back pressure/exhaust not being able to get out? Also I get some knocking under harder acceleration, again thought it was coil but now am thinking its clogged converter. So should I try a converter cleaner 1st or knock out the comb, which will probably keep my check engine light on, which is fine as long as the car is running/breathing good, how much more HP will I get without cats and is it worth it and since that will probably set off my check engine light, is there anyway to get it to turn off?
Thanks
Anyway the car idles a bit rough and then the 0420 comes up and some times won't start on the 1st turn of the key, so I thought it was a bad coil, but now am thinking the cat/cats are bad, which might explain it running a bit hot, also the slightly rough idle and maybe it won't start right off because of back pressure/exhaust not being able to get out? Also I get some knocking under harder acceleration, again thought it was coil but now am thinking its clogged converter. So should I try a converter cleaner 1st or knock out the comb, which will probably keep my check engine light on, which is fine as long as the car is running/breathing good, how much more HP will I get without cats and is it worth it and since that will probably set off my check engine light, is there anyway to get it to turn off?
Thanks
Last edited by muttleys2000whiteTA; Mar 19, 2016 at 11:06 PM.
Could well be the cat brick is:
Clogged.
Melted.
Converter cleaner??
Injs dumping fuel, can kill the cat, cause rough idle, hard start.
A complete check of all engine sensors, fresh O2's, clean injs, fuel psi check, are some of the items I'd be looking at.
Clogged.
Melted.
Converter cleaner??
Injs dumping fuel, can kill the cat, cause rough idle, hard start.
A complete check of all engine sensors, fresh O2's, clean injs, fuel psi check, are some of the items I'd be looking at.
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Joined: Apr 2002
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From: So.Cal.
Cat problem? Any help/suggestions? The test for P0420/P0430 will only run under certain conditions: ECT must be sufficient (above 170F if I remember correctly), after 3 minute 55 mph drive and not coasted down to idle, O2's are in good condition with no codes...
the alightly rough idle you detect is the test being run... PCM drives an EQR pulse/transitition and measures the response time of rear O2 relative to front O2, if response time is too short then DTC is set.
So P0420 indicates bank 1 cat is not able to catalyse... this does not say anything for other bank cat, it could well be partially clogged.
Either way youhace cat problems.
the alightly rough idle you detect is the test being run... PCM drives an EQR pulse/transitition and measures the response time of rear O2 relative to front O2, if response time is too short then DTC is set.
So P0420 indicates bank 1 cat is not able to catalyse... this does not say anything for other bank cat, it could well be partially clogged.
Either way youhace cat problems.
