Cat Is Red Hot And The Engine Is Bocking Alot

[honduraneclipse]

JUST REPLACED HEAD GASKET FIXED THE TIMING AND THE CAR WAS STILL SHACKING AND BOCKING ALOT ....SO WE REVVED THE ENGINE HIGH TO SEE IF THE CAT WAS BACKED UP..... RED HOT BLAZING RED.... NO WANDER MY CAR HAS BEEN IDLING BAD... ANYWAYS MY DAD WORKS AT A BODY SHOP AND WE HAVE 3 MITSUBISHIS OUTBACK... HE WANTS TO TAKE OUT THE CAT FROM ONE OF THOSE AND PUT IT ON MY 90 GST .... 1 OF THEM IS A 91 GSR GALANT AND THE OTHER 2 CARS ARE 1ST GENERATION 1.8 .... MY QUESTION IS ARE THESE CATS GOING TO WORK FINE WITH MY CAR ... MY CAR IS STOCK EXCEPT FOR MY 2.5 INCH CUSTOM CATBACK...

 

[TimG]

I'm not sure, but maybe you are running rich and the fuel is igniting within the cat?

 

[jpolizo]

This doesn't exactly answer your question, but I had problems with a Ford (stop laughing) wherein the cat was doing the same thing you describe; in fact, it melted. The problem turned out to not be the cat but the FPR which was allowig way too much fuel pressure and the thing was running way rich. The cat was trying to eat all those hydrocarbons and that's why it was got so hot.

I point this out as you might want to see if you have another problem someplace.

Best of luck.

 

[honduraneclipse]

thanks guys for the input im sure i might have another problem but for right now im going to change the cat to make sure ...and my question was not really answered ,are those cats going to work... oh yeah dont laugh where is the FPR located and how do i set it.... thanks

 

[markmakeitso]

FPR is at the driver's side end of the fuel rail, it has a vacuum line and a fuel return line heading out of it. Shouldn't really be any setting involved for a stock FPR. There might be a way to test the FPR to see what pressure it opens up at, but I don't know how off-hand.

 

[DrZiplok]

You're running rich.

Chances are that your valve timing is off if you just replaced the head gasket. Check it again.

 

[ILOSE]

it's definetly a fuel issue. On the rich side. But do not allow this to continue as it can melt the cat and completely clog and block off the exhaust.

 

[herostar]

first fix your fuel problem, then cut out the cat and weld in a piece of 2.5" exhaust pipe to match your cat-back

 

[DSMJim]

Originally posted by DrZiplok
You're running rich.

Chances are that your valve timing is off if you just replaced the head gasket. Check it again.

This is bang on. Chances are your ignition is way to far retarded and the fuel and flame front is getting shot right out your exhaust and the cat is finishing the job of combustion, thats why it's so red hot.

Don't say no my timing is fine because 9 times out of 10 it's always timing that is off.

 

[hostile]

His ignition timing is probably off, since he probably moved the cam angle sensor when he took off the head. If the base Ignition timing is correct then you need to recheck your physical timing.

 

[Pennywise]

so by replacing the head gasket you can through your timing off? that makes me fell better might but a 91 awd that has been broken down for about 2 months. he rebuilt the block, got a new head, and replaced all the gaskets. he started the car today and it shook violently, and sounded like a v8/go cart with a crazy cam. is that the timing? I hope so.

 

[honduraneclipse]

Hmmm Ive been reading all your post and thank you for checking up again so far my car has still been running crappy but just a little bit better when i put new gasoline in it... it runs kind of smooth at these speeds 2nd gear 15 -20 mph at 2 grand give or take some and also 3rd gear 27 - 37 mph at 2.5 grand and anything over that it starts to shake again.... i am still confused i am still a new guy trying to learn .... and all these answers you guys are giving me are confusing me... anyways tonight i am putting the car on the lift and putting the new cat on and checking my FPR but i am not sure what the ignition timing is and also the cam angle sensor and also what does it mean to run rich and the ignition timing is way to far retarded thanks for the input i really need this info for tonight

 

[machgsx]

Running rich is basically having a greater amount of fuel compared to oxygen during the combustion process. (Please correct if wrong)

 

[P8ntBalla]

good air fuel mix = [air/fuel]

rich = [air/fuuuueeeeeellllll]
lean = [aaaaiiiiirrrrrrr/fuel]

 

[machgsx]

Originally posted by P8ntBalla
good air fuel mix = [air/fuel]

rich = [air/fuuuueeeeeellllll]
lean = [aaaaiiiiirrrrrrr/fuel]

that's one hell of a way to put it.

 

[jpolizo]

Not to put too fine a point on it, but if you don't know what timing is then the last thing you should be doing is replacing the head gasket. You aren't pulling our legs are you?

Assuming you are serious, the point of all these suggestions is that there is a fairly low probability that replacing the cat is going to do anything for you other than melt another cat. It's likely you have something else wrong. Did you follow the VFAQ, or service manual, for replacing the timing belt when you put everything back together? If not, then I suggest going back over that whole procedure. If the timing checks out properly, then take a look at the fuel system.

 

[honduraneclipse]

Well me and my dad took of that old cat and for sure the cat was clogged up more than a womans bathroom sink and also the ends were burning of the car runs a little better now... it is not shaking like crazy anymore but its definite i still have fuel problems .... guys tell me were to start checking ... and i am not pulling any legs .... i did not replace the head gasket my self a mechanic was teaching me and he was teaching me a few things... i am still learning and i am still trying to figure out how the fuel system works.... any input on how it works and where are all the components located such as vaccum hoses and other things are at.....

 

[umiami80]

No cat is the best cat.

 

[DSM93]

Check your timing on your timing belt and your angle sensor you might be off a tooth or two and causing it to run very advanced.