ALPINE

What are the indications of burnt valves short of taking a look at them? I've been running cats only for a month or so and it dawned on me...

ss rally red

iTrader: (8)

Put this on the"only worry about if you've got nothing to worry about list" has the performance changed any?

ALPINE

Heck yeah, it pops after about 5k, bad power loss, falls on its face. Sounds like its running lean or something, almost a back fire.. I'm not really sure whats happening up there, its pulls hard as normal till then.

P Mack

iTrader: (6)

Compression will be low in that cylinder if you have a burned valve. I doubt you have a burned valve but at least it's easy to do a compression test.

Tim 98z

iTrader: (1)

Many of us have been running basically wide open exhaust for a LONG time. I know on my car since it's a "race" car i dont even run cats and only bullit mufflers (no back pressure) on a dual 3" X-pipe setup for quite some time. No burnt valves here. For some reason i doubt that is your problem. But i'm no pro just my opinion.

BadAndy

Hey Ken, I guess that will go on my list of stupid **** I will probably worry about.

ALPINE

Thanks, hopefully it's just a tuning problem..

Tin Indian

I agree with everyone else. I hardly doubt that you have "burned valves".

What gave you this idea anyway?

Do a compression check if you are really worried about it. After you find the compression is ok on all cylinders, look elsewhere for your problem. I would start with a loose plug wire.

If it's a fairly high mileage car, change out the fuel filter too (but I doubt that is your problem)

ALPINE

My engine falling on its face at 5k soon after i took the pipes off is what gave me the idea. But, I'll check elsewhere.

soundengineer

iTrader: (16)

burnt valves usually come from running too lean too long....sounds like a timing issue....maybe your cats are getting clogged...If you have been running rich for a long time it would clog up the cats.....especially if you pulled out the air pump stuff...did you???

ALPINE

All I'm running is cats, with AIR system... that's about to go. I'm about to do LT's cam and n02 so, I'll handle the tuning problem then, if that's what it is.

soundengineer

iTrader: (16)

sound more like clogged cats.....not enough exhaust getting out...loads up the motor...feels like it has no power and it gonna blow up or something????

ALPINE

I'll take the cats of tomorrow, what all do I need to do this, what's the nut size are the bolts on the cats themselfs?} That's all that's all that's on there anyway.

soundengineer

iTrader: (16)

bolts are seperate...on studs on the manifold...they can be a bitch to get off...use a torch to get them really F-ing hot and they'll break loose easier(trick of the muffler shops)....takes a 15mm??? or 5/8 or something like that....you'll need a long *** extension....If they are clogged...you can poke a hole thru 'em(or gut 'em) till you can get it taken care of....or just stay low in the rpm for a while...just dont get in trouble with the polution police..big fine$$$

ALPINE

Alright, I'll try that tomorrow. I'll get back to ya.

Assassin

iTrader: (3)

dead at higher rpm, I'd say cats, wont let exhaust past, I've been itching to kill my cats as soon as I get the o2 sims, cant wait to hear the sound w/Hooker shortys and straight pipe!

ALPINE

crewdawg16

I had a 3rd Gen TPI, it's cat got clogged so bad that it wouldn't stay running. But when it first started, it is exactly as you described. It goes good until a certain rpm and then, nothing. I could actually put the car in park and smash the gas pedal and it would stop at 4,000 rpm and stay there. The car was never the same after that.

ALPINE

eek

Cal

iTrader: (1)

My 3rd Gen would only go 35 mph with it's cat clogged. I gutted it and put it back on, and the car had more power than it did when it was new! (150,000 miles)