Is my main cat clogged??
 

I have a boost problem that was 10-8-10 but now the boost is 8-5-8. Funny part is the car is not fully warmed up i can get 10 lbs but once its fully hot then is 8 lbs. I was told that a clogged main cat can do that is this true? I have 80,000 mile on it and i took off the pre-cat long time ago. what are the signs of a clogged cat? thanks

sounds like a 5 min test on your part could answer this question. unbolt the main cat and see what happens. if boost presure is raised, you figured out your problem. place a bolt inbetween the studs to leave an opening in the exhaust before the cat. :D

That is a terrible solution. First of all, even with a brand new stock cat, you are going to see more boost when you disconnect it.

If your boost dropped all the sudden, it could very easily be a small boost leak. The coupler between the cross-over tube and the IC slipped a fraction of an inch out from the clamp during a dyno run and my boost dropped down to below 7 psi (only made 175 rwhp on that run!). It doesn't take much.

so this leak he is describing is one of those magical ones that seals itsef up while motor is cold?

i have the exact same problem!!! i get full boost when the the car is getting warm... but when it's fully warmd up, boost dropd... Damn, it feels slow now... :( i gutted my main cat so its not the cat then... any inputs?

There's no need to be smart ass. And YES, some problems aren't noticeable until the car is fully warmed up. Although this would usually be associated with solenoids sticking or something of that nature.

To be honest, I don't have much more of an answer for him. I just mainly pointing out the flaws of your suggestion regarding disconnecting the cat.

if he has a boost leak in the intake, he will not see much more boost by placing a bolt inbetween the cat and DP to open it up a crack. so...yes this is one way to test it.

we could also tell him to build a pressure tester for about $10 at home depot. but i was starting off where he (the person who drives the car and has an idea of what is wrong with the car) felt the problem was. then move on to the next thing.
a boost leak will not matter what temp the car is running. it is a HOLE in a hose. :)

Yeah it can. Not only can temp matter, but other factors can as well. I just fixed a leak that would boost like crap doing city driving and a lot better on the highway...when it was warmed up. It would boost better in the city when cold. Rubber is funny that way as it's more stiff when cold than warm. It depends on the severity and location of the leak. He could be experiencing a similar problem. They were the 2 stock rubber couplings between the IC inlet and back. Not saying that this is it, but you never know.

thanks for all the help guys. I checked all my clamps and hoses and didnt see a leak. Are cracks in the hoses very hard to see? How do i check if a solenoid is bad? just to let you guys know i had a shop tie-wrap my vaccuum lines already. thanks guy for your input

why are you guys boosting while your car isn't fully warmed up anyways?

this happened to me last month
what happen was everytime that I gun my car, it would boost right the first time. But if I boost right after that, it tries so hard to even reach 5psi. It turned out to be the primary inlet hose have a hole right next to the smog pump belt. What's weird is that the belt is at least an inch away from that hose, so apparently the engine moves as I WOT my car. I've also replaced all the stock couplers with silicone ones, which somehow gave my car better turbo response. I recommend everyone to do this since it only costs $20 for the couplers and clamps.