so recently, i installed a midpipe on my car... the boost was creeping....so i had a restrictor plate made. is has a 2.5 inch opening....just installed it and took the car down the street. my boost didn't creep, but the knock sensor on my PFC hit like 71....i went through my PFC manual and it doesn't really explain what knock is....please give me some help....porfavor, Zach

 

Yikes...

Knock is what kills motors. Knock, or pre-detonation is when fuel is under a critical temp/pressure combo, and ignites without an ignition source. This causes the the combustion to start before the engine cycle is in it's prime timing, causing extreme pressure. In a rotary motor, knocking will cause this "explosion" to happen at the wrong time, and destroy the apex seals that contain the combustion chambers.

In short, knocking is BAD.

Typically high intake temperatures, insufficient tuning, and poor fuel octane lead to knocking.

You may want to rethink your setup, as it sounds like you disturbed the balance of things badly if your motor is detecting that kind of knock.

If your boost was creeping with a higher flowing exhaust, that means that your wastegate cannot keep up with the flow through the turbo's. You may consider porting your wastegate...Or search the 3rd gen section for some more in depth answers.

 

porting the wastegate normally solves it,

 

the thing is, i have 99 spec turbos.....i really don't feel comfortable porting them by myself...another thing though. there is a little cross member directly underneath the mid pipe....its hard to describe, but it runs beneath the exhaust tunnel. the catalytic converter did not touch this because it had the hanger, but when i installed the midpipe, it now touches this crossmember....could that possibly have anything to do with it? the knock only really shoots up under heavy acceleration. other than that, if i stay off the boost it runs fine. i should probablly just put the cat back on....or port the wastegate.....****

 

Well the banging around of the exhaust COULD possibly cause the knock sensor to detect a false knock... I've never heard of that before, but it's not out of the question.

I would see about clearancing that pipe/crossmember any way possible. I would also lay off on driving it really hard until you're sure that you've solved the issue. That kind of knock will destroy that motor really quick if the conditions are right.

 

tomorrow i think i'll try and port the wastegate.....from what i've heard, the hardest thing is pulling the turbos out.....and the wastegate is pretty noticable, i'll paint it and then port the **** out of it.....i think i'll pull off the crossmember too. i'll do that first, take off the crossmember and see if the knock goes away. i just gotta find a dremel......hopefully i won't **** it up

 

your gona need a die grinder and carbide cutting bits to port the wastegate, and take your midpipe and cat into an exhaust shop and have them either cut the hanger off the cat and use it on the midpipe or replicate it on the midpipe, that way youve got a hanger holding it up off that crossmember piece

 

Yeah use the carbide cylinders for the dremel to port the wastegate. The midpipe isn't gonna cause the knock and I knof the brace you speak of, your midpipe just needs a hanger in order for it to clearance then it should be fine. Next time we tell you not to do something, like putting on the midpipe prior to PFC or wastegate porting, you should listen First time teardown seems difficult but after that it becomes easy. Just be sure to clean out the exhaust manifold and turbo housings really well after porting the wastegate. Eliminate all the debris.

 

ahhh...i know tim, it was my fault...lol, i'll listen from now on. i'll have to wait and get the dremel and carbide bits this coming weekend. it's not that the teardown of the turbos is difficult, i just have nothing to go off of. i can't find pics or anything. just something written down on the the sequence of what i need to take off in order to get to the turbos would be nice.. so if anybody knows of any links, or has pictures, send them my way. also, couldn't i put a rag down into the wastegate area to prevent debris from going any further? stupid question, i know

 

It's possible but it's not going to prevent all of it from going in. Mask or plug what you can. Get the FSM (Factory Service Manual) downloaded from the 3rd gen section. It will tell you everything!

 

mmmmmmmm....i like the way u type "everything"......i'm good for the rest of the month...lol..thanks tim

 

to pull your turbos, you pull the intake piping, pull the y pipe off, pull the downpipe, and i think some heat shielding might have to come off to get to the bolts im not sure, but then the turbos just unbolt from the manifold, they are kind of a pain to get out, maybe get a second set of hands to help out, someone below to unbolt them, and pull them off, and someone up top to pull them out from the top

 

oh and theres a a rod that have to unhook from the wastegate flapper thing on the manifold as well,

 

old bad spark plugs is the easiest thing to check for. Put new plugs in and that should solve knock, always does for me

 

heh I just got done pullin out my turbos.

Basically the only other things you need to do in the process is disconnect the oil inlet pipe (use 2 wrenches so bad things don't happen), 2 oil outlet pipes (one on each end of the turbos), and 2 water pipes (one on each end). Disconnect the vac lines from the hard pipes.

Unbolt the 8 or 9 studs/nuts holding the turbos to the manifold and it'll come right off. Most likely the nuts have seized to the studs and they will come out as one piece.

I'd recommend replacing both the water pipes, the oil line orings, the clips for the actuators and buy new studs/nuts unless yours aren't the original ones. The studs and nuts are expensive but from what i've heard it's best to use the oem ones, otherwise you may end up with an exhaust leak from the lack of clamping pressure from the turbos to the manifold. My heat shield bolts were rusted all to hell also so I'll be replacing those on mine too.

Hope that helps.