hey guys,

I have a racingbeat catback and a k&N filter in my 93. I suspect that my pre-cat may be clogged. Will i be able to replace it with a down pipe without having to do anything to increase the fuel input? Will i be running too lean with just those 3 mods? I'd really appreciate your help. THanks guys.

 

if you put the dp on do yourself a favor and go get two needle valves from home depot and use them as your boost controller. on a stock ecu, you don't want the boost exceeding 10 psi. i have the same mods you have but w/ a pettit ecu, and i have the needle valves controlling the boost at 12 psi and they work great. their easy to install and the cost is just about nothing. set them at 10 psi and you should be fine.
nick

 

ok, maybe i'll do that. i just didn't want to have to spend hundreds on an boost controller unit. Is there a certain type of dp i should buy? does any one have any good or bad experience with theirs? and do you know where there are good directions on how to perform the manual boost controller mod? thanks again

 

Here is the Home Depot Racing manual boost controller instructions, he even has Home Depot part numbers listed.
http://www.rx7turboturbo.com/robrobi...controller.htm

 

My Pettit DP was quite easy to install and I didnt have to remove any studs. Good quality unit. Soak the studs the night before with PB Blaster.

 

Yah, second Import's statement about PB blaster. That stuff just MELTS the rust off.

I changed out the DP myself for the Pettit unit. The precat came off in less than two hours. I pulled the studs (easy! But then the turbos were replaced 18K mi ago, so things were a little loose) and replaced them with the ones from Pettit . This allows you to shoehorn the pipe a little easier on installation. The studs on the main-cat were clean enough with the PB that I just bolted the whole thing up.

I will mention that I started the job right after I shut the car off, pulling the intake, ABS shield, etc. By the time I got down to the pre-cat, I could juuuust touch it. The exhaist heat shields were a little difficult to pull warm. Asbestos fingers help Again, PB Blaster lubricated all those nuts and bolts.

I got the pre-cat off while it was STILL WARM about 1hr 45min later. I think the heat may have helped keep things a little expanded, easing the process. Just a thought...

Had to get gaskets from mazdatrix on Sat delivery, so I waited to install. Put the studs in using the pre-cat's original bolts after chasing their threads with a 10mm x 1.5 mm tap. Put one bolt on upside down, another on top, cinch them together, and screw in the stud. UN-cinch them with two wrenches, the bolts come off, the stud stays behind. Nice.

After pulling the pre-cat, I noticed by looking down the o2 sensor hole (don't forget anti-seize when putting this back into the new pipe!) that the cat core had broken from it's hold, and had shifted up and to the rear about an inch or so. Had I continued driving it like that, it would have crumbled and blown hot metal into my main cat, rendering it expensively useless (and I live in WA, where emissions laws are enforced!). SO I juuuust caught it. Whew

It was easy But note that others have had true HORROR sessions with this job. I was prepared to remove the turbos to easy-out broken studs, and oxy-acet the broken main cat studs for replacement with the conveniently supplied bolts. Thankfully, did not have to do this.


Good luck, take your time, and keep motivated by knowing all the heat you won;t have in the engine bay when you are done!!