arr exx seven

Hey, can anyone give me some help? I have a 1986 RX-7, and the power is really restricted. In the low end it works just like it should, but after 4000 RPM, it starts to lack. The higher gear I'm in, the worse it is. I was driving down the highway in 5th and wanted to test it to see if it affected it there, and it stopped rising at 3500 RPM with the hammer down, and top speed was 90 MPH. I know this car can do more than that, and I've never had the engine stop climbing at that low of a rev. Any advice would be helpful.

13bpower

That is a simple one. You have 6 intake ports on your engine. 4 are open all the time. the 2 others open at aprox. 3800 rpms. They are a common problem. If the get stuck closed you will have no power over 4000 rpms.

arr exx seven

thanks, any good way to fix that?

13bpower

Solutions to this problem vary. Ghetto style it, wiring these ports to the open postion all the time. This results in loss of low end power. OR clean them out and make them work properly agian.

Searching this site will provide EXTENSIVE information on this subject. The search button is on the top right section of your screen. ENJOY

jreynish

iTrader: (2)

another possibility is cloged cats, just a suggestion

arr exx seven

Thanks, I think I'll clean them out sometime, if there is anything I know about how my cars, it's that the ghetto style always backfires.

13bpower

GOOD ANSWER! RX-7's need more owners like you.

arr exx seven

Yeah, I heard about the cats being a problem, but I don't really have any on the car right now, just a silencer and a resonator pipe. I guess the easiest way to see if those are clogged is to put the stock stuff back on, since I can do that in less than an hour, but the silencer hasn't been on for more than six months, so I'm hoping that it's not the problem.

13bpower

Oh.... Hold up there a second them.

If you don't have any cats..... that could be the problem.
On 86-88 cars the 5th and 6th ports (as they are generally referred to) operate off of backpressure provided by the cats.

There is a little black hose that goes from your cat to the back passanger side of the block. If that ain't hooked up your ports won't open.

arr exx seven

really? I didn't know that. Well, the problem is a new thing, within the last few weeks, and the new exhaust has been on since August.

jreynish

iTrader: (2)

was this dirrected towards me?
if so thankx cause l8ly all i have been getting from this forum is you don't know cause you only a "kid"

arr exx seven

That hose is hooked up, I have a Racing Beat Exhaust and they made it to replace the stock exhaust exactly, or so I can tell.

13bpower

Calm down, I was talking arr exx, because he said he is not going to ghetto style his car.

Your answer was actually a very good one that I would say would be the second most likely in this situation.

Arr Exx, the RB stuff is good. They should be getting the back pressure they need then.

13bpower

I have heard of random cases where the backpressure from a presilecer/whatnot just isn't enough to activate them.

arr exx seven

Then I guess I'll just clean the ports up. Thanks for the advice. BTW, Jreynish, I understand that ****, I've had to put up with that "just a kid" bs from all of my friends.

rotary>piston

that pipe leading back isnt for backpressure. the backpressure comes from a hole near the manifold. If you take off the manifold there is a hole in the block that allows backpressure to go in and actuate the aux. ports.
You could try just wiring them open, take it for a drive, and see if the high end is there, if not keep looking for a problem.

13bpower

maybe I wasent clear enough. There are 2 hoses/pipes that go back to the cat "area". the big one is to help the cats work properly, the air pump pumps air back there though this pipe/hose. The small one is the one that sense back pressure for the pors and YES, now that I think about it a little more, it conects to the intake manifold.