here i was thinkin my car is in great running order....and then i install my boost gauge. 6lbs of boost! the good side to that is 6lbs feels fast, i wonder what 10 will be like. but anyways, i just got smoked tonight by a stinkin vtec prelude! he runs like mid 14s and he smoked me.

my boost in 1st in 6 pretty much to redline, then 2nd it is 6 till about 5000rpm then drops to 4, and in 3rd it is 6 till 4500 and then drops to 4 and by redline it is at 3. i dunno where to start looking, can anyone help me? i have a video of my boost gauge going from 40 mph to 80mph showing my boost pattern. ill try to get it up if i can find a place to put it.

 

Since you never get over 6 psi, it is not an issue with your second turbo coming online. It could be a boost leak, or it could be a wastegate problem. Check all your intake tubing for cracks and make sure the connections are tight. Do you hear any leaking air noises under boost? Also, check the vacuum hoses for your wastegate control. I'm not sure which ones they are, but just look at the vacuum diagram and it should be obvious.

Good luck.

 

I agree with paw140 it's most probably your wastgate. definitely check your wastgate vac hoses.

 

if anymore info is needed...i watched the video


punch it at 40mph in 3rd gear, 6 lbs instantly

50mph - 6 lbs
60mph - quick drop to 5 lbs
70mph - 4 lbs
80mph - 4 lbs
shut it down

it starts shaking too...i used to be able to hit 110 in 3rd like nothin, now i struggle to hit redline. still think its the wastegate?

 

you might need knew turbos.
also get a compression check.

 

what kinda vaccum are you pulling at idle and what kinda exhaust system do you have? perhpas both your cats are clogged or soemthing.

 

Well it was asked before but I will ask again, do you hear loud air leaking noises when under boost? I would suggest looking at the coupler that the y-pipe uses since that is a known boost killer. It may look ok but take it off the car and take a better look at is, cracks are hard to see when there is no air being compressed through those couplers.

 

well its a new motor, ~3000 miles on it. the turbos are original. the exhaust is an HKS downpipe with a gutted stock cat...and then the stock catback after that. is there any way to test for boost leaks without driving the car? its snowin like a mother here but i'm determined to get this fixed. i was planning on going sequential one of these days anyways...would that perhaps fix it? well i guess not if its a boost leak, i first have to check for that

 

You were planning on going sequential huh?? You already are, perhaps you mean NON-sequential? As far as checking for boost leaks without driving the car, sure you can, check all your hoses and couplers for starters.

 

the exaust also a good point. I know a guy who replced
his clutch because he felt his rx-7 "slipping" and loosing
power in hi and low revs when in fact he needed a knew exaust. which salved the problem.

 

It could be any of the things mentioned, but the magic number 6 is suspicious. That is approximately the amount of boost you'll get with wastegate spring pressure only. In other words, if you remove the ECU from the equation, the uninterrupted pressure on the wastegate actuator will give you 6-7 lbs of boost, no more.
This makes me think the duty solenoid the ECU uses to control boost is broken, disconnected from the ECU, or is otherwise out of the picture. However, the easiest thing to check is your various couplers between the turbos and the intercooler, and between the intercooler and throttle body. You can get a split in one of those that you don't even notice visually, but once you start getting pressurized air through there it will open up and vent your boost. That has happened to me on several occassions, although it usually limits me to less than you're getting when it happens to me.

jds

 

I had a split in my lower IC coupler awhile back, before my FMIC and I was getting 5.5-6psi only so I would definitely look there, plus you couldnt really hear the air "rushing" noice like you could when I had a split on my y-pipe coupler. Let us know how your couplers look!

 

Yeah 6 psi on the primaries should indicate a boost leak. Usually the Second turbo will not come online unless the primary reaches 8 psi.

 

Like OneBadRx7 said, check the y-pipe coupling. That's a common problem. If it's not that, start testing the vaccum hoses, solenoids, check valves, and actuators. The wastegate seems a good place to start, based on other advice in this thread. Here's the boost system troubleshooting place...

http://www.autosportracetech.com/RX-7/rx7stuff.htm

 

I would check for boost leaks first and then the main cat. Since your boost is dropping at high rpm (as it should) I think the acuators and solenoids are working correctly.

I had an odd problem at the track recently. While lapping the boost started to degrade from 11psi over a period of about 10 minutes to only 7 psi. The 7 psi caught my eye as well and I spent an entire afternoon troubleshooting the wastegate actuator. No problems there. Checked the entire solenoid rack, no problems there either. Finally I pulled the main cat and dumped out a large wad of steel mesh and a couple handfuls of a disintegrated brick. Bingo!

Apparently the cat actually failed before my eyes while I was lapping. Now with a new (used) cat the car pulls noticeably harder at high rpm than it ever has; apparently my old cat was at least slightly clogged the entire time I have owned the car.

 

i have no cats on my car...the precat is replace with the HKS downpipe, and the main cat has been gutted. i will definately check the intercooler couplers. is it fairly easy to tell that they're split, after you remove them?

 

Also check the check valve coming from the pressure tank. If it is installed backwards or is not properly functioning it will not let the pressure tank hold pressure. This will keep your wategate solenoid from functioning properly.

 

were you able to check it out yet? once you remove the ic piping and take the rubber coupling off all you have to do is just bend it and look for cracks in it. it takes like 10 min's at the most to check it out. let us know when you check it.
nick

 

i was haveing a problem like that and I went non-seq and it fixed the problem now my cat is clogged and i get 7 to 8 psi

i got a MP, cat and DP getting put on sat hopefully it will fix it, i have a brand new reman with 3k on it so it might be the same thing

 

vac is ~15 or ~16 at idle...idle is 1100~1200

 

why tell us this, check your couplings and IC hoses FIRST, then come back and let us know if those are all ok first then we can try to help you out in a different direction.

SD

 

sorry, just wanted to put that in while i was out checkin the hoses.

anyways....checked the couplings and IC hoses, couldnt find any cracks or anythin. checked all vac hoses i could visibly see, and followed the ones down to the wastegate control and all the ones to the turbos. everything is hooked up. the only thing i saw was a blue connection type thing next to the wastegate control and turbo precontrol. other than that everything was ok.

the only thing that i did no do was pull off the Y pipe, cause it looked like it needs gaskets and stuff to put it back on.

i did take it for a ride after putting all the hoses back on and all that, and now i can pull 8-7-8 pattern at best, usually 7-6-7 but it holds the boost to redline, no more dropping off to 4.

 

check for pills....i had 7 across the board and it was because the maztechs that did my car befroe i bought it put the lines on with no pills in them

i.e., pull off the hoses coming from the main (front) turbo going to the two actuators, make sure they have a pill inside the hose