BoOsTin FD

Ever since i bought my car i had 10-8-8 boost pattern. The turbos were rebuilded before i bought the car (don't know why). The car has 70k now, the turbos maybe 30k.

After i got it, i did sillicone hose job, i replaced all couplers and clamps, i replaced TCA, Tca solenoid (the one on the LIM) Vacuum Chamber and all the check valves. Thinking this will solve my problem.

Nope, still the same. I installed Ball and spring boost controllers for wastegate and precontroller, hoping it could maybe solve my problem. Again, same.

Today i went non-sequential, rikki's style. It took me 40 min. I went for a drive, and frankly i don't like it. For some reason I don't get full boost till between 4 and 5k. IT revs so fast i can't know exact rpm.

However, after it passes 6k it goes back to 9psi and then 8 and holds. Just like it did with sequential.

So i'm asking you guys if you know what the problem could be. I know now that my sequential is ok and all the solenoids as well. What could be the problem then?

Thanks a lot guys

SleepR1

Check out this site for twin sequential trouble shooting http://www.autosportracetech.com/RX-7/rx7stuff.htm

BoOsTin FD

i've seen that site before. No help though.

Thanks

maxpesce

IIRC Mazdas spec for stock boost is nominal 10-8-10 psi but if you read the FSM closely you will see that the boost can drop from 10>8 between 6000 rpm & red line.

When you installed the manual boost controllers did you drill out the nipples on the actuators? Early cars (93) used restrictor pills in the vac/press lines that must be removed to use a manual controller, but on later car the restriction was built into the nipples on the actuators. If you have the restricted nipples then no matter how far you open the manual controllers the nipples will still restrict boost to 10>8psi.

apneablue

Do you have your stock precat? there are a few here that have experienced boost dropping off at high rpm like you are experiencing and it was from a clogged or close to clogged precat. Just a though.

BoOsTin FD

you should see my signature for my mods. I have dp, hi-flo, catback, Intake, etc.

BoOsTin FD

My turbos were replaced, and i have pills in the lines. When i installed my controllers, i did take out the pills. I doubt there should be pills in the lines and in the nipples. I can raise my boost no problem. If i raise it to 12 i get 12-10-11-10 etc.

jdhuegel1

Could this possibly be a wastegate issue? I've been working with BoOsTin FD for quite some time, and no matter WHAT is done, the boost drops till redline. Even increasing boost only results in higher boost for a while before dropping to a 2 or so psi number till redline... Say we run 10. Boost is 10>>>>8....redline. If we were to go to 12 it would be 12>>>>10....redline. Really strange. We've also ruled out the ECU, as the car boosted impropery before the install.

BoOsTin FD

bump

911GT2

How long has the hi-flow been on there? I've heard of some of them going out pretty quick and clogging. I'm by no means an expert, just throwing out suggestions.

Also, have you checked the turbo manifold for cracks?

I'm surprised you don't get full boost in non-seq till that late. I got full boost in the same place with a stock cat and cat-back. It should be much earlier, which leads me to believe that somehow enough air is not getting to the turbos, as in w/a cracked manifold.

BoOsTin FD

I hope they are not cracked. They don't have that many miles on them as the engine. And the cat, I bought from my friend. Air pump has been always hooked up to it, so i doubt it will clog up. I installed it not too long ago, I had same problem with stock cat.

BoOsTin FD

ttt

jdhuegel1

The cat shouldn't be clogged. We actually put the cat on there, hoping the stock one was clogged and we'd get full boost. We got MORE boost, just not full.. Still has the same silly symptoms.

LAracer

You should be able to control the pre- and post-transition boost somewhat independently using the pre-control and wastegate boost controllers. The wastegate valve should control mostly the post-transition while the precontrol valve should control mostly the pre-transition.

With the 12-10-10 settings, can you adjust the pre-control valve to lower the pre-transition boost down closer to 10 (if not, what happens when you adjust the precontrol valve)? This might result in a spike, so the perfect setting might be very hard to find.

Have you already tried this?

jdhuegel1

LAracer,

I haven't been there for all of the tinkering, so I can't be sure if he played with it that much. He has both manual controllers on there. Seems that after transition, or when wired non-sequential (same either way) boost tapers off to redline. Seems to rule out anything with the primary turbo, so we've been working with the secondary.. As you said to look... I believe he tried turning down the precontrol and only resulted in post transition being that much lower to redline also.

BoOsTin FD

If i raise the boost on the precontrol, I don't get no spike or anything. IF i set it to 12 psi, and raise it on the precontrol as well, I get 12-10-11-10 andstays like that, so slight spike right after transition but not at the transition

LAracer

Correct, the precontrol won't affect the secondary much, but it may lower the primary, allowing the secondary to be raised with the wastegate valve.

So adjusting the pre-control valve has no effect other than a little delayed spike?

Don't forget to check the valve-tuning advice on Robinette's site:

http://www.rx7turboturbo.com/robrobi...controller.htm

BoOsTin FD

I'm still runing non-sequential for now. Any input on why i have full boost between 4500 and 5k and not earlier?

fd3virgin

i had a similar problem when i was non-seq....it would lose a little boost when the target boost was reached... checked the couplers and found one with a tiny little hole from tightening the clamp too hard. replace it and the boost holds now at what i set it....just a thought.

fd3virgin

did u check the plastic crossover tube for cracks or anything??? just a suggestion... i am about to replace mine with an efini ypipe..

BoOsTin FD

yeah I checked plastic corssover and all the couplers, they all seem fine.