speeddemon7

Ok so ive been trying to catch this gremlin that ive been having for quite some time.With very little to no luck.

Symptoms.I get primary boost with no problems.10 psi.
Once the transition occurs boost seems to fall off and doesnt want to build back up again.It seems as if some valve is refusing to open up and let the turbos spool up properly.When this happens the turbos themselves sound like they are struggleing to spool up.The really strange thing is that if I let off the throttle while all of this is happening I get a very audible booooouuu sound where my blow off valve sound is supposed to sound.
I have noticed that the car only does this at transition
and when it warms up.This morning I started the car up and it ran very strong.No transition problems.Once it warmed up enough I started to get the transition problem.What underhood components are affected by heat pertaining to the twin turbos controll system?
If anyone has any info on possibly symplyfying the system id also appreciate it.Thanx.

RX7Wishing

first... you shouldnt be running it hard on a cold engine. ( im sure you know because you have 500+ posts )

Second. i had the same problem. when my car was at Normal Op temp it would run fine. but after a few hard runs... it fell on its face and boost was slow to build and it didnt build all the way back up.

Solution to MY problem = I added a 3 Inch DP. Problem is now gone. Im guess as soon as the pre cat got really hot from a few hard runs. It started to not flow to well.

speeddemon7

what about this really retarted sound im getting from the car? Also one thing I have noticed is that if i let the car rev down I can get the car to boost correctly again.Very weird problem.I swear it feels as if something gets stuck once the transition takes place.
Im thinking tca but then why would it only do it when the car is warmed up.Can the turbos control actuator go bad? Also correct me if im wrong but the tca only controlls secondary boost right?

speeddemon7

about the precat.did you get these symptoms in primary and seondary boost? or was it just at transition? my problem only comes into play once the transition is supposed to occur.Before that the car runs fine.

DeaconFrost

sounds like you dont have enough vacuum to operate one of the solenoids...hence why when you let it rev down...it gets plenty of vacuum and then works fine...there might be a leak somewhere or a solenoid on its way to the crapper.

thats how I thought of it anyways...my car does that sometimes...well used to.

alwan16

check for boost leaks, a bad charge relief valve, or even a solenoid that might be intermittent once the engine warms up. it's going to take a bit of detective work at this point....

speeddemon7

The crv was swapped out with the air bypass valve.Didnt fix the problem.
all the rats nest solenoids were replaced about 6 months ago with new ones.So Im not sure at this point if they went out again.
Im really thinking of doing the vacuum hose symplification if only to reduce the number of possible problem areas.Anyone have a link to a do it yourselfer?

speeddemon7

ok a slight development.I jacked up the car and actually inspected the tca actuator and rod assembly.To my surprise I found that the rod is barely on the swivel assembly because the c clip is missing. I dont think this is the cause of my problems.But then again who knows.Maybe it is.
Where can I get the right size c clip from?
Ive got an autozone and a checkers right by my house.Will they have any?

mad_7tist

it is an e clip actually good luck finding one you will most likely have to bend a c clip to fit

speeddemon7

still no dice.I found e clips at autozone and put one on.
The car is still having problems.I wonder if anyone else has had these same symptoms.Especially the booooo sound the car makes when its supposed to let off pressure through the blow off valve.

r1owner

IF you're getting boost when its cold, but not once the car gets hot, it could be the solenoid that's attached to the air control valve. There was a post somewhere where the dude actually took that off, tested it (worked fine when at ambient). Put it in his oven at like 175 and then it didn't work.

Cameron

Hi
New to this site. I have a very simlar prob with my 96 RX7. I brought it with (need turbo relaced) I have relaced the turbos with reconed ones. Second turbo still wont boost. At 4500revs it drops to 5 pound then decreases. If I put my foot on the gas while above that I usually get 1or 2 pound and thats it. I also get that sound when the car dosent boost (like an internal blowoff valve)??? I have checked all the piping for leaks. I have have pulled the plugs off the solinoids and get a constant 6 pound(as I was told u are supose to???) What I have noticed is that I don't get a hiss on of air when i pull the air hose off the pressure box(that black box on top of engine) A friends 7 gets a hiss. Dont know what this means.
The vlave that controls the butterfly that allows the second turbo to boost(whats it called??) Could it be that? How would you check it?
Hope one of us works this out - its getting frustrating

Cheers

speeddemon7

yeah i hope I can figure this out as well.Its becoming very frustrating.I guess now im not the only one that has this problem.
ahh you mean the turbo control solenoid.It figures it would be the only solenoid that I havent replaced with a new one.

r1owner

I've got a similar problem, but mine has no boost at all at 4500. Just stopped working all of a sudden one night at the drag strip.

I am doing the vacuum hose job right now.

SBi_Owner

Ok, I think you need to focus your attention to the pressure tank and the vaccume tank. The pressure tank is on top of the engine and the vaccume tank is behind the power steering pump.

First, get a vaccume pump from the autoparts store and do a vaccume test on both tanks to 15inHg. The next step is to do the same test to the 3 check valves visable right below the UIM. If these tanks and valves fail due to heat, there will be no pressure or vaccume to opperate the sel. valves. This might explain the need to let off the gas, fall into vaccume and then the secondary will spool up. I would start there and then let us know what you find.

Cameron

I'll do the tests. I think that the boost I am getting after 4500 rev is the first turbo still boosting. Don't think I get anything from the second. Thanks

speeddemon7

my condition seems to have changed a little bit.Because now once whatever sticks or doesnt operate stays that way.Whether or not I let the car rev down.I already checked the pressure tank and the vacuum chamber.
I will check the check valves as well.

teachermechanic

iTrader: (4)

Hi, pass 2 year i had the same problem.
If you have the workshop manuel go to page F-119.
Is the item #1 (turbo control solenoid valve).
Remove with 10mm socket and check with hairdrier and 12v batterie.

fd3s_rx7

iTrader: (13)

mine was the turbos itselves...

speeddemon7

I dont think its the actual second turbo as it sometimes works without a hitch.Its a intermittent problem.But Im starting to think that the turbo control solenoid is at fault.Mainly because its attached to the acv.I also had to remove it to get the acv off the lim and its the only solenoid that isnt new.
Heres some more information on my problem.Car works fine up to transition.Once it hits 4500 rpm's the boost takes a nosedive and seems to be limited to .2 bar or 3 psi and no higher.No matter how hard I push on the gas.Maybe my wastegate is sticking open.
I also noticed something very strange.This happenes very rarely but it may be a clue as to what the problem is.I was gunning it and past transition the boost was still there for a few seconds.Then I heard this flutering that sounded like a valve opening and closing repeatedly.At the same time this was happening the needle on the boost gauge was clibing and falling repeatedly.What causes this?
and of course after that it finally settled back down and wouldnt go past 3 psi.

mad_7tist

have you checked the crv

SBi_Owner

OK, here is another point to read, it might help more with diagrams.

http://www.autosportracetech.com/RX-...leshooting.htm

I know a few more if you need.

speeddemon7

Ive swapped out the crv with the air bypass valve and still no success.Ive checked the check valves.One question though.The check valves are supposed to be checked with pressure right? Instead of vacuum.I used a mityvac.When it comes to pressure they work great.When it comes to vacuum they slowly leak.Meaning the gauge slowly goes down.I got the same exact results from all of them so I wouldnt think that any of them are bad.Since they all operated the same.
I could use a few more websites as ive already been using the auto sport tech one for some time.

speeddemon7

Ive swapped out the crv with the air bypass valve and still no success.Ive checked the check valves.One question though.The check valves are supposed to be checked with pressure right? Instead of vacuum.I used a mityvac.When it comes to pressure they work great.When it comes to vacuum they slowly leak.Meaning the gauge slowly goes down.I got the same exact results from all of them so I wouldnt think that any of them are bad.Since they all operated the same.
I could use a few more websites as ive already been using the auto sport tech one for some time.

speeddemon7

im thinking that the charge control actuator is not getting its vacuum or that the ccv valve is getting stuck.Probably because of vacuum issues.
If anyone has a good info site as far as testing this specific system id really appreciate it.