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-   -   For those of you with boost problems (https://www.rx7club.com/3rd-generation-specific-1993-2002-16/those-you-boost-problems-98645/)

P'cola FD 07-22-02 03:33 PM

For those of you with boost problems
 
I see a lot of questions relating to boost problems lately. So I figured I would give a little preliminary info for those asking questions. A lot of people say "my car doesn't feel as fast as it used to." That isn't very descriptive. So here is how you can help us help you a little easier.
--First off, Get a boost guage. It doesn't have to be anything fancy. Auto parts store have them for less than 40 bucks. Find out what your boost pattern is in third gear.
--Another thing is, if you haven't done the silicone hose job, you might want to go ahead and do it. It's sort of like a right of passage for FD owners.
--If you have low boost on both turbos then you might have a boost leak. I've found that the easiest way to find boost leaks is to take some soda cans or tennis balls or anything of the like, and put them in the intake hoses(from the airbox to the turbos). Clamp the hoses tightly around the cans. Next, get a blower nozzle for an air compressor that can have a vacuum hose slip on. Put the vacuum hose on the blower nozzle at one end and an intake nipple at the other end. Tighten the vacuum hose down with hose clamps at both ends. Turn the car on(not the engine though). Now lightly blow air into the intake with the blower. The air will have no where to go except where the leak is.
--If you have good primary boost, but not good secondary, then your problem could be related to several things: charge control, charge relief, two turbo control solenoids going to the TCA, the precontrol, and possibly a clogged cat (Let me know if I left something off).
--To check for secondary problems, "Tee" into several vacuum lines. To do this, get a three-way vacuum "Tee" and put it between the nipple and the hose which attaches to the nipple, with the other hise going to your boost gauge. "Tee" into the line coming off of the Y-pipe between the secondary compressor and the charge control actuator. It should start making pressure around 3,000 rpm. Above 4,500 and above there should be at least 10 psi at that nipple.
--If there is 10 psi at that nipple all the way to redline, but there is not 10 psi seen at the extension manifold, then you might have a problem with the charge relief valve. "Tee" into that line and see if it is getting vacuum before 4,500 and pressure after. Also make sure that the charge control actuator is seeing the same values.
--It is also important to check the pressure tank and vacuum tank's storage ability. Just pull of a hose going to the pressure tank and listen for air leaving. For the vacuum tank, with the key on, pull off the hose to the CCA. Air should be sucked in.
--If you don't hear your turbos switching over at 4,500 rpm, then you might have a problem with the TCA. There are two nipples on the TCA, one for vacuum, and one for pressure. Make sure they are seeing the appropriate values.
--Finally, don't be afriad to ask. If you give us enough information, we can be pretty helpful. Just be willing to get under your hood (and possibly under your car) and get your handes dirty.
Sorry if this is too long, I just figured I would sit down and do something somewhat helpful.
--Danny

Street King 07-22-02 03:59 PM

Sticky this MOFO, all I see on here are boost problems/leaks, this seems to give a good over view on where to begin.

jdhuegel1 07-22-02 06:37 PM

Good info.

rpm_pwr 07-22-02 07:11 PM

here's a quick secondary troubleshoot guide:

1) Park car turn ignition to on but don't start it:
2) Check charge control is pulled in
3) Check CRV is open ie you can blow through it

if it fails 2 or 3 it's the vaccum storage/switching system. Pull vacuum hose off CRV listen for vacuum chamber filling.

4) leave CRV venting to atmosphere go for drive.
5) floor it in 3rd @ 3500 rpm you should hear the secondary start pushing a LOT of air out by the time you hit 4500rpm
if it fails 5 then :
a) it's the turbo control actuator (did you hear the exhaust pitch change?)
b) it's a major boost leak (this should be very obvious)
c) the precontrol system is not working

6) as you pass 4500 you should hear the venting abruptly stop.
if it fails 6 then it's the solenoids not switching pressure onto the CRV. Block off the CRV and do another run. If there is still no 2ndary boost its the secondary pressure hose that feeds through the LIM into the nest. (green/brown on the wargasm hose diagram)
If you got secondary boost with the CRV blocked then it's the CRV itself (unlikely) or the hose that connects it to the secondary (common).

If you have one of those HKS pods that intentionally put turbulence in the airflow then you're shooting yourself in the foot. They totally mask the sound of all boost leaks.

YayeR 07-22-02 09:14 PM

where is the charge control? and whats the CRV ? sorry if its a dumb question but this is the first car i'm working on, and i'm not getting any response from the secondary when I'm driving.

rpm_pwr 07-22-02 09:39 PM

charge control is at the junction of the y-pipe
CRV is the BOV looking thing

P'cola FD 07-22-02 09:44 PM

Charge control actuator is on the Y-pipe coming off of the secondary turbo. It controls the flapper door in the Y-pipe. The CRV is the charge relief valve. It looks just like the stock blow off valve. It's purpose is to bleed the secondary's boost during precontrol. It is on one of the 1" hoses coming from the side of the Y-pipe.

rpm_pwr 07-22-02 11:35 PM

lol thanks p'cola I had to actually do some work for a moment so I just hit send :)

-pete

legendr35 07-22-02 11:48 PM

I have my CRV venting to the atmospher, but I don't hear any kinda sound coming from it. However I have my ABV venting to the atmospher and I can hear that when I release the accelerator and I can hear it bleeding off boost during partial acceleration. My question is, is my CRV broken? I get decent boost, 10-8-10 but drops to 8 eventually, but look @ my mods, shouldn't I have more boost?

legendr35 07-22-02 11:52 PM

Also, I installed a Dawes devices manual boost controller and had the unit fully open and boost will jump to like 15 + psi of boost!! So I took that off and installed a Joe D manual boost controller and did the same thing, 15+ psi of boost! Is it possible that I installed these units backwards? Will this affect anything? Thank again

rpm_pwr 07-22-02 11:53 PM

dammit if your not prepared to go through the steps how do expect us to help you?

It sounds like your vacuum system is not working. With the car in ignition on with the engine either off or idling, can you blow through the CRV?

If you cant then pull the vacuum hose off the back and listen for the air to rush in.

rpm_pwr 07-22-02 11:55 PM

Yes you're installing them wrong. A manual boost controller should have no effect on boost with the valve fully closed.

-pete

legendr35 07-23-02 12:12 AM


Originally posted by rpm_pwr
dammit if your not prepared to go through the steps how do expect us to help you?

It sounds like your vacuum system is not working. With the car in ignition on with the engine either off or idling, can you blow through the CRV?

If you cant then pull the vacuum hose off the back and listen for the air to rush in.

what if i can blow through it?

rpm_pwr 07-23-02 01:07 AM

you can blow through it but you don't hear anything from it when you floor it from 3000 to 7000? That's pretty impressive. Either
*you have a massive boost leak at the 2ndary turbo outlet
OR
* you have a split 1" hose from the y-pipe to the CRV
OR
* your pre-control AND turbo control are both stuffed

The first 2 should still make a rushing sound and the last is pretty unlikely.

-pete

Cihuuy 07-23-02 07:00 AM

i have a question... does the CRV blows air out if in neutral? coz mine, somehow after i pull the 1" hose dat connects to the air filter, my CRV blows air?? is this normal or is my CRV damaged?

During driving it start releasing air at around 2000rpm and stop at 3000rpm... mine is an auto...

rpm_pwr 07-23-02 07:08 AM

They have FD's in brunei? Wow! You guys get a pretty good mix of cars!

Yes the CRV is open at idle. But it will SUCK air not blow. This is because your secondary turbo is not making positive pressure - far from it!

-pete

P'cola FD 07-23-02 07:24 PM


Originally posted by legendr35
I have my CRV venting to the atmospher, but I don't hear any kinda sound coming from it. However I have my ABV venting to the atmospher and I can hear that when I release the accelerator and I can hear it bleeding off boost during partial acceleration. My question is, is my CRV broken? I get decent boost, 10-8-10 but drops to 8 eventually, but look @ my mods, shouldn't I have more boost?
Often times you can't hear the CRV bleeding boost, because your engine/exhaust is making so much noise. To test if your CRV is working, first hook a boost gauge to the nipple going to it, and see if it gets vacuum before 4,500 and pressure afterwards. If it is seeing proper signals, then pull it off of the car and apply vacuum to the nipple...it should be open(aka you can blow through it). Now apply pressure to the nipple...it should be closed(aka you can't blow through it). Make sure you are checking the charge relief valve, not the air bypass valve. The CRV gets its vacuum/pressure supply from one of the four nipples lined up on the LIM. The ABV gets its vacuum/pressure supply from the nipple on the top of the UIM.

legendr35 07-23-02 07:48 PM

currently, i don't have my crv connected to the air box (using cone filters) you said that it sucks air in? if so, does this mean I need to put a filter at the end of the hose? thanks

spooledUP7 07-23-02 10:55 PM

I have never noticed my crv sucking at idle.

Good info guys.

Cihuuy 07-24-02 09:39 AM

the arrow on the CRV tells us which direction flow is rite.. so isnt it a one way flow??

If the CRV is open at idle then it should be blowing air then?!? not sucking it in... *confused*


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