---------------------------------------------
It will be hard to understand this unless you understand the sequential boost system on a 3rd gen RX-7. Check this for a quick explanation.
Here's the boost pattern I get at WOT in 3rd (TEST 1)
0-5500 rpm: boost steadily decreasing from 13psi to 10psi
5500 rpm: 5 psi
5500 rpm-redline: 6psi
----------------------------------------------
Tests I've run to diagnose the problem
-----------------------------------------------
I T'd into the nipple that is on the back of the Y-pipe just behind the Charge Relief Valve's (CRV) hose connected to the Y-pipe
Apparently, what I should see is:
(3rd gear - WOT)
0 - 4000 RPM: 0psi
4000 - 4500 RPM: Roll up to 8 psi +-1psi
4500+ RPM: 12psi
but what I saw was: (TEST 2)
0 - 5200 RPM: 0psi
5200+ RPM: 7psi
This suggests that the secondary is not being prespooled
----------------------------------------------
I T'd into the side of the pre-control solenoid that goes to the actuator. Here's what I saw at WOT in 3rd (TEST 3)
0-3000rpm: 0psi
3000- ~5000rpm: rising to 2.5psi
>5000rpm: pressure falling to 0psi
----------------------------------------------
I T'd into the hose that connects the precontrol solenoid to the precontrol actuator (on the solenoid side) and also to the short hose that connects the actuator to the y-pipe. The first test was a repeat of the one I talked about before where I got 2.5psi. I got the same this time. The second test (TEST 4) was different. I got over 10psi at around 4000rpm (easily enough to open the precontrol valve). This test is about as close to the actuator as you can get. Conclusion: the precontrol IS working.
----------------------------------------------
Ok, the first thing I checked last night was the charge control actuator. The shop manual says it should move with 1.9inHg applied. I had to apply 5inHg to get it to move all the way, so maybe it's a little sticky. I need to T into that line while driving and see what the pressure is; maybe this difference is insignificant.
Next thing I checked was the charge relief valve - works perfectly, tested it exactly as the shop manual said. I even tested it again using the hose it connects to in the rats nest to rule out a leak between there and the valve.
I also checked the charge relief solenoid. It works fine.
The vacuum system is fine. I hooked a vacuum pump to the hose on the front side of the check valve and the system held 15inHg steady for over 5 minutes. I also checked the check valve.
I checked the TCA by hooking a pump to it's hose in the rats nest. It worked fine (watched it move from under the car when the pressure was released). I think the only actuator I have not yet checked is the wastegate.
----------------------------------------------
T-ing into the line between the charge relief solenoid and charge relief valve (CRV): (TEST 5)
<3500rpm: 15"Hg (valve is open)
between 3500 and 5200rpm: 0psi (valve is closed)
>5200rpm: 7psi (valve is still closed)
(I just now double-checked this result by T-ing into the vaccum hose right at the CRV)
----------------------------------------------
T-ing into the pressure line between the turbo control solenoid and the turbo control actuator (TCA) (TEST 6)
<5000rpm: 0psi (valve is closed)
>5000rpm: 6.5psi (valve is open maybe - I haven't checked the vacuum side yet)
----------------------------------------------
T-ing into the vacuum hose right on the charge control valve (CCV). Here's what I got: (TEST 7)
<5200rpm: 10"Hg (valve is definitely closed)
>5200rpm: 7.5psi (valve is definitely open)
So the CCV appears to be working fine.
----------------------------------------------
Removed CRV, just to see the effect on prespool. Since the T-test on the CRV (above) shows the CRV closing after 3500rpm, I thought maybe that was affecting my prespool. After removing the CRV, there was still no prespool, as measured in the secondary side of the y-pipe (still 0psi to 5200rpm then 7psi).
Current Theory and Resolution
In my thread at nopistons.com ((http://www.nopistons.com/forums/index.php?act=ST&f=10&t=9291&s=10052c0041f6b1dbeda47829ffb11df9)
Tom93R1 suggested that my boost problem was caused by the high altitude (7000ft) I live at, Thus, I installed "home depot boost controllers" in place of the precontrol and wastegate pills. After some adjustment of these new valves I managed to get very close to a 10-8-10 boost pattern, although transition still occurs at 5500 instead of 4500rpm. I'll continue to attribute this to altitude until I learn differently.
If you have any comments on my problem then email me or add a post here.
back to main page