I'm surrendering to the forum- No boost issue
09-21-18, 11:30 AM
#1
I'm surrendering to the forum- No boost issue
I'm out of ideas and near out of patience. I have a 93 with 85k on it and stock twins. It doesn't make boost. I have researched and looked on the forum. Plenty of guys saying they can make boost until 4500 rpm or after but I haven't found much saying no boost at all.
Power fc, Pettit cat, cattless downpipe and Sard intakes on the car. Car runs and idles fine bur a mechanical boost gauge and the commander for the Power fc confirm that no boost is being made. Under acceleration you can hear turbos spooling and you can hear blow valves opening when the gas it let off. I have done a smoke test to look for boost leaks. Two minor leaks were found and repaired. I have checked functionality of the wastegate and the blow off valves. Everything appears to be in working order.
Who has some ideas of what's going on with this car?
Power fc, Pettit cat, cattless downpipe and Sard intakes on the car. Car runs and idles fine bur a mechanical boost gauge and the commander for the Power fc confirm that no boost is being made. Under acceleration you can hear turbos spooling and you can hear blow valves opening when the gas it let off. I have done a smoke test to look for boost leaks. Two minor leaks were found and repaired. I have checked functionality of the wastegate and the blow off valves. Everything appears to be in working order.
Who has some ideas of what's going on with this car?
09-21-18, 03:23 PM
#7
https://www.rx7club.com/3rd-generati...-stuff-802060/
See post 15
And as Narfle mentioned, check all rubber post turbos and pre TB
See post 15
And as Narfle mentioned, check all rubber post turbos and pre TB
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09-21-18, 06:20 PM
#8
it would have to be quite the huge/noticeable leak if you’re getting zero boost. i have had a 0 boost situation before.
one thing that could be happening is that the charge control valve, the one in the pipe just behind (and connected to) the y pipe is staying open instead of only opening after transition. all of that boost will be expelled out the charge relief valve if that’s the case.
you shiuld be able to test to see if that is where your boost is escaping by just blocking it off. plug the end of the hose that’s facing the front of the car connected to the charge relief valve (that’s the one towards the back) and plug whatever it was attached to, and see if you make some boost then.
one thing that could be happening is that the charge control valve, the one in the pipe just behind (and connected to) the y pipe is staying open instead of only opening after transition. all of that boost will be expelled out the charge relief valve if that’s the case.
you shiuld be able to test to see if that is where your boost is escaping by just blocking it off. plug the end of the hose that’s facing the front of the car connected to the charge relief valve (that’s the one towards the back) and plug whatever it was attached to, and see if you make some boost then.
09-21-18, 07:18 PM
#11
it would have to be quite the huge/noticeable leak if you’re getting zero boost. i have had a 0 boost situation before.
one thing that could be happening is that the charge control valve, the one in the pipe just behind (and connected to) the y pipe is staying open instead of only opening after transition. all of that boost will be expelled out the charge relief valve if that’s the case.
you shiuld be able to test to see if that is where your boost is escaping by just blocking it off. plug the end of the hose that’s facing the front of the car connected to the charge relief valve (that’s the one towards the back) and plug whatever it was attached to, and see if you make some boost then.
one thing that could be happening is that the charge control valve, the one in the pipe just behind (and connected to) the y pipe is staying open instead of only opening after transition. all of that boost will be expelled out the charge relief valve if that’s the case.
you shiuld be able to test to see if that is where your boost is escaping by just blocking it off. plug the end of the hose that’s facing the front of the car connected to the charge relief valve (that’s the one towards the back) and plug whatever it was attached to, and see if you make some boost then.
How to test solenoids will be helpful. As I mentioned all connections appear to be good, i.e. no leaks, and bov and crv are holding pressure. It doesn't appear that boost is escaping. Maybe it just isn't being controlled properly by the wastegate even though it is functioning or maybe the one or more of the solenoids isn't functioning properly.
09-21-18, 11:45 PM
#15
How to test solenoids will be helpful. As I mentioned all connections appear to be good, i.e. no leaks, and bov and crv are holding pressure. It doesn't appear that boost is escaping. Maybe it just isn't being controlled properly by the wastegate even though it is functioning or maybe the one or more of the solenoids isn't functioning properly.
still, another way to kind of test this to block off the charge relief valve so nothing can escape. it’s not that that valve is leaking, it’s that your ecu is telling that valve to always be open before transition.
you mentioned it sounds like the turbos are spoiling and creating boost, and you hear the bov right?
another thing to check is the preload in your wastegate actuators. not sure if you can adjust both on stock turbos, but i think you can at least adjust one of them. look up which one is the pre control, and make sure the arm is taut, and not loose.
sorry, i can try to help more when i’m at a pc. if you message me on face book (search wutangben) I can help over messages.
09-22-18, 06:20 AM
#16
First focus on the primary boost, then the secondary, then the transition. The transition will be junk without primary boost.
No primary is from:
A big leak (visual inspection or pressure test)
Collapsed primary intake tube (inspect)
Blocked air intake (inspect)
Failing charge control valve CCV, or it's actuator. (follow FSM tests, tap vacuum line line with a boost / vacuum gauge and verify the solenoid is sending vacuum then boost)
Stuck open TCA (inspect)
Be patient... Debugging turbo issues on these cars is not easy.
No primary is from:
A big leak (visual inspection or pressure test)
Collapsed primary intake tube (inspect)
Blocked air intake (inspect)
Failing charge control valve CCV, or it's actuator. (follow FSM tests, tap vacuum line line with a boost / vacuum gauge and verify the solenoid is sending vacuum then boost)
Stuck open TCA (inspect)
Be patient... Debugging turbo issues on these cars is not easy.
The following 2 users liked this post by djseven:
FourtyOunce (09-24-18),
gmonsen (09-25-18)
10-25-18, 12:22 AM
#19
This is usually when i throw my hands up in the air and bring it to a local rotary expert. Could be anyone one of the vacuum lines or solenoids. (True story 2 months ago same thing happened to me, turns out it was one of the solenoids, would have never found the issue on my own)
10-29-18, 08:35 AM
#21
RX-7 Bad Ass
iTrader: (55)
The WG actuator arm being disconnected will do the trick. Even with all the vacuum lines hooked up wrong, the turbos should still build primary boost unless there's a boost leak or the wastegate is open.
Dale
Dale
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