had my car running pretty good for now. went to store it was fine. left store and got into it some and first was fine second hardly had no boost. and now its hardly anything. it's not the intercooler or piping as i have tried both my front mount volvo one and went back to the factory t bird one with the little couplers still no luck. so it's definately something else. could the wastegate go bad? or the actuator stuck or something? or diaphram broke in it but then it would build unlimited boost right? just don't get it. could the turbo just all of the sudden stop working? nothing appears to be cracked and the wheel looks fine and spins when i take vam hose off? anyone help please
why no boost? turbo experts welcome please
- Thread starter daviddunivan
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Dr_EluSivE
Founding Member
Are your RPM's above 2500 when you are driving, and are you pushing the car hard enough? Turbos will only make boost under load, they will not make boost at part throttle, or at low rpms. Also check your boost gauge, make sure its hooked up as close to the manifold as you can be. As for the turbo, make sure the actuator holds the wastegate tightly closed. If it leaks at all you will get no boost.
Dr.
Dr.
Yup, definately check the wastegate actuator very carefully. That's what comes to my mind first. You might also check to see if the turbo spins freely... I locked up a turbo once, but it was very obvious because I was at full boost when it happen. 
Most other possibilities cause overboost.
Most other possibilities cause overboost.
turbo spins freely and yes full throttle 6500 rpms and only makes max 7 boost now. gets maybe 1lb per 1k rpms happened on third trip out with the volvo fmic setup i just installed. car was running great. 15lbs boost and plenty power. then all of the sudden it would't have much power and hardly no boost. how do i test wastegate and/or how much compressed air do i apply to it to test it. the rod isn't binding and was working fine before. it is tight i cannot wiggle it any. but dunno if it's stuck open or what. no play though
The wastegate actuator has an internal spring to hold the wastegate closed, which builds boost. The natural position is closed. If the wastegate fails, it will normally get a hole in the diaphram, maybe causing an overboost condition. Applying pressure to the actuator would only open the wastegate if everything is working correctly. You could try sucking on a vacuum line connected to the actuator. It should seal. However, not sealing would cause the opposite problem.
You may have to pull the turbo to get a better look at the actuator. There should be at least 1/8" preload of the actuator on the arm. Though it feels secure, there may be some play on the arm. Other causes could be boost leaks after the turbo or huge exhaust leaks. Are you using a VAM or other air meter?
You may have to pull the turbo to get a better look at the actuator. There should be at least 1/8" preload of the actuator on the arm. Though it feels secure, there may be some play on the arm. Other causes could be boost leaks after the turbo or huge exhaust leaks. Are you using a VAM or other air meter?
Dr_EluSivE
Founding Member
What form of boost controller are you using? Also if i remember right, the clocking of the turbo shouldn't really affect the waste gate arm. Is it at some weird angle? It should be practically straight
Dr.
Dr.
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