MattRX7

I've been having an intermittent boost problem for a while now. My only mod is a downpipe.

When I first start driving, the most I can hit is 8psi on my primary. Eventually, however, I start hitting 10. At first, it would only take a few minutes to start hitting 10. Now it can take up to half an hour or longer. Sometimes I never see 10psi. So I've been seeing a lot more 8psi than 10psi as time goes by.

Any ideas? Why would it max out at 8psi for a while, and be able to do 10psi later?

Thanks,
Matt

FDjunkie

Assume you’ve already checked all the vacuum lines and turbo plumbing, so a wild guess is a leaking or sticking control valve that starts working better after the engine heats up. The list of possible suspects is as long as your arm. Recommend that you check out the troubleshooting section of the following web site for information of operation and testing procedures.

www.autosportracetech.com/RX-7/rx7stuff.htm

FYI. Saw a post by another member here on the forum where he systematically moved a vacuum/pressure gauge connection around to each area of the turbo control system so that he could temporarily watch the circuit’s operation while he drove his car around. It allowed him to successfully track down his INTERMITENT gremlins and sounded like a really wise approach.

nmo93

matt,
i think the double throttle can be the cause of your problems. when the car is cold the double throttle prevents you from boosting the car to 10 lbs. so that will explain why when you first get in the car you are not seeing the full 10lbs. but once the car warms up you should be able to see full boost.
now since you say sometimes it takes a half hour for you to see 10lbs, i think that sometimes the double throttle is getting stuck and not opening all the way. check this link out on how to disable it and for more information:
http://www.rx7turboturbo.com/robrobi...e_throttle.htm
nick