charliegt

Recently I've noticed that my boost pattern is 10-8-10 but then quickly drops to between 7-8 for the secondary turbo. Today the secondary turbo didn't even seem like it was kicking in, then later in the day it was working perfect 10-8-10. I'm not sure what could be causing this so I figured I check and see if anyone has some ideas.

My engine mods include a downpipe and a greddy SP catback.

I am pretty sure that either my FPR or FPR control solenoid is going out due to occasional hard starts when hot, and rough idle for the first 30 seconds after startup (only happens sometimes). I've noticed when its running poorly right after startup that the a/f gauge is showing all the way lean, and then slowly moves to stoich/rich after about 20-30 seconds. I don't know if this could have something to do with it or not.

Let me know what you guys think.

Thanks,
-Charlie

maxcooper

It is somewhat normal for boost to drop off toward redline. 10-8-10-8 might be a more accurate description of the normal boost pattern. However, it sounds like you are getting inconsistent results, which may indicate some kind of issue.

The FPR solenoid is said to prevent the FPR from seeing vaccum on hot starts. I could never figure out quite why it was desgined to do this, but I suspect the solenoid has nothing to do with your hot starting issue. Is the hot start issue new, did the weather change, how old are your plugs, how many miles on the engine, etc. might be better questions.

The O2 sensor is cold when the car is started (even if the car is still pretty warm), and it will read lean until the sensor heats up. I doubt that the pattern you are seeing on the A/F ratio gauge indicates what's really going on with the mixture.

-Max