overboosting after 6k rpm?
Back on topic...I have experienced this same exact issue. My mods are in my sig and I've triple checked my lines off of the mbc. 1st and 2nd gear I can nail 20psi and it's rock solid all the way to 7k. If I do a 3rd gear pull it peaks right at 20psi, up until just before 6k and then jumps to 22-23. If I try to pull to redline in 3rd, it cuts the fuel. I originally thought it was simply do to the fact that it's only getting into the 20's (air temp) around here during the day, and in the teens at night. I also thought it could be because I haven't installed my fuel pump and got the car tuned yet. I still don't understand why the boost actually creeps higher instead of tappering closer to redline
Last edited by MasterNater; Jan 21, 2007 at 06:44 PM.
I'm not worried about the diagram you followed. I'm telling you to go VERIFY that you didn't switch the nipples on the MBC itself. It's very easy to do and has been done many times. I've done tons of MBC installs and have still made that same mistake once.
MasterNater, that's very disconcerting. Boost should not randomly be climbing at 6k. This is the first I've heard of it, so I don't know what's going on. Also, I know people hate hearing it, but it's highly unlikely that you maintain a FLAT boost level at 20psi in both 1st and 2nd gear. The stock turbo always tapers with an MBC, and there isn't enough load in 1st and 2nd gear to keep it from tapering. By 7k, it's guaranteed that your boost is a few psi below 20. Verification requires a MAP sensor - can't base it off the gauge.
MasterNater, that's very disconcerting. Boost should not randomly be climbing at 6k. This is the first I've heard of it, so I don't know what's going on. Also, I know people hate hearing it, but it's highly unlikely that you maintain a FLAT boost level at 20psi in both 1st and 2nd gear. The stock turbo always tapers with an MBC, and there isn't enough load in 1st and 2nd gear to keep it from tapering. By 7k, it's guaranteed that your boost is a few psi below 20. Verification requires a MAP sensor - can't base it off the gauge.
Okay, I apologize...I should have made it more clear that it hits 20 in 1st and 2nd but doesn't go beyond. I'm sure it does tapper but it's hard to look from the boost gauge to the tach and keep an eye on the road in 1st and 2nd. I am still concerned with it going beyond 20 around 6k in 3rd and I'm even more concerned now that you haven't ever heard of it.
Any suggestions? Maybe put the stock boost solenoid back in, see if that keeps it from going beyond 20? Another note, I have the Forge MBC dialed all the way down and I still hit 20. Is this normal? I would have thought it would be more around stock wastegate pressure or maybe a little higher, like 15?
Any suggestions? Maybe put the stock boost solenoid back in, see if that keeps it from going beyond 20? Another note, I have the Forge MBC dialed all the way down and I still hit 20. Is this normal? I would have thought it would be more around stock wastegate pressure or maybe a little higher, like 15?
Alright, you sound just like me. Same problem, it goes up a bit instead of tapering down. Also I get fuel cut (sometimes). I had my MBC installed by a local performance shop (well known among some evo around here) and they guy tells me that a boost spike is a normal thing for MBC. Definately not what everyone thinks here, so I don't know what to do now either....
Is your car tuned?
Alright, you sound just like me. Same problem, it goes up a bit instead of tapering down. Also I get fuel cut (sometimes). I had my MBC installed by a local performance shop (well known among some evo around here) and they guy tells me that a boost spike is a normal thing for MBC. Definately not what everyone thinks here, so I don't know what to do now either....