Turbo spool problem.

[Ultimatedsm]

Hey guys how are you? Ever since I did this 1g 6bolt with a 14B install in my 2g I have been having really bad turbo lag problems. I checked both compressor cold/hot side and they were fine. When I am in 2nd gear and punch it, I hit full booost around 3000 rpm. However, lets say I punch it in 2nd redlining it, then shifting into 3rd then punch it again, the boost takes forever to build, it just slowly climbs. However, if I am in 3rd rolling at 3000 rpm, I get full boost pretty quickly, but then if I am boosting in 3rd than shift into 4th then punch it again, the boost takes forever again! Damn it, it is really annoying and severally killing my cars performance. I have done boost leak tests and the 1g BOV is leaking slightly but not a lot. It doesn't leak enough to make a significant boost lag problem. Alright guys help me out here, help me fix this annoying problem. I lost to an STi today and was pissed because this lag really dragged me back. My mods/setup:

1995 Eagle Talon TSi
1G 6 bolt engine (155 across the board)
14B turbo
walbro 255LPH /w AFPR
450cc injectors
DSMLINK
3 inch exhaust (turboback + high flow 3 inch cat).
MBC (TURBOSMART) set to : 15PSI (Goes to 16-17psi sometimes).

 

[oldman]

What's up cool Canadian?

The only thing I can think of which will effect your car the way you described is the mbc, particularly its ability to relief wastegate pressure between mbc and actuator. Every mbc should have a little bleeder hole on the outlet nipple to the actuator so that pressure will not get trapped after you let off so that the wastegate will close properly. I'm not familiar with a Turbo Smart unit but I suspect either the hole is missing, too small or the volume between your mbc and actuator is too large. How is your mbc setup? BOV VTA?

Test run without the mbc by connecting a hose between the J-pipe and the actuator and see if problem persists. Good luck.

 

[GVR4592]

I just picked up a $300 fwd beater car for the winter and the turbo gets 15 psi about 3400 rpms. I thought boost leak for sure, so I did a boost leak test and there were no leaks. I took a closer look at the turbo and found out that was not a 14b, it was a 14g. That's not a typo. I don't know what vehicle it comes from but it has an 8cm turbine housing and that is why the damn thing took so long to spool. That is most likely not the cause of your slow spool but I thought I'd throw that out there just in case.

 

[Ultimatedsm]

What's up cool Canadian?

The only thing I can think of which will effect your car the way you described is the mbc, particularly its ability to relief wastegate pressure between mbc and actuator. Every mbc should have a little bleeder hole on the outlet nipple to the actuator so that pressure will not get trapped after you let off so that the wastegate will close properly. I'm not familiar with a Turbo Smart unit but I suspect either the hole is missing, too small or the volume between your mbc and actuator is too large. How is your mbc setup? BOV VTA?

Test run without the mbc by connecting a hose between the J-pipe and the actuator and see if problem persists. Good luck.

Whats up Boost leak telling master? Its about time you answer, just kidding The boost controller is hooked "T" off with the BOV line while the other size is connected to the wastegate actuator. I am suspecting a MBC or shimming off the actuator on the turbo. It could be possible that the wastegate actuator doesn't close properly sometimes. I like how you gave me possibilities that make sense. Thanks a lot Oldman!

 

[oldman]

Whats up Boost leak telling master? Its about time you answer, just kidding The boost controller is hooked "T" off with the BOV line while the other size is connected to the wastegate actuator. I am suspecting a MBC or shimming off the actuator on the turbo. It could be possible that the wastegate actuator doesn't close properly sometimes. I like how you gave me possibilities that make sense. Thanks a lot Oldman!

You're welcome, did you test run with the mbc bypassed? That would tell you if the mbc is the problem.

 

[Ultimatedsm]

I know this is an old thread I haven't updated you guys on this. I found out my MBC was bad, it would cause a lot of lag inbetween shifts. I also did a boost leak test and found out one nice major leak, however, it wasn't enough to make the car fall flat at WOT. The compressor I used wasn't very strong, about a 2.5 Gal with a max 90 PSi of pressure. Anyway, I have a FMIC with 2.5 inch piping for a side to side intercooler. Because of the type of intercooler, my piping was a little longer than a short route FMIC kit.

So I turned on the compressor, my girlfriend checked my boost gauge 1....2....3..4...5...6....6....psi couldn't go past that (Compressor maybe not strong enough to over come the leak). But when I boost, I can easily hit 18 psi but I can feel that its leaking due to a performance loss.

So this leak I can hear it hissing really loud, I couldn't hear it from the piping and then evenually I start sticking my fingers where the fuel injectors are. I found out one of my fuel injector seal isn't good, I can actually feel the air pressure when I fill the intercooler piping with compressed air (Feels like having a very very little hole in the tire where the pressure leaks out enough where you can hear and feel it). Well thats not a good sign, I had a feeling the car wasn't performing like it should, my gauge would read 10 psi when I go WOT but the car wouldn't go anywhere for a second then boom it hits I guess thats because of that leak and the turbo working harder to over come it.