Wierd Boost results???? Why???Any Help Please?

[95_TSI_AWD_CHIK]

Ok, I think I need a little help here. I have a 95 Talon TSI Awd 5-speed and here are my mods...1gen fuel rail with 650cc injectors, adjustable fuel pressure regulator, 255 walbro, t3 turbo, ported and polished cast manifold, 2.5" custom O2 housing, 3" turbo back exhaust (no cat), 8.5mm wires, turbox bov, ingen intake, manual boost controller, safc II, autometer boost gauge, autometer air/fuel gauge, fmic (28x9x2) w/2.5" piping, 34mm external wastegate. Now here is whats going on, If i start from 1st or 2nd gear and wot, my boost in 1st and 2nd will only go to 16-17psi max., 3rd, 4th and 5th gear she goes to 20-22psi. and holds. its not creaping to 20 either, just goes there and holds throughout rpms. why wont she go there in 1st and 2nd gear??????? here are my S-AFC II settings.... my sensor type is set on Karman, my throttle point is set at 30% for Lo and 80% for hi. my rpm corrections are set the same for lo and hi throttle and are as follows.... 1000rpm is set at -15%, 1600rpm is at -17%, 2200rpm is at -20%, 2800rpm is at -20%, 3400rpm is at -20%, 4000rpm is at -21%, 4600rpm is at -22%, 5200rpm is at -22%, 5800rpm is at -22%, 6400rpm is at -22%, 7000rpm is at -22% and at 7600rpm its at -22% as well. I have not done any logging yet. any suggestions on my boost issues???? please???? and thanks in advance, Liz

 

[olmytsi]

I wouldn't call that an issue. The higher gears have more load thus producing higher boost.

 

[95_TSI_AWD_CHIK]

really, because i expect to set my boost and have it stay where i put it and it did untill i turned it up past 16psi.
does u car do this? thanks for the input.

 

[andymoraitis]

Liz,

This is often the issue with small turbos when they're not under heavy load. I have a 16G on a 2.3 stroker and I never see full boost in 1st or 2nd since the gear duration is very short and there's not a lot of load on the motor due to torque multiplication from the gearing. As you rise numerically in the gears, the ratios drop and you can make more boost in 3rd, 4th and 5th. As an example, I only see about 19psi in second, but in 5th, I can nail 28psi at half throttle.

Olmytsi is right and it's nothing to be concerned about.

Hope that helps,

Andy

 

[95_TSI_AWD_CHIK]

Great, thanks for conferming for me if this is true, i kinda thought that my turbo was the issue, time to search for a bigger turbo. Thanks again. Still will be appreacitive of any other input as well from anyone.