T25 + FMIC = Lag at WOT

[mramc3]

I have a 95 tsi awd that I just returned to stock form for smog certification. Ran smoothly. Then I put in UIP, LIP, and Injen Intake, and Greddy FMIC. I started the car and let her idle for about 15 mins. Then I took her for a spin. When I stepped on the gas it hesistated then built up full boost. 2nd gear same thing, bog a little then hit boost, then the IC disconnected. I am assuming the the large Greddy FMIC is overkill for the turbo, but can someone explain why it causes the lag?

I switched out the FMIC to the stock sidemount. Runs a little better, but I still have the occassional bog and hesistation. Any ideas on whats going on?

Jeff

 

[sumenlo]

sounds to me that with the addition with you IC piping, you've somehow created a boost leak. Double check all your junctions and clamps to make sure they are all sealing correctly.

 

[psychlow]

Another vote for boost leak.

FMICs should not create lag - turbos move so much air that a little increase in intercooler volume doesn't take more than a fraction of a second to fill up.

 

[97spyder maayng]

I HAVE THE SAME PROBLEM!!! ...i couldnt resist the cheap kinetic fmic that i got a nice hookup for, i guess serves me right.

Also, i have a SAFCII. When i had the car run without it, it bogged, but when i connected the safcII it reved smoothly. Also it seems im running mid stoichimotric to mid rich in the a/f mixture.

Anyone know whats going on?

 

[Bigglesworth87]

Generally when i return my car to stock it takes some time for the ecu to reconfigure itself and sometimes you gotta reset the ecu so that way it has a clean slate. You are right about that front mount being over kill for the t25. Its not the biggest turbo out there and the little sidemount is enough for that little guy. Also, front mounts generally create lag on turbos.

 

[olmytsi]

I also vote for the boost leak. Also, did u put ur exhaust back on yet?

 

[oldman]

FMIC + piping without a boost leak test is just asking for it if you ask me.

 

[mramc3]

well the exhaust is back on of course, I don't really know why that was asked. But I heard that larger intercoolers cause lag with the T25. Regardless if it is 1 sec delay, its still lag and its still there.

Boost leak test will be my next step. As far as the ECU is concerned I d/c the battery when I did the install, and I let the car run idle for 15 mins before I drove.

I honestly know I have a boost leak somewhere, but I won't be able to get to it till this weekend.

 

[oldman]

I honestly know I have a boost leak somewhere, but I won't be able to get to it till this weekend.

That's fine but until then, show some maturity and consideration for you car by easing off the throttle. Good luck.

 

[mramc3]

That's fine but until then, show some maturity and consideration for you car by easing off the throttle. Good luck.

Will do. I've been babying it trying to keep the boost under 8 psi. After all the fixing that went into it, I'm not trying to mess things up this time.

 

[oldman]

I've been babying it trying to keep the boost under 8 psi.

I was thinking more like NO psi.

 

[xcelr8n]

On my 14b its damn hard not to boost even during normal driving, especially with an exhaust, I imagine the t-25 is even worse.

 

[oldman]

On my 14b its damn hard not to boost even during normal driving, especially with an exhaust, I imagine the t-25 is even worse.

Easy fix, just disconnect the actuator arm and drive it like a N/A.

 

[punishercb]

Easy fix, just disconnect the actuator arm and drive it like a N/A.

Wow, I bet that'd be slow. Would the car still run just fine?

 

[oldman]

Wow, I bet that'd be slow. Would the car still run just fine?

Yes, it will drive fine. Depending on how well the turbine and wastgate path are ported, you can still build some boost at higher RPMs. I was able to build about 7psi by 6k (WOT) and only 1-2psi after a complete port job.

 

[flinguist]

Wow, I bet that'd be slow. Would the car still run just fine?

I'm running with my waste gate actuator disconnected right now until my new clutch is broken in. Yeah, the car is real slow, but it runs fine. I think the NA 2.0 litre is around 130 to 140 HP, which is pretty doggy compared to 280 to 300 HP I have with the turbo.

 

[MrPikolo]

I'm running with my waste gate actuator disconnected right now until my new clutch is broken in. Yeah, the car is real slow, but it runs fine. I think the NA 2.0 litre is around 130 to 140 HP, which is pretty doggy compared to 280 to 300 HP I have with the turbo.

Thats with a higher compression than what you have as well. So it will be even less.