Some history: my car had a stage 4 setup and now has been upgraded to a gt640 kit.

The Problem: under hard acceleration the boost comes on strong then drops and then rises again. I am seeing spikes of 1.5bar

I saw this happen on the stage 4 setup too.

What could this be?

I have been told it could be that the car is overboosting and the TB is shutting down and then opening. But what could be causing my car to overboost?

TIA

Jags

 

I am not a pro, but could it be some kind of "boost creep" from the wastegates. I have heard about this from a guy at work with a Sub WRX STI. He said when he gets on, the car kinda shutters at full boost. Trust me I have no idea though.

 

when its cold u will see spikes but thats all it is... i see 1.5s as well... then it drops off to 1.3 bars...

 

I can understand spikes but what about the fact that boost maxs quickly and then drops and then maxs again at the top of the gear

 

I see... its the after market actuators(wastegates) that are causing this.. maybe something is not set up correct.... the nuts on the spring maybe be not in the appropriate spot.... but then if u say it goes up and down... something with the wastegates in my opinion... I ve had 3 tuning packages myself and I have doen plenty of "screwing" around" with the set ups... is it happening in cold weather only.... or both....
so if it spikes 1.5 .. what does it drop off too? and then it spikes and holds again at what bar?

how long is the spike for.... and in what gears?

 

You think its the wastgates but this happened with the stage 4 kit and the gt640 kit. I only see spikes on 1.5. It will drop down to .7 and the climb again. I have seen this in 60 degree weather. It has not got warmer than that yet. I have seen it in 1-4 gears. Never pused it in 5-6 yet with the current setup

 

did u have the same turbos on both set ups???? if so then its ur wastegates...
if u got new turbos on the gt640 .. then Im thinking its something else...
where did u get the kit.... Stephen or evoms... call them asap... they should help... but that very irregular...
Im thinking that ur overboosting... ur set up is not up to par, soething is not calibated... like ur waastegates... and ur car pulls back timing and or goes into limp mode.... especially if ur hitting 1.5 bars.. these ecus are designed to go into limp mode after 1.3 bars...
call ur tuner... for $20k u should not have to go thru this....

 

I am suspect of something else such as a MAF or sensor due to the turbos are not the same and the situation is happening in either setup. The wastegates are not the same either, nor the program. It was all changed.



The program is to allow 1.3+ spike for a second that’s it. The TB will not close with this program until much higher. The other issue could be the reducers the install shop used to step the line to the wastegates. I have no seen it but this could cause it as well. A faulty or lazy boost valve. The list goes on. The one constant here is the car, not the kits

 

The stage 4 setup had kevins stage 2 turbos. The gt640 kit has garret turbos. The kits were bought from AI. The reason I dont think its the reducers is because I saw this happen with the stage 4 setup to and reducers were not used then.

 

Check your boost in 5th or 6th, on flat or uphill grade, then it should stabilize. Also dont take your "boost" figure as gospel, as the in dash only indicates a calculated figure, instead install a 930 style tattle tale boost guage ( mechanical ). Jay.