Most def

 

These APS single T boost drops are very aggrevating to many shops and customers. We too, have had 3 APS single T cars demonstrate this boost drop issues. We spent about 10 hours trouble shooting a customer's APS single T, and tried everything that has been mentioned in this thread, and more. The only thing we succeeding in doing, is getting more peak boost, but the drop-off pattern was identical.

Not really sure what else can be done. We've tried springs, shimming, shortening, two different styles of boost controller, no exhaust...you name it..we tried it. Best of luck, but its going to be a challenge.

FYI: Unless you are plotting boost on a dyno, it is sometimes difficult to tell that you are actually loosing boost pressure.

 

i agree, peak boost is increased but it still drops off to the same number, its like the car is fighting the boost.

most people say they dont lose boost but it is hard to tell unless you log it, mine seemed fine for a while, then i dynod and logged it and noticed it was still dropping bad.

 

forge sends 4 springs, a 5-9 green, 9-15 yellow, 12-19 red, 17-25 blue. not sure about the last 2 but the the one im using is the 9-15psi range. i might try what you did and cut the threads down a little. i tightened it as far as it would go but it ran out of thread.

 

What is really strange is that when the kit was on my car (I sold it to sugarspun), i did not have this issue at all. I was at 8 psi at redline. Same exhaust.

 

hmm, since the kit has been installed, taken off, reinstalled, im leaning towards a busted flex joint on top of the tranny.

 

You would probably hear an exhaust leak, and definately see the soot. Worth a look.

 

i never did hear the leak, i finally looked at it and saw all the soot. i guess with it being right there are the motor/tranny, its hard to hear.

 

that sounds bad.
also another thing i didnt mention. the kit is used. the kit was working just fine on the guys car that i purchased it from. he was peaking at 10 psi and tappered down to 7.5 at redline. he made 398whp and 401tq. I have all of his parts except the plenum. that i purchased new from you.

 

what does an exhaust leak sound like?

 

Just a loud fluttering noise...but will also see black soot around the area that is leaking.

Oh, so now you are blaming me for the boost drop...due to the APS plenum I sold you? haha...just kidding.

 

Are people still having this problem even with a HKS EVC 5 Boost controller?

 

hahhhaaa nah. i was just stateing that the plenum is new.

 

just look behind the motor from the top, behind the throttle body, and look down onto the transmission, if its leaking the transmission will look black.

 

Sorry to hear that... I have the same problem too so I am putting on a Greddy TT. Expensive solution, I know...

 

Ive heard a lot of problems with the APS ST loosing boost. Kinda scary.

 

i am thinking more and more that i am f--ked.

 

I'd have to say there has to be a leak or vaccum line that's leaking to cause it to open the WG even with an EBC?

Shouldn't the stock kit taper off like most kits do?

 

What type of BC do u have?

 

I'm going to think out loud. If the WG is controlled by vaccum and it is opening early, doesn't that mean that it's reading higher than it really is. If so wouldn't a clogged line or maybe kinked or melted line that may be okay until the vacuum picks up a bit cause higher readings and open the WG.

Like sticking a sock in a vacuum... it creates more suction?