I put on a 2.5" RB DP to a resinator and exhaust shop made for me to a RB 2.5" cat-back and now im only boosting 4psi!!!! I do not have a FCD or ported waste gate, my air pump is still hooked up but its not hooked to the exhaust, I was thinking maybe boost creep or fuel cut what you guys think???

:-(

 

well its deff not boost creep. that is when you will notice as you get to the higher rpms the boost will raise beyond what it is set at meaning if you are set at 6 psi and seing that through most of the rpm band then the last few hundred it jumps to 10 that would be the issue. And if it were fuel cut you would typically notice boost hitting around 9 psi or so with an s4 and it would hit that then immediatly the car would bog or shake because the ecu is stopping you and the boost would stay lower than 9 but probably not 4. So if it just acts like it always did on the stock boost setting then there is something in your exhaust holding everything back. Is this resonator the same size as your dp or is it smaller??? It really sounds like there is something bottlenecking not. I can say it def not boost creap though.

 

the resinator is 2.5" opening then its about 4" around inside im not sure what it is but it looks nothing like a cat or glass pack, you cant see through it, the exhaust shop said it would flow alot more then a cat though. Could it be the resinator??? could it have something to do with the air pump not going to the exaust I dont think he put the checkvalve backon could air be going back to the engine causing backpressur??? I have no boost controller or FCD not sure if that matters either also I havnt adjusted my bov could that have something to do with it as well??? how much boost should I be seeing???

 

Well how much did you make stock?? you should see maybe 1-2 psi and maybe 2 solid if you have an intake on an s4. i added full 3 inch exhaust and a cone filter and saw 3 psi but every car is differen. For a while I had all the emissions stuff still there just the pump pumped extra air into the atmosphere under my car(all lines were there except the one connected to the cat. Take a look under there and see if air is being pumped into the cat. It made no difference on my car to just let it hang there. Also a bov has nothing to do with it either and the stock one is not adjustable. The only things that affect something like this would be a restriction or vacuum leak is my guess. From what you describe it could be a resonator or cat. Most cats you cant see through but resonators you should be able too(Mine you could). maybe its a bad resonator. Was it brand new or used???

 

Just throwing this in, but is the wastegate ported?

 

it was new. the exhaust isnt loud at all its pretty much just as quiet as befor and i was running the same stock 4-5 psi. and no the waste gate is not ported.

 

Just went and drove it again turns out in first im only getting 2-3 psi then 2nd and 3rd in getting 4 close to 5 psi

 

It's not boost creep, nor is it fuel cut. I say the resonator is causing a restriction. It's the only thing it can be if you have a RB DP & RB cat back. If the resonator isn't welded in, have them put a "test" pipe in there and give it a try. You should be seeing 5/7 lbs I would imagine. The 2.5" system isn't going to peg the boost ga, but it should give you slightly more than stock.
What is the type of resonator they used? A good/high flow cat doesn't restrict the exhaust very much.
Make certain they or someone didn't disturb the air intake system when working on the car. Make certain all clamps and hoses are tight from the AFM to the UIM.

 

yeah ive got to think the same that this resonator is creating a bottle neck in your system. Get a 2.5 inlet and outlet high flow cat or test pipe and that should go away. Did they weld or bolt the resonator in the system????

 

no it has flanges, how loud will it be with just a test pipe??? also it seems in first its kinda strugeling then second and third its not as bad.

 

Do you have a proper aftermarket boost gauge? It seems unlikely that the resonator is *that* restrictive, but I suppose it's possible. Ask the shop what kind of resonator they used, but it sounds like it would be a straight through design. Are you certain that the vacume hoses to the boost gauge are all properly connected?

The airpump, etc. should have no effect on the boost.

 

Stock boost would be 6psi, since you're not even getting to there, there's something either wrong with the turbo, wastegate, or you have a boost leak. Your wastegate is stuck open, ported WAY beyond the stock flapper, or simply fell off of the arm to control it. Or, you have a leak that when boosting is leaking the air out of a hose/etc, check all IC connectors/etc. Also, I seriously doubt it's anything to do with your exhaust.

 

I have a autometer boost gauge, Im gonna check all my connections and also gonna check to see if the turbo spins freely and has no play.
thanks to every one for the help so far.

 

Also check the wastegate arm (comes out of the actuator) and make sure it's attatched, if it pops off you'll have trouble boosting (similar to what you describe)

 

hmm maybe whoever put the exhaust on damaged or moved something and cuased a boost leak like sonicrat said

 

hmm maybe whoever put the exhaust on damaged or moved something and cuased a boost leak like sonicrat said

 

Ok here is what I have found so far the turbo inlet pipe is cracked where it connects to the turbo, and there is a vac line that is pretty tight and kinda kinked. Also there is some kind of oil on the turbo outlet befor the bov and intercooler. here are some pics.

 

Im lost on the wastegate arm I cant get that off with out taking off the turbo can I?

 

did you carefully inspect all boost pipes?

 

Im kinda still kinda new to the turbo stuff boost pipes meaning intercooler and all pipes connected to the turbo?

 

The wastegate arm is attached should i be able to move it or not???

 

No, it shouldn't move by hand. You're going to have one serious issue with idle/everything else with that cracked inlet pipe. Replace it by either making a new metal intake, or buying a new (not cracked) one. It's basically a large vac leak there. Check all of your intercooler connections (basically every hose coming off of the turbo's outlet, just follow them all around and make sure they're tight and clamped down properly). It's kind of hard to see the wastegate arm, but it comes out of the round actuator that's bolted to the front of the turbo and goes back near the rear of it and is attatched to a lever/arm/linkage/whatever. That's the connection that you want to make sure is attatched properly.

 

yes its connected.

 

Ok I taped up the turbo inlet pipe temp. with some high temp sillicon tape till i can get a new one. and I left the air pump off. it did alot better boosted 4-5 in first and 5 in second. but when it gets to 6,000 RPMs it bogs down and looses boost. also I can hear an air leak from behind the intercooler or down by the downpipe. Its to dark and the car is hot im gonna look at it more tom. any input?
thanks

 

Ok I taped up the turbo inlet pipe with some high temp sillicon tape till i can get a new one. and I left the air pump off. it did alot better boosted 4-5 in first and 5 in second. but when it gets to 6,000 RPMs it bogs down and looses boost. also I can hear an air leak from behind the intercooler or down by the downpipe. Its to dark and the car is hot im gonna look at it more tom. any input?
thanks

Where can I get a new inlet pipe?