S4 T2, all stock aside from unknown exhaust (was on the car when I bought it, prev owner didnt know what it was either). Emissions removed, autometer boost gauge is hook up to the bottom nipple on the back of the UIM.

Gauge reads nearly 20 psi in 4th gear at about 6k rpms. I have a stock ecu so...wouldn't I be hitting fuel cut at like 6 psi if the gauge is reading properly?

Not exactly sure what fuel cut feels like.

 

if theres a fuel cut defender no.

 

fuel cut feels like your hitting a brick wall.

 

Well, there is nothing like that going on...

This I know....but as far as I know the fuel cut should be still working.

 

The stock turbo can't make 20psi at 6k RPM in 4th. At 3-4k RPM, sure. With my wastegate completely closed, the most I can see around 6k RPM is 9-10psi. Cold air temps, which I'm sure you have in Minnesota, will allow slightly more boost under all conditions, but not ~10psi extra. Something isn't adding up. And yes, fuel cut is at 8.6psi, so if you actually pass that level you have an FCD or chipped ECU.

 

This is why im confused. like I said...the whole car is stock aside from emissions delete and exhaust, ecu is stock aswell. Before I did emissions delete...I had the guage T'ed into the boost pressure sensore vacuum line and it would give me even weirder readings, like 5 psi at redline in first. Then something like 10 psi at redline in second.

I mean, the car doesnt move like its making 20 psi of boost, so yeah

 

that sounds a little better, your not usually gonna get full boost in first iirc, there isnt a lot of load on the motor and its a really short gear, im an n/a guy so i may be wrong, but what this is what i remember from working on turboed cars. You're not gonna be getting full boost at redline either iirc, it starts to drop off.

 

Thats sounds bout right. Sound like your using the wrong vac source for a boost gauge. 10psi sound like you do either have a FCD or Chipped ECU.

Boost by gear, 1st gear you can't hit full boost, 2nd and 3rd is where the power comes in. Yes it does taper off near redline.

 

hm, it doesnt really do that....it just keeps building all the way to redline.

 

Bench test the pressure gauge with a bike pump? Peak boost will always be around 3-4k with the stock turbo, and it'll drop towards redline.

 

just to be clear. the stock turbos can hit 20psi of boost. i have done this (accidently) a few times before. and a friend of mine did this on purpose.

easy way to check your vacuum/boost line source. just look at your vacuum reading on your gauge. should be in between 15-18. then try another source well known source, if it reads the same, its a correct reading. try the one on the upper manifold where the upper and lower meet. also, try the ones on the side of the upper just behind the throttle body. theres good vacuum sources all over the manifold.

by your boost sensor (map sensor) is where the fuel cut off would be if you have one. it will look like a small black box usually. most are plug and play, so it will be in between where your boost sensor plugs into the harness.

its not feeling like 20 psi cause you can reach that amount of boost and not gain any significant power.

 

The gauge probably does not read in psi. Does the gauge happen to have writing on it that looks something like "In Hg"?

 

vacuum half is Hg, boost side is psi.

 

Yes, it can around 3-4000 RPM, but not at 6000 RPM in 4th gear. Under that kind of load, the small turbo is starting to become an exhaust restriction.

 

But the stock turbo is only good at 12psi. Why go so much after that?

 

the wastegate could be ported, the turbo could be clipped. What side is the downpipe and exhaust?

I would try to get that boost down. As far as I know the stock turbos become significantly inefficient after 12PSI.

I had a stock S4 turbo that would spike up to 17psi with an FCD and a 3"DP and 3" exhaust.

 

thats what I want to do....but im just thinking the boost gauge is wrong or at least thats what I hope. I dont see anything that could be a fcd.

 

Have you taken a look at your ecu? It might be am rtek or something, in which case the fuel cut would be disabled as well, also it could be an NA ecu which wouldn't have a fuel cut. Chech out the ecu and report back what you find.

 

its a N332 ecu that I bought from someone on here.....I was told it was stock. I suppose could slap on the old ecu but that has Jet Performance chip in it.

 

If there is no FCD and it is the stock ecu then I can't see any reason why there wouldn't be a fuel cut. But fuel cut aside, I wonder if your wastegate is somehow staying shut.

 

now that I think about it..I did drop the gauge pretty hard when I was putting it in, possibly that messed it up?

Either way, I'll be taking the turbo and manifold off seen so, I'll check out the waste gate then...

 

I removed a stock turbo that the wastage was stuck shut. i had to remove the arm and beat it with a hammer for it to open, and still wouldnt full open. I had to soak it for 2 days with PB Blaster, and every hour or so wiggle the arm up and down and add more PB Blaster. So check if the waste gate door is able to move...

 

should I be able to move it by hand with it on the car? If so...I tried and I cannot.

 

No you cannot, until you disconnect the waste gate c-clip. Then you can pop it off the wastegate flap and move the wastegate rod.