940GLE+T runs great, but making ZERO boost

mjk_9574

Hey all, in desperate need of some assistance regarding a +T build on my B230FB 940GLE.

Problem: Car runs, but makes ZERO boost

Parts List for reference:

TD04HL-19T (Angled Flange)
0.5bar Wastegate spring
Reinforced Factory Manifold
3in stainless turboback exhaust
DO88 Intercooler and Piping
“Cold Side” MAF Mod
xxx975 ECU (Chipped for Injectors)
xxx148 Ezk
Deatschwerks 440cc Injectors
Yoshifab Catch Can Kit
Pro sport Wideband AFR Gauge

I’ve spent the last 3 days trying to diagnose the issue, Ive ruled out the wastegate being an issue because it will activate with compressed air applied to it, but not when the car is running even at 4000+ rpm. There doesn’t appear to be any boost leaks, did the spray-bottle-soapy-water test. Tried disconnecting BOV, IAC and just about any other vacuum line in various combinations to see if anything changes and NOPE, NADA.
I tested my gauge with 15psi air from the air compressor and that read accurately. The AFR is stable, fluctuating between 14-15.

What appears to be happening is that the turbo is simply not making enough boost to actuate the wastegate… I pulled the pipe off before the throttle body and could feel it trying to push my hand off when I held it over the end of the pipe. I even bypassed the intercooler which only decreased the vacuum display from -20psi to -5psi…

Anyone have any suggestions?
Cheers

Philia_Bear

Where is the amm in the set-up?

mjk_9574

Philia_Bear The AMM (or MAF) is located after the intercooler. I was told this was a viable mod and it was convenient for me to not have to rewire the harness to the drivers side as the NA car has it in the passenger side.

I got the tuning chip to suit this, im addition to having the new input for my 440cc injectors, it removed the “boost-cut” setting in order to run the MAF on the cold side

Dauntless

I'm thinking it has to be the wastegate or a leak somewhere, as that engine and turbo combination would have to make boost under full load at high revs.

Can you confirm the wastegate flap seals properly to the housing? Does the actuator hold it firmly in place? If the actuator is super weak it could blow open with exhaust flow, but you'd normally still see some boost before this happens.

Does the turbo sound like it's spooling up? Does it spin freely by hand, and generally sound normal?

Have you pressure tested the piping/intercooler/intake etc with the engine off?

AlaskaJono

I had a similar issue when I had some exhaust work done on my old Saab 9000. After I picked up the car from the shop, the Turbo basically did not kick in, and I was travelling at the speed of a moped. Brought it back to the shop, and the young dude crawled underneath and loosened the pipe to turbo and it didn't move freely. Hmmm. So after he put it all back together, I got out my hammer out the boot, "the Persuader" = a large Ball Pean hammer (maybe 1Kg) then the "Love Tap". Literally just a light but evident TAP/TAP. This jarred loose some micro debris and the car was free to turbo again.

Otherwise, I agree with above, the sticky wastegate syndrome is a possibility. Some dremel out the inside so that the flap can never stick again this lifetime. See how you go.

Dauntless

AlaskaJono I'm struggling to visualise how this would work? The wastegate can be ported to minimise boost spike, but that isn't the issue here.

OP said the WG actuator moves when compressed air is applied, so we know it isn't stuck. If it were stuck shut we'd see overboost. We don't know if the flap is still attached to the arm, or anywhere close to sealing the orifice in the turbine housing.

AlaskaJono

We don't know if the flap is still attached to the arm, or anywhere....
Yes for this idea. Probably get a set of fresh eyes and hands on it. Hopefully it is a small thing/easily addressed.

Dauntless

dmc

does the wastegate close properly? sounds a lot like it falls open or is jammed open.
i had the same when the wastegate actuator rod fell off the lever. (it was a test drive to test boost level hence no R pin). seems you have tested for this though.