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Discussion Starter · #1 ·
Hello all,

I have a 4T4 turbo installed. I have an Audi MAF connected, bigger injectors, shimmed cylinders and meth injection everything was tuned by Hilton. The car initially ran great, super powerful, made tons of boost quickly, went from 80 mph to 100 in two seconds (more or less) loved it.

I got a Check Engine that indicated Cat operating below threshold error...I don't have a cat, never have and I've used the rear o2 spacer before the turbo and never had any error codes. Then I noticed all the studs from the down pipe had walked lose and my down pipe was just hanging. Torqued them all down, cleared codes.

Now, the car has zero power. The turbo spools and it makes boost but will over shoot, it pulls and feels fine until about 10 psi. Then I feel no power gain. Doesn't look like I have any leaks, car drives perfectly fine otherwise, no other codes.

I thinking it might be something mechanical, maybe my wastegate has changed its settings? I'm thinking the Cat code is incidental and not related?
 

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I can only imagine that downpipe was loose already when Hilton tuned it. Now that its tightened, it changes the spool characteristics.
 

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Discussion Starter · #3 ·
I can only imagine that downpipe was loose already when Hilton tuned it. Now that its tightened, it changes the spool characteristics.
possible, but not probable. I like to think the installer had those bolts tight when he was doing the logging for the tune with Hilton.
 

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I've heard that 4T4 turbo requires some modification to the heatshield on the turbo. It can cause wastegate arm to not fully open the flap or smth. Like it hits the shield and therefore causing spikes. Might want to look into that
 

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Thats impossible to troubleshoot without a datalogger pretty much. It could be anything, but it sounds like a massive boost leak or wastegate open. I'm not as familiar with the S60R at this point, mostly other turbo'd vehicles.
 

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Discussion Starter · #6 ·
Thats impossible to troubleshoot without a datalogger pretty much. It could be anything, but it sounds like a massive boost leak or wastegate open. I'm not as familiar with the S60R at this point, mostly other turbo'd vehicles.
Yeah, that's what I thought might be the case. I'll grab some logs and then post them up.
 

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Related to your cat code. I had ran an o2 spacer on the stock tune with my oem dp. Then once Hilton tuned my car I had him tune out the cat sensing on the rear o2 (possible he did the same to yours). I left the spacer on for a while and I had this same code pop up. Once I removed the spacer and cleared the code in vida I have never had it pop up again.

From my electronic gismo- Galaxy S6
 

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As for the way your car is boosting odly. A boost leak causes these cars to act all kinds of crazy. I thought I had tracked it down to my forge wastegate but upon inspection with a boost leak tester a few leaks presented themselves. When looking at all the piping it all looked solid but apparently it wasn't.

From my electronic gismo- Galaxy S6
 

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Failing TCV? Boost leak? Is the actuator arm still on the wastegate? Need VIDA to look and see everything. Do some dataloging runs.
 

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Since my rebuild and de-catting I've had no ODB codes thanks to my rear O2 sensor adaptor, though a couple times I checked my car with DICE it sometimes had a code for cat efficiency logged. Then when I went to the drag strip last weekend and really beat on the car including a couple runs up past 7K RPM I actually did throw a p0140 code for rear O2 sensor, but reset it and haven't had another since.

That being said, such issues have never changed anything about how my car has run or felt since the rebuild, so if I were you I'd log some data on things like boost, MAF and A/F through some runs to try to get an idea of what's wrong. There might be a chance some ECU adaptations were thrown off when you had that big exhaust leak, so you may also want to reset the ECU and let it re-adapt to make sure all is well in that department as well.
 
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