Interesting. I would think your leak test should have detected an intake leak as the throttle blade is not a perfect seal (and has a hole in it if I recall correctly) but I'm not sure how you tested the charge pipes. Do you have a valve that's hanging open? What's your blow-by like?
Turbo Failure / Upgrade
- Thread starter usmc363
- Start date
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True, it idled and ran fine, and the gauges didn't show an excessive vacuum leak. ugh.
Forgive my ignorance, I'm used to pushrod V8's..All of the intake valves would have to be closed in order to put pressure in the intake and expect it to hold though, I don't know much about the valvetrain timing of the 3.5 to know if that would be possible and would assume it would just go to the exhaust (both valves open with timing) or possibly crankcase and add pressure there, which would probably just blow right out the oil feed/drain tubes that are out since the turbos are out.....right?
Forgive my ignorance, I'm used to pushrod V8's..All of the intake valves would have to be closed in order to put pressure in the intake and expect it to hold though, I don't know much about the valvetrain timing of the 3.5 to know if that would be possible and would assume it would just go to the exhaust (both valves open with timing) or possibly crankcase and add pressure there, which would probably just blow right out the oil feed/drain tubes that are out since the turbos are out.....right?
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Don't worry, I'm a V8 guy too (but it all works the same). If an intake valve is open, the pressure goes to the cylinder. The exhaust valve should be closed so you'll only get some leaking around the rings (blow by). If the intake valve is closed, any leaking would be through the valve stem seal (also blow by). But I cannot imagine enough ring blow by or valve stem blow by to cause no boost. I wouldn't jump to pulling the intake just yet IMHO. Have you looked at your 2 bypass valves? I assume you kept them in for your leak test but did you electrically disconnect them and see if boost builds?
I know that blow by (leak down) is different from compression check, but I would assume that I would see a low compression reading on a cylinder if the rings were shot. I agree with you as well, I don't believe that would be enough to have a no boost situation. Yes on the BOV, inspected the rubber diaphragms, looked good. They were in for the pressure test and held 20psi, then tested with them unplugged and driving, still no boost, then I put two brand new ones on, still no boost.
Got the turbos back in, installed all new EPP piping as well as the oil cooler upgrade. Boost is back with the terrible exception of surging between 1-18psi in WOT. I believe I have an oil contaminated intake MAP sensor. I put a stock one in it and went back to a stock tune and it ran ok. Just ordered a new 2.5 bar MAP from unleashed (I have 2.5 Bar tunes in the LivewireTS). Going back and forth with MAP part numbers and revisions was a biotch let me tell you. Will report back.
Possibly this help?
AA5Z9F479A
AA5Z9F479A
Possibly the inevitable: https://www.fortheworkshop.com/the-definitive-guide-to-replacing-the-hvac-directional-door-actuator/
Passenger side is a cakewalk as opposed to the driver side.
Breaking Down the Source of Significant Oil Burning [Updated]
Introduction Well….I guess it was bound to happen. Just wasn’t looking forward to it so soon. Anyway, I FINALLY got my methanol kit installation completed and was about to take it out on some sea trials. As soon as I got on the road, the car started smoking. Not too bad at first, but bad […]
www.fortheworkshop.com
Welp, the long road is over. Got the new MAP sensor in and I have boost. Reading shows approximately 22 psi assuming this is pre-throttle body MAP (Digital readout from LivewireTS) and approximately 16 psi in manifold (mechanical gauge readout). It's dirty, but here is the most recent pic.
Ha ha me!
So this all came down to a bad MAP sensor?
