Mapachurro
Well-known member
Hey everybody. I've been working through this issue for about 10 days, and there's no one clear issue, at least not that I understand. Here's a breakdown:
Problem: Stock K03 VNT-15 on a BEW, engine with roughly 250,000 miles; suspect similar mileage for the turbo. Boost levels normally 12-15, with spikes to 17; in the last few months, lower boost than normal, down in the 10-14 range, no high spikes. In the last two weeks, limp mode: kicks in when gunning up the engine, error code P0299.
-Since acquiring the vehicle one year ago, five days a week, at least once a day, I gun the engine WOT in 4th gear on a highway onramp, hitting 3800-4200rpm for 5-10 seconds.
-Limp mode kicked in, 11/26.
-On 11/27, MAF sensor removed, replaced with a gently used (less than 10,000 miles) Bosch MAF sensor, heavily cleaned with electronic cleaner before install.
-On 11/27, actuator rod heavily soaked in PB Blaster. This appeared to solve the issue; limp mode reoccurred 12/3. Soaked again on 12/3, again on 12/5.
-Vacuum lines are all in good condition, checked as per diagram on 12/5. The brake boost was the only one I was unable to access physically/visually.
-On 12/5, lubricant applied under the cap of the N75; no further testing or swapping of the N75 has been performed.
-Turbo actuator tested with mightyvac, 12/5. Movement began at about 3psi and ended around 18-19 psi, but did not appear to reach the full stop location. There was no crunching, and the actuator rod's movement was fairly fluid.
-The purple wire coming out of the smart actuator has some damage to its insulation. It doesn't appear to have reached the wire inside, and has no kinks or full-on breakage.
-The actuator has been replaced previously; the two bolts holding the bracket on are not OEM.
-There appears to be oil seepage from either where the vacuum pump meets the head, or from the turbo manifold's gasket to the block, or both
-The hot side turbo/exhaust downpipe gasket is so rusted that it has spread out in a fan of rusted layers. There may be an exhaust gas leak there.
-In general, other IC piping seals are normal oiliness for a TDI; SMIC has been drained on a regular basis of oil, always with only a few ounces present
-The s-shaped intercooler pipe at the compressor outlet, while firmly clipped in, has a few millimeters of play in the compressor housing. There may be a boost leak there.
Limp mode goes away with lubricant being applied to the actuator rod, but this doesn't last. Limp mode will kick back in sometimes when driving at lower speeds, and always at highway speeds; sometimes with CEL, sometimes not. Boost never goes above 12.
So. I've been planning on buying a VNT-17. I almost have the money for it. I don't have the money for a tune, yet, but I can at least slap the VNT-17 on and drive it like a VNT-15 (right??) until I get the money/time for a tune and to put my VR6 clutch in. But it would be nice not to *have* to do that ****, right now, right before Christmas.
I think my next move is replacing the exhaust downpipe gasket and pumping engine cleaner into the turbo hot side. I'm also going to look in my spare parts for an N75. Any suggestions are greatly appreciated!
Problem: Stock K03 VNT-15 on a BEW, engine with roughly 250,000 miles; suspect similar mileage for the turbo. Boost levels normally 12-15, with spikes to 17; in the last few months, lower boost than normal, down in the 10-14 range, no high spikes. In the last two weeks, limp mode: kicks in when gunning up the engine, error code P0299.
-Since acquiring the vehicle one year ago, five days a week, at least once a day, I gun the engine WOT in 4th gear on a highway onramp, hitting 3800-4200rpm for 5-10 seconds.
-Limp mode kicked in, 11/26.
-On 11/27, MAF sensor removed, replaced with a gently used (less than 10,000 miles) Bosch MAF sensor, heavily cleaned with electronic cleaner before install.
-On 11/27, actuator rod heavily soaked in PB Blaster. This appeared to solve the issue; limp mode reoccurred 12/3. Soaked again on 12/3, again on 12/5.
-Vacuum lines are all in good condition, checked as per diagram on 12/5. The brake boost was the only one I was unable to access physically/visually.
-On 12/5, lubricant applied under the cap of the N75; no further testing or swapping of the N75 has been performed.
-Turbo actuator tested with mightyvac, 12/5. Movement began at about 3psi and ended around 18-19 psi, but did not appear to reach the full stop location. There was no crunching, and the actuator rod's movement was fairly fluid.
-The purple wire coming out of the smart actuator has some damage to its insulation. It doesn't appear to have reached the wire inside, and has no kinks or full-on breakage.
-The actuator has been replaced previously; the two bolts holding the bracket on are not OEM.
-There appears to be oil seepage from either where the vacuum pump meets the head, or from the turbo manifold's gasket to the block, or both
-The hot side turbo/exhaust downpipe gasket is so rusted that it has spread out in a fan of rusted layers. There may be an exhaust gas leak there.
-In general, other IC piping seals are normal oiliness for a TDI; SMIC has been drained on a regular basis of oil, always with only a few ounces present
-The s-shaped intercooler pipe at the compressor outlet, while firmly clipped in, has a few millimeters of play in the compressor housing. There may be a boost leak there.
Limp mode goes away with lubricant being applied to the actuator rod, but this doesn't last. Limp mode will kick back in sometimes when driving at lower speeds, and always at highway speeds; sometimes with CEL, sometimes not. Boost never goes above 12.
So. I've been planning on buying a VNT-17. I almost have the money for it. I don't have the money for a tune, yet, but I can at least slap the VNT-17 on and drive it like a VNT-15 (right??) until I get the money/time for a tune and to put my VR6 clutch in. But it would be nice not to *have* to do that ****, right now, right before Christmas.
I think my next move is replacing the exhaust downpipe gasket and pumping engine cleaner into the turbo hot side. I'm also going to look in my spare parts for an N75. Any suggestions are greatly appreciated!