Hey guys, first time poster long time lurker here, got a bit of an annoying issue here I've been trying to diagnose for over a year now, I've tried searching many forums, all the info I've found has either been inconclusive or hasn't solved my problem. I'm hoping one of you guys may have some insight, and either way I'll update this thread with the answer once I find it because it seems like a lot of others are having the same or similar issues.
My car is a 2005 Jetta Wagon with BEW, 380k Kilometres on the odo, basically after 3 years of ownership it started doing this thing where on a cold start the gas pedal won't work at all, to elaborate on this, I mean the RPM will stay at 1100 rpm until the car "warms up" and you can mash the gas pedal and it won't touch the RPM even the slightest, it'll sit unoperatable for like 5-10 minutes before it "warms up". Weirdly enough this only happens when its below 10 degrees celsius outside. I've checked VCDS and have no faults in any control units, the VCDS reads the accelerator pedal position sensor being actuated perfectly fine from 0-100%, also shows "throttle position" at 95%, compared this to a known good car and it looked the same. Apparently the throttle position sensor is built into the gas pedal so I threw a new gas pedal in it just on a whim since the other was original and super old, nothing changed. A couple other weird things can be seen, my EGT will randomly spike to 1100 degrees while cruising at highway speeds (+100 km/h) (could be an issue with the gauge maybe unrelated), and finally, sometimes when pulling off from a standstill, example like turning in a busy intersection, it feels like the car will randomly like maybe 40% of the time go into limp mode and drive super slow like it's barely pulling its own weight, once again though, no dash lights, no fault codes, nothing. then it suddenly after like a minute or so once I'm halfway in the intersection about to cause an accident, it'll pop right back to behaving normally. other than these issues the car drives totally normal and after the car has warmed up once in the morning the other times i start it throughout the day may or may not trigger the "Dead pedal start".
The previous owner provided me with a receipt showing the turbo, intake manifold, egr system and throttle body had all been replaced in 2015 at 305k kilometres odo. and i bought it at 320k. I've done a lot of work on the car since owning it, like replaced all vacuum lines, new n75 valve, replaced all filters, brake light switch, clutch switch, removed the EGR system, changed exhaust and got a malone stage 1.5 tune done. I don't know for certain but after checking everything on VCDS and seeing that everything looks normal, I think the tune may be causing the issue, but the guy that originally did it basically disappeared. It was done at a reputable shop and I had no issues with it last winter, it seems like it happened after disconnecting my battery when I did my clutch and I didn't notice until the weather got cold enough, but that could just be a coincidence. Since it happened I applied vacuum to the turbo actuator and it seemed to move freely, checked the ASV, its working fine, checked all vacuum lines, no leaks, checked MAF plausibility in VCDS. The only slightly weird thing in VCDS is that my specified boost pressure is about 50 mBar more than my actual, compared with my friends working tdi his is about 20 mBar off, could it be that my actuator needs adjustment and maybe the car is triggering limp mode from overboost as soon as I touch the gas and with the high idle this cuts the throttle?
I've contacted someone else who's going to revert it to a factory tune after the holidays, but I was wondering if anyone else has any ideas if this does not fix the issue, or any insight on anything else to check that I may have missed. Thanks in advance and sorry for the long read lol
My car is a 2005 Jetta Wagon with BEW, 380k Kilometres on the odo, basically after 3 years of ownership it started doing this thing where on a cold start the gas pedal won't work at all, to elaborate on this, I mean the RPM will stay at 1100 rpm until the car "warms up" and you can mash the gas pedal and it won't touch the RPM even the slightest, it'll sit unoperatable for like 5-10 minutes before it "warms up". Weirdly enough this only happens when its below 10 degrees celsius outside. I've checked VCDS and have no faults in any control units, the VCDS reads the accelerator pedal position sensor being actuated perfectly fine from 0-100%, also shows "throttle position" at 95%, compared this to a known good car and it looked the same. Apparently the throttle position sensor is built into the gas pedal so I threw a new gas pedal in it just on a whim since the other was original and super old, nothing changed. A couple other weird things can be seen, my EGT will randomly spike to 1100 degrees while cruising at highway speeds (+100 km/h) (could be an issue with the gauge maybe unrelated), and finally, sometimes when pulling off from a standstill, example like turning in a busy intersection, it feels like the car will randomly like maybe 40% of the time go into limp mode and drive super slow like it's barely pulling its own weight, once again though, no dash lights, no fault codes, nothing. then it suddenly after like a minute or so once I'm halfway in the intersection about to cause an accident, it'll pop right back to behaving normally. other than these issues the car drives totally normal and after the car has warmed up once in the morning the other times i start it throughout the day may or may not trigger the "Dead pedal start".
The previous owner provided me with a receipt showing the turbo, intake manifold, egr system and throttle body had all been replaced in 2015 at 305k kilometres odo. and i bought it at 320k. I've done a lot of work on the car since owning it, like replaced all vacuum lines, new n75 valve, replaced all filters, brake light switch, clutch switch, removed the EGR system, changed exhaust and got a malone stage 1.5 tune done. I don't know for certain but after checking everything on VCDS and seeing that everything looks normal, I think the tune may be causing the issue, but the guy that originally did it basically disappeared. It was done at a reputable shop and I had no issues with it last winter, it seems like it happened after disconnecting my battery when I did my clutch and I didn't notice until the weather got cold enough, but that could just be a coincidence. Since it happened I applied vacuum to the turbo actuator and it seemed to move freely, checked the ASV, its working fine, checked all vacuum lines, no leaks, checked MAF plausibility in VCDS. The only slightly weird thing in VCDS is that my specified boost pressure is about 50 mBar more than my actual, compared with my friends working tdi his is about 20 mBar off, could it be that my actuator needs adjustment and maybe the car is triggering limp mode from overboost as soon as I touch the gas and with the high idle this cuts the throttle?
I've contacted someone else who's going to revert it to a factory tune after the holidays, but I was wondering if anyone else has any ideas if this does not fix the issue, or any insight on anything else to check that I may have missed. Thanks in advance and sorry for the long read lol