Hi all, After spending over a month and a fortune on my gti, I now concede to the internet and ask for help haha. It’s an 06 gti with a bwa. I’ve replaced maf, n75, checked map voltage on a scale and that’s correct with no spikes, new pcv, all boost pipe seals, checked and re-checked fitment of everything, tried without 1st lambda to rule out blocked cat, without air filter to rule that out and also even taken the pipe off the actuator from n75. Whatever I do, I can’t get more than 0.7 bar spike settling to 0.5! If I push the throttle gently to the floor I get 0.3, if I go from no throttle to full quickly I get the above 0.7-0.5 held. Car is averaging 24mpg and is down on power, obviously. No fault codes present and no lights on dash. Maf at wot goes to a max of 108g/s near redline and fuel pressure shows at 1550 psi so around 105 bar. I’ve even pulled the whole front of the car off to check the intercooler but still nothing! Basically at my wits end with it now and have no More money to throw at it either! I’ve been a tech for 12 years and understand how the system works etc, just can’t see what could be causing it now. It would also seem based on the sound, the the ecu is opening the dv sometimes too for some reason? Not sure why as it never even gets to standard boost and it’s supposed to be stage 1 mapped. If there’s anyone with either some suggestions, or local with vcds that could do some logging that would be awesome! I have some scan tools but they’re not as involved as vcds so I can’t log dc, afr and fuel tank pump pressure duty etc. I’m on the south coast near Hastings. Thanks all.
Did you replace the turbo diverter valve? Very common fail, lots of people change them regularly as a matter of course.
Hi, thanks for your reply. The car came fitted with a new rev d diverter. I then fitted a new oem rev g to rule it out and still no different unfortunately.
Cool, thanks. I tried winding it up a little which made it spool a bit faster but no other change. I even took the pipe off the actuator and still didn’t see more than 0.7 bar? I think the car needs logging now as I can’t spend any more and can’t work out where to go from here lol. I’ve even spoken to Ben at R-tech and he was passing my email to Nick to read and come back to me. Just at a loss with it now. Had it over a month, spent all my backup money on it to get nowhere, and now rapidly going off the car. Had a mk5 gt tdi 170 with a map years ago which I loved, just want this one to go as it should so I can enjoy it lol.
That’s what I expected but still only 0.6 bar. From what I’ve learnt the ecu can open the dv if it feels it needs to? This is what I think is happening as the hiss I get under load comes from the same place as the small dv hiss on letting off. Using the 5v reference signal to the map, at 14.7 psi atmospheric pressure as reported by the ecu, I’m pretty sure I should be seeing 2v at the map? Rising 1v per 0.5 bar of boost to utilise the 5v scale? What is odd is ignition on, key off the map gives me 1.79 volts. If this is under reading the ecu and map readings won’t match and I’m guessing the ecu will open the dv and refuse to use the n75 which would make sense. Thing is, I can’t find a scale or anything to compare with for map voltages anywhere so all I can do is use the 5volt reference and convert it to the 2.5 bar of the map sensor at 1 volt per 0.5 bar. That would make 2 volts at sea level but doesn’t. Normally I know these cars give a code for map signal implausible but for some reason it took over a days driving to work out I’d unplugged the maf when testing it so I resorted to manually testing stuff. Just wish there was someone nearby with vcds. Think I could log it and solve my issues in half hour lol!
Worth asking on the club gti Facebook group for someone with VCDS? https://www.facebook.com/groups/clubgti/ All sounds like the turbo itself to me as with no ECU control it still won't boost high.
I was worried it might be the turbo but wasn’t sure if it was just dumping the boost via the dv. That’s what I’m hoping for as can’t afford more parts just yet and if I’m swapping it, I’d probably use it as an excuse to go k04 haha. Thanks for the link, I’ll pop on there and see if anyone can help
May as well upgrade if it is the case of a worn turbo. K04 mapped make a quick car, my ED30 goes well.
Once I get this one right I may well sell it and go after an ed30 or at least a dsg car. The manual is great but I’m getting old and lazy
