Howdy all you DI folk! Welcome to my first post in here.
A friend has a 2003 golf TDI, with the following issue:
Regardless of engine temperature, it feels like the turbo doesn't spool on the
first acceleration after engine start until the rpm has exceeded 2500. After the first time it passes 2500, it behaves normally in every way.
A local 'vw specialist' shop (the same one who's timing belt change on another friend's 2006 PD golf lead to total destruction of the head) said the computer noted intermittent MAF readings. They put a 'known good' maf in with no change in results.
Quite frankly, I'm going to start from scratch with troubleshooting, as this other shop is nothing but a cage full of monkeys to me.
I would like to know if anyone here has experienced anything similar, and what might have been a fix for it.
Thanks!
Dr. (IDI)D.
Odd, I'd start by checking the vnt actuator to make sure it is moving freely and that there are novac leaks in the hose running to it.
You can reach down behind the intake mani and move the actuator up and down by hand, there is a fair bit of spring tension on it, but it should move smoothly.
thanks!
I don't think it's the actuator itself. After the first time it exceeds 2500 rpm, it behaves normally. so, like no boost for the bottom of 1st gear, but fine from then on, including the following times in 1st gear. odd.
thanks!
I don't think it's the actuator itself. After the first time it exceeds 2500 rpm, it behaves normally. so, like no boost for the bottom of 1st gear, but fine from then on, including the following times in 1st gear. odd.
If the car is warmed up, then shut off and started again while still warm does it still have no power till it exceeds 2500 RPM?
That is, does it happen after every start? Or only the first start of the day?
I've never seen it personally, but it sounds like turbo "stiction"... the turbo bearings stick as the turbo cools down and it takes some air velocity on the warm-side turbine to overcome the internal friction... after which the turbo spins normally.
Common on old hard drives back in the day with sleeve bearings.
Vag-Com plotting boost etc during a test run might be worth looking at.
engine temperature plays no role whatsoever.
Stiction, eh? hm. occurs with age and bearing coking. I could probably verify that by giving the shaft a little spin by hand. But still, why? Fire it up, no boost till after 2500 first time. Then fine. Shut it off and immediately restart, try again, same thing. I'll see if I can find someone with a VAG and some know-how.
Thx!
engine temperature plays no role whatsoever.
Stiction, eh? hm. occurs with age and bearing coking. I could probably verify that by giving the shaft a little spin by hand. But still, why? Fire it up, no boost till after 2500 first time. Then fine. Shut it off and immediately restart, try again, same thing. I'll see if I can find someone with a VAG and some know-how.
Thx!
what if you shut off the engine and restart, does it need to hit 2500 again?
Hmm, that's a tough one. Sounds like a sticky turbo, the only reasoning I have behind that is when the car is shut-off, the N75 returns the vanes to the full open mode, farther than it would go just at idle. If there is enough carbon build-up in there, it will take a bit more oomph to snap them free of the carbon, upon which they return to the normal "open" mode when the car is at idle, which allows them to close during normal driving and boost requirements.
Doesn't really sound like a MAF or N75 issue though stranger things have happened.
Brendan
There could be an issue with the EGR solenoid.It the egr doesn't close after light load then it will cause turbo lag and low power
Mabye disconnect and plug the vaccum hose to the egr and try it.could also be an issue with the egr valve sticking or not closing 100%.