turbo lag? or my imagination? remapped TDI

[david burton]

Hi,

I've tried other forums for TDI tuning help to no avail, no-one seems to have experienced what I seem to be seeing in my TDI..... although I've just stuck to VW forums so maybe that's the problem

A bit of background: I've got a remapped 1.9 TDI PD100 Polo. Other mods include a green cotton filter and PD160 intake. Nothing else. I expect an output of around 125-130bhp.

I've got a video after the remap of 30-70 in 3rd showing about 8.5 seconds.

Now the problem: I seem to suffer from a lot of turbo lag recently. It appears to be worse under full throttle or redline gear changes. We're talking a second or more of lag under redline conditions, and no turbo surge whatsoever if I floor it at 1500rpm - not even once it gets to 3000rpm.

Normally I would expect half a second of lag at high rpm gear changes. And at low rpm I'd hope for a surge of boost at just under 2000rpm.

What could be causing this? There are no obvious boost pipe splits, I've tried disconnecting the MAF with no changes, cleaned the MAF, and run injector cleaner through it. Some days seem worse than others.

Also, is there a way to reduce lag at redline changes? Something to keep the turbo spinning that bit faster? Am I on a hiding to nothing until I fit a boost gauge?

Any help is much appreciated, I've been searching the forums and there are posts out there, but no real answers.

Thanks.

 

[john2017]

lag

Hi David,

May I ask who remapped it?
It's difficult to find a company with the right knowledge.
One of these companies is allards and it might be worth speaking with them.
I had pd100 fabia with fmic and pd130 injectors and remap - 180 bhp 300 lb ft with less lag than standard. Perhaps VAG Com data might show the weakness?
Cheers

Hi,

I've tried other forums for TDI tuning help to no avail, no-one seems to have experienced what I seem to be seeing in my TDI..... although I've just stuck to VW forums so maybe that's the problem

A bit of background: I've got a remapped 1.9 TDI PD100 Polo. Other mods include a green cotton filter and PD160 intake. Nothing else. I expect an output of around 125-130bhp.

I've got a video after the remap of 30-70 in 3rd showing about 8.5 seconds.

Now the problem: I seem to suffer from a lot of turbo lag recently. It appears to be worse under full throttle or redline gear changes. We're talking a second or more of lag under redline conditions, and no turbo surge whatsoever if I floor it at 1500rpm - not even once it gets to 3000rpm.

Normally I would expect half a second of lag at high rpm gear changes. And at low rpm I'd hope for a surge of boost at just under 2000rpm.

What could be causing this? There are no obvious boost pipe splits, I've tried disconnecting the MAF with no changes, cleaned the MAF, and run injector cleaner through it. Some days seem worse than others.

Also, is there a way to reduce lag at redline changes? Something to keep the turbo spinning that bit faster? Am I on a hiding to nothing until I fit a boost gauge?

Any help is much appreciated, I've been searching the forums and there are posts out there, but no real answers.

Thanks.

 

[ini]

Maybe the VNT actuator rod adjustment nut is not tight?

You could try altering the length.

A boost gauge is vital for messing with the vane opening, but altering it in half turns should be good.

 

[david burton]

Thanks guys, the first real responses I've had to this situation.

The remap was done by a guy with the username "RichardBW" over on UK-Polos. He works for another tuning company and was offering remaps at GTI International. Another member or two had already used him with very positive results. It's not an aggressive remap but knocked 2 seconds off the 30-70 time.

I like the actuator rod analysis. This is the rod round the back of the engine to control the turbo? - it's definitely free moving as I've looked at it already. I didn't realise it was adjustable.

If it helps, the car has done around 28k miles.

I think I'll invest in a boost gauge too - are some easier to fit than others?

Cheers.

 

[sssstew]

David

Youve come to the right place

If i were you i would get vag com on it and do some logging, check the MAF and Boost, Requested vs Actual. This will tell you if the MAF or turbo is at fault, or if its a boost leak etc. Otherwise we are kind of guessing. Its recommended to fiddle with the VNT rod without a boost guage, its just likely to go into limp mode.

 

[david burton]

Thanks mate,

I'm trying to find a relatively cheap place with the VAG-COM software. I know a couple of the guys at True-Tec near Reading - they sponsor my forum, but not well enough to take the piss..... plus I don't think they know VAG-COM in and out so it becomes tricky.

RichardBW said he'd guide me through a MAF test if I could get hold of VAG-COM but it felt a bit awkward so I never took him up on the offer.

One thing to note - it has hit limp mode once a month over the last few months. However it's once every 2000 miles or so.

I'll check out the actuator rod tomorrow in the daylight and see if anything is loose - I presume that the spring will always hold in in tension so I won't be able to tell if it's at the right setting straight away?

 

[devonmikeyboy]

I know Richard and he is a very honest bloke and a very good mapper. Can you not find anyone local who has VAGCOM to check your car over?

 

[sssstew]

if you have access to a laptop then it might be worth investing in a cable and the software.

 

[david burton]

I know Richard and he is a very honest bloke and a very good mapper. Can you not find anyone local who has VAGCOM to check your car over?

I agree, he seems like a good guy and was very willing to help out.

 

[david burton]

I know Richard and he is a very honest bloke and a very good mapper. Can you not find anyone local who has VAGCOM to check your car over?

Hi,

there are a few links on the uk-mkivs site to people who would be willing to help out with VAG-COM. I guess the best thing to do would be to contact one of them and see if they are proficient enough to diagnose turbo / maf problems.

No laptop I'm afraid, so can't go down that route.

 

[david burton]

I think I found the problem - the pipe from the control unit to the actuator (vacuum pipe?) seems like it's caught on the exhaust and perished.

how easy is it to replace?! and should it be routed between the exhaust and the intake pipe? it looks like it shouldn't!

 

[sssstew]

the small vacuum pipe should be cliped on to the larger pipe going down to the actuator. i cant see properly in your pic though. Not too bad to replace but getting it off the ends is usually tough as the rubber gets old and hard.

 

[david burton]

I think that's the larger pipe - there's only one pipe I can see going from the control until round the back of the engine to the turbo. It's about 8-10mm in diameter I guess. I have no idea why it's routed here because it's so close to the exhaust recirculating pipe. Here's a better picture to explain the route of the pipe. I have no idea how this pipe removes from the control unit.

p.s. I wasn't actually testing the actuator - I was testing the EGR system actuator. Sigh.

 

[david burton]

anyone know if the above mentioned pipe is anything to do with the turbo?

 

[sssstew]

i dont recognise it as my pipe routing is different on my ibiza, so cant immediatly help....