Turbo problem when starting from cold

[khampson]

My Seat Leon 1.9 tdi SE has a fault of some kind when I start up the car
from cold it is fine until I reach about 70 mph the turbo cuts out and does
not work until I switch the car off then its fine it works fine up to 70mph (as long as its warmed up), it only does it when starting from cold the outside temp was 10 c though. if the engine is warm then no probs, but I not sure if it as actually the turbo that's faulty or something else to do with it. because when I switch the car off it resets the problem and works fine. any suggestions as to what it could be?

 

[techie]

Its shutting off due to an overboost fault. Usual culprit is the variable vanes in the turbo. They get seized up due to soot in the exhaust housing. This means it just gets to much boost and the ECU shuts it down to protect it.

But this fault can also be caused by a faulty N75 valve or a kinked vacuum pipe to the valve.

 

[khampson]

But how come it only does this when the engine is cold, I have no problems at all when it is warmed up, if I took this to a dealer would it be an exspensive problem to fix? do I need a new turbo? or does it want cleaning or something?

 

[Neo_VR]

I have a very similar problem..

my turbo "holds back" on boost until it hits 2500rpm... it smokes like a mofo when this is happening too, never found the culprit.. and its fine when its warmed up

 

[muddyboots]

Guess it's something to do with expansion & changing clearances of various parts as they warm up ?

 

[basstard]

it goes limp mode so the ecu will have to show up something, get vagcom or get it scanned by someone with it. Or go to the dealer as a last resort [ ].

After that, post the error here,,, [ok, I can't assure you nothing ]

techie, I bow to your knoledge, but then it only does it when cold,,, so I don't think it's sticky vanes or shot N75,,,

 

[Sisson]

whats the best way to free up the variable vanes in the turbo?

mines doing it at the min, im having the boost on my remap knocked down a bit to stop it doing it but will it cure it?

cheers

 

[basstard]

clever way: floor the f*cker every now and then from new so that the vanes work all the time and don't get sticky.

richman way: once they're stuck get the turbo off and get it cleaned, refurbed and balanced

lazyass way: buy some spray cleaner and spray it after the maf into the inlet with engine running at 2000/2500 rpm [in neutral!!! ]. This is supposed to clean the IC, EGR, boos pipes, inlet, head ports and valves too,,, wheter this works and how much effect it has remains to be seen but I've seen more than one turbo freed up, so, at least for the sticky vanes, this works,,,

 

[dmjw01]

whats the best way to free up the variable vanes in the turbo?

Not sure how easy it is to cure it once it's happened, but the preventative "maintenance" is to give the engine a thorough spanking once in a while. Third gear, full throttle from 2000 to at least 4500 rpm should do the trick - joining the motorway on an uphill sliproad is ideal. This makes the engine request full boost, and exercises the guide vanes. Do this at least once a week when your engine's fully heated up, especially if you've been stuck in a lot of traffic queues recently.

 

[Sisson]

i drive like that anyway, im having the remap changed today so hopefully it won't do it,

what does the actuator do?,

because the bloke that chipped it for me, tweaked it a little and it hasn't gone into limp mode since but the turbo doesn't seem as powerful as before? Will it have made my car slower?

cheers

 

[basstard]

I hope he didn't touch the screw on the actuator arm,,,

Boost pressure with these turbos should be controlled via ECU alone IMHO. Whatever happens, DON'T TOUCH THE ACTUATOR ADJUSTING NUT

 

[dmjw01]

It's entirely possible that you don't have a sticky turbo at all - it could just be that your remap was a little bit too aggressive with the boost. Could just be that the colder intake temperature on startup tips your boost over the threshold.

 

[basstard]

why cold temps should make the boost higher??
More oxygen per same volume [denser air] but not higher boost IMHO.

 

[Sisson]

it seems to go into limp mode at any temp,

i think he did touch the actuator nut, he turned it one thread one way which made it worse and then 2 threads in the opposite direction and it made it better, but it still overboosts, should i turn the actuator nut back to normal?

 

[basstard]

YES!! Get rid of that "tuner",,, if he doesn't even know which direction to turn the nut and does it so light heartedly I think he hasn't got a clue.

When turning the arm nut, always put a mark to remember the original position,,,

 

[Sisson]

Which way am i meant to turn it? anti- clockwise or clockwise or should i get the garage to do it,
in all fairness the garage is very good, he was seeing if the actuator had been played around with before i had the car, when i go for the remap ill ask them if they put it back to normal???

 

[dmjw01]

why cold temps should make the boost higher??

You're right. It's gonna make the charge mass higher, but not the pressure. It's too early in the morning for me!

 

[basstard]

Which way am i meant to turn it? anti- clockwise or clockwise or should i get the garage to do it,
in all fairness the garage is very good, he was seeing if the actuator had been played around with before i had the car, when i go for the remap ill ask them if they put it back to normal???

Ask the guy who chipped it,,, or better yet, ask someone like prc in here. I don't know, and that's the reason I don't play with that stuff,,,
Don't get the garage to do that unless you are in friendly terms with them. Sod the garages, DIY and log the boost pressure via vag com. what car is yours?

 

[Sisson]

its a ibiza pd130 with custom code phase 1.

the garage did 4 test runs and at about 4k+ revs, the car was overboosting,

iv just been on the phone to the garage and he said he tweaked the actuator one way and made it worse and then put it back to normal again, custom code are changing the software to back to boost off a touch at high revs and maybe alter the tolerances as well, im not sure, any way, the software should be ready by tomorrow, so hopefully no more limp mode.

i haven't got vag com, yet.

 

[prc]

IIRC counter-clockwise will make the vanes move quicker (less overboost).
moving the actuator arm around is best left to proper turbo techs, with the right equipment.

Most tuners keep the factory tolerance of +-0.3bar. If this is altered you probably won't get your limp mode fault, but again the root cause of the boost fault should be found.