Hesitation on 110 TDI

[tony19b]

My Tolly 110TDI has developed a strange sort of hesitation- if I accelerate smartly in 2nd but then have to ease off slightly there is a pronouced "cough" or hesitation, sometimes two or three in succession. Otherwise the car goes like a train, apart from the odd limp mode, which seems to be common on this engine. Has anyone else experienced this, and could it be something that will need attention?

 

[aaronbromley]

I would strongly advise having the car checked out with some diagnostic software (VAG-com), hopefully this could point you in the right direction).

 

[sssstew]

yeah the limp mode will have a fault logged so see what that is then go from there. Likely to be the turbo vanes which are sticking.

 

[tony19b]

I had the car checked out by a Seat dealer whilst on holiday a couple of years ago. The diagnosis was: 17965 P1557 035-boost pressure regulation control limit exceeded. The recommendation was to replace the turbocharger! I did not have anything done, and 25000 miles later it's no worse, and responds to the "Italian tune-up" technique recommended elsewhere on here. So sticky vanes it very likely is. However the new problem doesn't trigger limp mode, after the momentary hesitation the car will accelerate normally. I use V power diesel and Miller's, maybe I should put a couple of spoons of Veno's in there too!

 

[sssstew]

could quite possibly be EGR related, i used to have a part throttle turbo stutter from mine when i had a dodgy EGR control valve. You could try swapping the N18 and N75 valves on the back firewall and see how it goes.

 

[asthpsw]

What is "Italian tune-up" technique ?

I get two types of Limp mode....the one we all know & love where its like we have a normal Turbo charger & the lower power...............but I sometimes get one that is like a "semi limp" mode that you feel a loss of power after hesitation or more frequently I've been driving along at a constant speed on the M27 then when I try to accelerate its lost some of its poke..............then I turn off, back on & its OK again................I did read in a VW techincal article there is a couple of different safe modes depending on what triggers it..........I'll have to try & dig out the article tonight.

Paul

 

[S3 AKR]

What is "Italian tune-up" technique ?

isn't that where you just cane the crap out of the car and hope that any blockage goes away ?!!

 

[tony19b]

That's the one, give it a good ragging, preferably up a long fast hill, get the turbo hot.

 

[tony19b]

could quite possibly be EGR related, i used to have a part throttle turbo stutter from mine when i had a dodgy EGR control valve. You could try swapping the N18 and N75 valves on the back firewall and see how it goes.

That sounds like a strong possibility- will get these replaced, cheers.

 

[sssstew]

dont need to replace yet, swap them over as they are the same internally, that way you can identify if one is dodgy, thats how i identified it was my N18 EGR control valve that was causing my turbo stutter and not the N75 boost control valve which would have been more logical.

 

[tony19b]

Ah I get it! Will have a go this weekend and see what happens- cheers!

 

[asthpsw]

[
I get two types of Limp mode....the one we all know & love where its like we have a normal Turbo charger & the lower power...............but I sometimes get one that is like a "semi limp" mode that you feel a loss of power after hesitation or more frequently I've been driving along at a constant speed on the M27 then when I try to accelerate its lost some of its poke..............then I turn off, back on & its OK again................I did read in a VW techincal article there is a couple of different safe modes depending on what triggers it..........I'll have to try & dig out the article tonight.

Dug out the article & it defines what I think are two types of "Safe mode" & although these safe modes are related to the failure of sensors I wondered if either of the two "Safe modes" could appear because any of the sensors were picking up "problems"

What the article says :

If charge pressure sensor fails then the vanes are adjusted to a Steep Angle

If altitude sensor fails then the Constant output turbocharger is mapped

I think I get the first one when I get over boost & find I get the latter one if I go for miles (motorway...maybe with the cruise control on) at a constant RPM then suddenly try to accelerate (even gentle) & there isn't anything there but its not like normal limp mode.

Paul