Fuel consumption and limp mode

Piet skiet

Member
Joined
Mar 14, 2023
Location
Alberton Jhb South Africa
TDI
Jetta 4 1.9tdi
Hi guys I recently bought a 1.9tdi jetta 4 overall its a lovely car to drive but I had a issue where we scanned it got some faults after all cleared and nothing came back I'm now seeing a higher fuel consumption as the car idles and heats up it goes to 6.9liters per 100km from 6.3 literally as I watch it climb, also had it go into limp mode turbo not boosting after a certain speed which it hasn't done before what would the most common issue be on this? Thank you in advance
 

braddies

Veteran Member
Joined
Jul 26, 2021
Location
America
TDI
03 golf ALH
19 year old rubber vacuum lines are suspect they get brittle crack and leak, I'd start by checking/replacing the line that runs from the turbo actuator to the N75 valve, maybe replace them all but be careful removing them because the plastic nipples are easy to break
 

Piet skiet

Member
Joined
Mar 14, 2023
Location
Alberton Jhb South Africa
TDI
Jetta 4 1.9tdi
19 year old rubber vacuum lines are suspect they get brittle crack and leak, I'd start by checking/replacing the line that runs from the turbo actuator to the N75 valve, maybe replace them all but be careful removing them because the plastic nipples are easy to break
Hi thanks for the reply I replaced all yesterday and still the same though it starts off showing not too bad l/100km as I let it warm up and climbs rather quickly also been seeing some smoke from the exhaust when the car is cold and none when its warm
 

braddies

Veteran Member
Joined
Jul 26, 2021
Location
America
TDI
03 golf ALH
What did you get for codes? Do you have a liter/100kilometer on the instrument cluster?
 
Last edited:

braddies

Veteran Member
Joined
Jul 26, 2021
Location
America
TDI
03 golf ALH
Nice cluster, mine just tells me when the doors are open.
There's a limp mode troubleshooting thread around here somewhere with tons of good info... still looking for the link to that.
if you're getting an under boost code you might try making sure the turbo actuator moves freely (by hand) and with vacuum applied.
A Mityvac is great for measuring vacuum, you can connect it to the vac line right off the vac pump and see what the vac pump is making, should be 25-30hg at the pump. Low vacuum could cause your symptoms but any more info you have could be helpful
 

Piet skiet

Member
Joined
Mar 14, 2023
Location
Alberton Jhb South Africa
TDI
Jetta 4 1.9tdi
Nice cluster, mine just tells me when the doors are open.
There's a limp mode troubleshooting thread around here somewhere with tons of good info... still looking for the link to that.
if you're getting an under boost code you might try making sure the turbo actuator moves freely (by hand) and with vacuum applied.
A Mityvac is great for measuring vacuum, you can connect it to the vac line right off the vac pump and see what the vac pump is making, should be 25-30hg at the pump. Low vacuum could cause your symptoms but any more info you have could be helpful
Awsome thank you I'll have a look into the turbo thank you for the help I appreciate it
 
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