2005 Jetta BEW lost some MPG's.

Local2ED

Member
Joined
May 28, 2009
Location
United States
TDI
2005 Jetta
I have a 2005 Jetta BEW automatic. 171,000 miles, maybe 2 YO timing belt, all stock. Maybe up to the last year or so I thought my mpg's were going down slightly.

I used to get high 30's to low 40's around town and mid 40's highway. This was always hand figured at every fill up. My last fill up, maybe 50/50 mixed driving was 31mpg.
All the usual things like filters have been changed with no improvement.

The car runs as good as it ever has with the exception of a very slight barely perceptible lag when accelerating at lower speeds.

The fuel injectors are original and never been touched. Could anybody recommend a fuel injector cleaner or at this mileage should they be serviced/replaced?

The brakes don't seem to be dragging as none of the wheels feel hot to the touch and all feel pretty much the same temp. I have a temp. gun to check them but they all feel fine so I didn't see a reason to.

Does any of this indicate EGR problems, camshaft wear, etc.?

Also while I haven't scanned it , it shows no CEL.

Thanks.
 

DuraBioPwr

Veteran Member
Joined
Jan 28, 2020
Location
Eastern Washington
TDI
2004 BEW Jetta (5spd)
Your intake might be crudded up due to the EGR. Your auto tranny may be slipping and or not locking up the torque converter. Injectors should be fine at that mileage. Mine have 275K on them and working fine. You could try to clean injectors but prob wont help with your mileage decline.
 

IndigoBlueWagon

TDIClub Enthusiast, Principal IDParts, Vendor , w/
Joined
Aug 16, 2004
Location
South of Boston
TDI
'97 Passat, '99.5 Golf, '02 Jetta Wagon, '15 GSW
You can run a can of diesel purge through the engine to clean the injectors. I believe there's a how-to on doing that here. Run the engine directly on the diesel purge, don't add it to the fuel tank. And checking the EGR/intake for carbon build up is a good idea.

I'd also suspect the actuator on your turbo is worn out, causing the lag you experience and the reduction in FE. It could be something else in the vacuum system (N75, vacuum hoses) but the actuators on the turbos do fail over time, and yours if 15 years old, assuming the turbo is original. Find someone to run a boost log to confirm. And also look for any fault codes that might point to something else in the system, if it's not the actuator. Just because you don't see a CEL doesn't mean there's not a stored fault.

Unfortunately the actuator for your turbo is available separate from the turbo. So if it's shot a new turbo is your option. That's why you want to be sure that's the problem.

You can also check for boost leaks. Common places on BEWs are the connection from the upper intercooler pipe to the EGR valve and the lower connection to the intercooler (under the car).
 

Local2ED

Member
Joined
May 28, 2009
Location
United States
TDI
2005 Jetta
Your intake might be crudded up due to the EGR. Your auto tranny may be slipping and or not locking up the torque converter. Injectors should be fine at that mileage. Mine have 275K on them and working fine. You could try to clean injectors but prob wont help with your mileage decline.
Watching the tach it doesn't look like the trans is the problem.
Thanks.
 

Local2ED

Member
Joined
May 28, 2009
Location
United States
TDI
2005 Jetta
You can run a can of diesel purge through the engine to clean the injectors. I believe there's a how-to on doing that here. Run the engine directly on the diesel purge, don't add it to the fuel tank. And checking the EGR/intake for carbon build up is a good idea.

I'd also suspect the actuator on your turbo is worn out, causing the lag you experience and the reduction in FE. It could be something else in the vacuum system (N75, vacuum hoses) but the actuators on the turbos do fail over time, and yours if 15 years old, assuming the turbo is original. Find someone to run a boost log to confirm. And also look for any fault codes that might point to something else in the system, if it's not the actuator. Just because you don't see a CEL doesn't mean there's not a stored fault.

Unfortunately the actuator for your turbo is available separate from the turbo. So if it's shot a new turbo is your option. That's why you want to be sure that's the problem.

You can also check for boost leaks. Common places on BEWs are the connection from the upper intercooler pipe to the EGR valve and the lower connection to the intercooler (under the car).

Not sure what a boost log is or where to look for somebody who can run one.

Autozone has a scanner that shows live data, would that be OK to check for a stored fault or does it have to be Vagcom or whatever that is called?

Thanks.
 

IndigoBlueWagon

TDIClub Enthusiast, Principal IDParts, Vendor , w/
Joined
Aug 16, 2004
Location
South of Boston
TDI
'97 Passat, '99.5 Golf, '02 Jetta Wagon, '15 GSW
Scanner at Autozone won't tell you what you need to know. Where are you located? Maybe there's a guru that's not too far away.
 

Terrific-In-Tahoma

Veteran Member
Joined
Jun 4, 2012
Location
East-of-Toronto, Ontario, Canada
TDI
'01 ALH Jetta M5 / 05 BEW Jetta Wagon A4
From the signature of the original poster, they are somewhere in the United States.

That should narrow it down a bit. (At least they don't need the Bi-Lingual VCCS Software).

The best place is to search the |Trusted TDI Mechanic's Map} and go from there.
 

Tom Brown

Veteran Member
Joined
Apr 29, 2009
Location
Regina, SK, Canada
TDI
2001 Golf TDI, 2006 Jetta Wagon TDI
Clean the MAF sensor.

I use brake cleaner but others indicate this is the work of the devil and to only use MAF cleaner.

I have to do this about every 50K km (30K miles). It takes less than 5 minutes.
 
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