ALH Bad Mileage

Hussman

Well-known member
Joined
Aug 8, 2018
Location
Crosslake, Minnesota
TDI
2003 VW Jetta ALH TDI 5 speed
Hey guys, So obviously there has been a ton of posts about bad mileage, and I've read a ton of them. All highway driving I'm getting 39-41 MPG with My ALH manual Jetta that has 175k on it. I bought it from a doctor who bought it brand new in 2003. He was very anal and has every single receipt for everything that ever was replaced or fixed on the car.

Since I've bought it...

New air filter
New fuel filter
New cabin filter
New N75
Malone stage 1 tune
Cleaned Intake manifold
unplugged EGR after clean
CAT delete
full bottle of diesel kleen

I got a scan gauge and the temp never went over 168 on the scan gauge, and the stick on the dash struggles to get and stay at 190f. So I have a Kerma Tdi thermostat coming to run at 194f. Do you think running 161-167 for temp would be enough to cause such poor mileage?

I also have a bottle of Diesel Purge coming to try that.

Is there anything I'm missing?
 

Hussman

Well-known member
Joined
Aug 8, 2018
Location
Crosslake, Minnesota
TDI
2003 VW Jetta ALH TDI 5 speed
Yup,
It gets fueled more heavily with lower engine temps.


Do you think that’s hurting me all 10 mpg? I mean my first 2 tanks were 49-50.5 and now I’m way down. Do you think I need a temp sensor too? Because the stick said I was at 190, but my scan gauge said 161.


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oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
Read through my sticky at the top of the Fuel Economy section. I tried to make as comprehensive of a collection of the sorts of things that can ding fuel economy.

edit: I see someone already beat me to it! :)
 

Hussman

Well-known member
Joined
Aug 8, 2018
Location
Crosslake, Minnesota
TDI
2003 VW Jetta ALH TDI 5 speed
Read through my sticky at the top of the Fuel Economy section. I tried to make as comprehensive of a collection of the sorts of things that can ding fuel economy.

edit: I see someone already beat me to it! :)


I’ve read that post a few different times, thanks for it, it is helpful.


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phaser

Veteran Member
Joined
Apr 18, 2004
Location
Oregon
TDI
2004 Jetta PD - 490k
Recently, my 14 year old top turbo hose to the egr had a blowout in the rubber wall.

In checking all the connections in the high pressure path, I found all of the joints to be loose due to wear on the seals and aluminum locking barbs. All the joints had oil crud blow by accumulation when separated for inspection.

Replaced the upper hose and the hose from the pancake pipe to inter-cooler. This resulted in an immediate mpg increase of 3.6mpg, over the usual 48. The blowout dropped it down to 44mpg.

Will be replacing the high pressure hose coming off the turbo to the pancake pipe as soon as it comes in.

.
 
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hugho

Active member
Joined
Feb 17, 2018
Location
NW wyoming
TDI
red 2002 vw Jetta wagon 250K miles, MT
Hey guys, So obviously there has been a ton of posts about bad mileage, and I've read a ton of them. All highway driving I'm getting 39-41 MPG with My ALH manual Jetta that has 175k on it. I bought it from a doctor who bought it brand new in 2003. He was very anal and has every single receipt for everything that ever was replaced or fixed on the car.

Since I've bought it...

New air filter
New fuel filter
New cabin filter
New N75
Malone stage 1 tune
Cleaned Intake manifold
unplugged EGR after clean
CAT delete
full bottle of diesel kleen

I got a scan gauge and the temp never went over 168 on the scan gauge, and the stick on the dash struggles to get and stay at 190f. So I have a Kerma Tdi thermostat coming to run at 194f. Do you think running 161-167 for temp would be enough to cause such poor mileage?

I also have a bottle of Diesel Purge coming to try that.

Is there anything I'm missing?
Yes. New thermostat! We replace thermostats on our trucks, tractors and cars every other coolant flush even if they are working OK.Did anyone set the IQ on the pump? Diesel purge the injectors and use power service gray jug forever. If the injector tips are clean and not worn out the idle should be dead smooth and even after cleaning. If not, replace them. You should be getting 50+ mpg at a steady 55-60 with a MT.
 

PHOTOGUY1000

Veteran Member
Joined
Apr 9, 2012
Location
Canyon Lake, CA
TDI
2015 Golf S, SE & SEL & 2003 New Beetle
I have two of these 03 beetle & Jetta mixed highway & city 75 mph on freeway. Always get about 43mpg at least here in So California I have never seen the kind of mpg numbers I see on this forum my 98 Jetta was the same. So to me your not that far off.
 

Searcher2

Veteran Member
Joined
Oct 9, 2014
Location
Bossier City La.
TDI
'98 Beetle tdi
Same as Photoguy. I drive to get there as soon as I can with a 100 pounds + extra weight in the trunk and get 44 on the interstate. In town 33 to 35 but when I should be in 4th I'm usually in 3rd and have to try to remember to go to 5th on long stretches.
 

TornadoRed

Top Post Dawg
Joined
Aug 3, 2003
Location
West Des Moines (formerly St Paul)
TDI
2003 Jetta TDI wagon, silver; 2003 Jetta TDI wagon, indigo blue; 2003 Golf GL 5-spd, red (PARTED); 2003 Golf GLS 5-spd, indigo blue (SOLD); 2003 Jetta TDI wagon, Candy White (SOLD)
When my 2003 Golf TDI was new and then for the next 5+ years my fuel mileage average was barely 40 MPG. A little better in the spring and fall, worse in mid-summer.

At about the 5-year mark I got a different engine tune and fuel mileage improved a bit.

About a year later I moved from SoCal to the Midwest. I think the greater percentage of highway driving was the reason for a further increase in fuel mileage, with the average about 43 MPG. It was still a bit lower in the winter and summer than in the fall and spring. Bought a set of Michelin Defenders and fuel mileage dropped.

Then in 2014 I got a new VNT-17 and a new Malone tune, and fuel mileage improved immediately -- from barely 40 MPG to 43-45 MPG. Since I changed jobs in February 2017, with more highway driving, fuel mileage has been solidly in the 44-45 MPG range.

So, how to get better fuel mileage?
1) Make sure your injectors/nozzles are not worn out.
2) Upgrade your engine tune.
3) Drive more highway miles.
 

STDOUBT

Veteran Member
Joined
Jul 30, 2007
Location
Portland, effing Oregon
TDI
dos jettas
I got a scan gauge and the temp never went over 168 on the scan gauge, and the stick on the dash struggles to get and stay at 190f.
I've read here on tdiclub that the coolant temperature sensor can fail and not throw a code. Also, your reported temp at the instrument panel "the stick on the dash", is symptomatic of a failing coolant temperature sensor.
Much easier to replace than a thermostat too!
But strangely missing from oilhammer's fuel economy post.
https://www.idparts.com/coolant-temperature-sensor-green-oem-4pin-wseal-clip-a4b55-p-959.html
Pretty sure the scanguage is just going to report whatever the temp sensor tells it (which would be inaccurate if it's failing).
 

apple4ever

Well-known member
Joined
May 22, 2006
Location
Coatesville, PA
TDI
2002 Jetta TDI, 5sp manual, 280K miles
Looks like I'm having a similar issue. 43 MPG doing 55-60 on the highway, and the dash gauge usually has trouble getting up to "190".

I replaced my coolant temperature sensor back in 2015. I'm guessing its the thermostat this time. Good to know to check with my VAG-COM.
 

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
We're not all getting 50 mpg, many variables not least of which these cars are old.
I only saw 50 once in my old 99.5 Jetta, pure freeway 75mph, thru WV and TN. My old Jetta stock and later Stage 2, and my 03 Beetle both got low 40's mixed. Though the Jetta did high 40s for the first 50k.
 

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
Funny, my last fill (Sunday) was 50 MPG flat. No trips, mostly commuting, sometimes running at 80+ on the highway, some traffic, fair amount of suburban driving. My average for the last 158K miles is 46.2. Best is 52.2. I don't drive gently, but this car continues to give good numbers regardless.

My son's '02 Golf has 370K on it and has had very little work done on the car aside from a new set of nozzles last year and routine maintenance. Yet in August I drove the car fully loaded to Wisconsin, A/C on the whole time. We did run at 70 MPH because I was following my son's old truck and that's all it could manage, but that car got 50 MPG on that trip. As an aside, it had gotten a new thermostat just before the trip. So if you maintain the car the FE should be good.
 
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BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
So what's the key, owning a parts house?

Many of us get low 40s with properly maintained cars, so what's the key, worn injectors, cause it ain't maintenance.
From what I can read, roughly a third of us get that magic 50, some even higher.
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
I've gotten a lot of people through here that think they get bad fuel economy, and I drive the car for a few days, blow the filth out of it, fill it, drive it for another few days, and return it with a ~50 MPG (or whatever it should/could get) pen and paper calculated tank.

More often than not, I am sure that driving the car too easy for too long is what is causing MORE fuel consumption.
 

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
I think this is my best tank in IBW:


That included cruising across southern Ontario at 55-60 MPH on a cool day, so it was the best of conditions. I think that was the 52 MPG tank. But my average range over the last 150K miles is over 700.

I think oilhammer is right. These cars like to be exercised. I'll go 85-90 MPH when traffic is flowing at those speeds (not uncommon around here). My son drives his Golf hard all the time. Keeping the carbon out of the head and the turbo helps a lot.
 

apple4ever

Well-known member
Joined
May 22, 2006
Location
Coatesville, PA
TDI
2002 Jetta TDI, 5sp manual, 280K miles
We're not all getting 50 mpg, many variables not least of which these cars are old.
I only saw 50 once in my old 99.5 Jetta, pure freeway 75mph, thru WV and TN. My old Jetta stock and later Stage 2, and my 03 Beetle both got low 40's mixed. Though the Jetta did high 40s for the first 50k.
Oh of course, I'm sure there's a couple of other things that would help, including new injector nozzles (since I'm at 269,000 miles).

But I've already noticed the temp gauge not getting up to temp, so might as well as eliminate that as an issue.

Best I ever got was 53MPG, though that was 100,000 miles ago.
 
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Hussman

Well-known member
Joined
Aug 8, 2018
Location
Crosslake, Minnesota
TDI
2003 VW Jetta ALH TDI 5 speed
Oh of course, I'm sure there's a couple of other things that would help, including new injector nozzles (since I'm at 269,000 miles).

But I've already noticed the temp gauge not getting up to temp, so might as well as eliminate that as an issue.

Best I ever got was 53MPG, though that was 100,000 miles ago.


The thermostat is a pretty easy job. Make sure you get a good one from idparts or kerma. You will lose some coolant so make sure you have some coolant to add after the job is done. Good luck!


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Tdijarhead

Top Post Dawg
Joined
Nov 10, 2013
Location
Lawrenceville PA
TDI
2003 TDI Jetta Daughters Car, 2001 TDI Beetle, Wife’s car, 2005 Golf TDI Mine, all 5 spds
Proper operating temperature is critical to good fuel mileage.
 

Couleetdi

Veteran Member
Joined
Aug 3, 2003
Location
West Wisconsin
TDI
2015 Passat SE TDI
Poor Mileage

For the last year, I've been fighting the poor mileage issue too, 39-42 mpg tank average manually figured, not scangauge. I drive 50/50 town/road driving. Engine temp on scangauge runs around 190, fuel tried lots of stations, filter, you name it, brakes were not dragging, finally in July of this year my A/C quit working.



The coil and clutch went south. Since then no A/C, not had time to fix but my mileage improved on tank average to about 51. Nothing else has happened. Sounds weird, my driving habits sure have not changed.



Not really sure why, as I never used A/C in fall, winter or spring before that other to run it bit to keep lubricated.



couleetdi
 

mrfiat

Veteran Member
Joined
Mar 24, 2008
Location
Los Ranchos, NM
TDI
2003 Jetta TDI (Reflex Silver) , 2003 Jetta TDI Wagon (Black)
I've gotten 31 and 32 mpg from my sedan the last two tanks. I have tried everything on the forums and no luck. I would be very happy with your 39-42 mpg.
 

WildChild80

Veteran Member
Joined
May 30, 2016
Location
Nashville, AR
TDI
2001 Jetta TDI 2000 Jetta TDI 2000 New Beetle TDI ALL 5 speeds
So what's the key, owning a parts house?

Many of us get low 40s with properly maintained cars, so what's the key, worn injectors, cause it ain't maintenance.
From what I can read, roughly a third of us get that magic 50, some even higher.
Sounds like worn nozzles are the culprit. My fun car with 325k miles gets slightly better mileage than the stock Jetta with 302k miles.

I think it's time to send DBW a set of injectors for the stock offering and when those come back it'll be time for the 75k cleaning of the set in the fun car.

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apple4ever

Well-known member
Joined
May 22, 2006
Location
Coatesville, PA
TDI
2002 Jetta TDI, 5sp manual, 280K miles
The thermostat is a pretty easy job. Make sure you get a good one from idparts or kerma. You will lose some coolant so make sure you have some coolant to add after the job is done. Good luck!
That's what I've read!

I used my VagCom and as same as the OP, the sensor rarely gets above 160, even on a 60° day after 20 minutes of driving.
 

apple4ever

Well-known member
Joined
May 22, 2006
Location
Coatesville, PA
TDI
2002 Jetta TDI, 5sp manual, 280K miles
Yep, same as mine, get that replaced!

-Hussman
Good to know!

Wonder if I should replace my coolant temp sensor. I know I said earlier I replaced it, but then I remembered I was going to, but never did for reasons I can't remember.

I'm thinking yes, why not.
 

Hussman

Well-known member
Joined
Aug 8, 2018
Location
Crosslake, Minnesota
TDI
2003 VW Jetta ALH TDI 5 speed
Good to know!



Wonder if I should replace my coolant temp sensor. I know I said earlier I replaced it, but then I remembered I was going to, but never did for reasons I can't remember.



I'm thinking yes, why not.


I would start with the thermostat and see if it improves first, but if you already have the coolant sensor, it’s worth throwing it in.

-Hussman


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DMan1198

Well-known member
Joined
Oct 15, 2017
Location
Slave Lake, AB
TDI
02 VW Jetta
Now, what about the fuel temp sensor? Mine has thrown p0183 as long as I’ve owned it, and it isn’t the sensor in the pump (tested both the stock pump that failed, and the replacement 11mm pump that’s on it now, and they tested the same), but I don’t have the pin out box to test the harness, and I’m not sure what to test on the ecm since the program we use at work just says to use the scanner to tell if the ecm is to be replaced. My car has struggled to get over 40-42 even after a new t-stat, intake cleaning (that did bring it up from 32-36mpg), and some other adjustments. the po had lost the skid plate, and messed the skirts that hold it, and I haven’t gotten around to sorting that, but I don’t drive the thing gingerly by any stretch.
 
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