ALH Bad Mileage

Hussman

Well-known member
Joined
Aug 8, 2018
Location
Crosslake, Minnesota
TDI
2003 VW Jetta ALH TDI 5 speed
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.


Driving hard will kill your mileage, also, if you can’t get over 42 even with driving like grandma, then go for some new nozzles.


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ahldailydriver02

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May 9, 2019
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Arlington, Ne
TDI
02 Jetta 5 speed, 03 Jetta Wagon 5 speed
Reviving an old thread here. So I have an 03 Jetta TDI Wagon 5 speed that I bought a few years back with 115,000 miles on it, currently with 132,000 miles. I have been working on it slowly, started out with intake cleaning, 2.5 turbo back exhaust, stage 1 Malone tune, new struts, wheel bearings, tires ect. Every possible thing has been replaced or is in good working condition, however this wagon has never been fantastic on mpg. I struggled to get 48mpg with it. I just recently installed Wuzetem .205 injectors set by Franko6 with a Malone stage 2 tune. Timing is set at 70/110, turbo works, actuator works ect. But my mpg sucks, struggled to get 45mpg on a 380 mile trip going 68-70mph. Seems to have the power, minimal to no smoke, and I have fiddled with the IQ setting between 4.8-7.0 power will changed, but mpg is not what I was expecting. My 02 sedan, same set up will get 56mpg. Franko6 has been a great resource and has helped me a lot, but still haven't figured this out yet. Any suggestions? Thanks in advance.
 
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IndigoBlueWagon

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South of Boston
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'97 Passat, '99.5 Golf, '02 Jetta Wagon, '15 GSW
First, are you sure you got the same "fill" both times? 380 miles isn't a lot in these cars, and the difference between 45 and 50 MPG for that many miles is about a gallon of fuel. If the first fill foamed a lot, or if you weren't venting and filling the car until you see clear fuel in the filler neck both times, you probably aren't getting an accurate MPG number.

Failing that, it seems that improving economy takes changing a lot of little things, not one big thing. Is the tune matched to the new nozzles? What IQ does Malone recommend? Are you sure the static (not running) timing is spot on: meaning are you sure the cam, crank and pump are exactly at TDC at the same time? The turbo actuator may be working fine, but are the curves for actual vs. requested boost well matched, not lagging? Is your injection pump meeting the ECU's fuel request?

Then there's the mundane stuff like tire inflation pressures, brake dragging, and, of course, driving style.

My Wagon has a setup that probably makes similar power to yours, and I get 50-52 if I run no faster than 75 on the highway, 48 if I go 80+. I do have a .700 5th, which I think helps. But I agree you should be doing better.
 

csstevej

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north nj
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2001 golf tdi 4 door auto now a manual, mine, 2000 golf 2 door M/T son's,daughters 98 NB non-TDI 2.0, 2003 TDI NB for next daughter, head repaired and on road,gluten for punishment got another tdi 2001NB,another yellow tdi NB
If you have Vcds check your coolant temp sensor…..it’s a single dual sensor , one leg goes to the temp gauge on the dash and the other to the ecu…… the dash one is useless…..however the one going to the ecu is important….if it’s not reading correctly ( usually fails toward the cold side ) the ecu doesn’t think the engine is up to operating temp and will run rich. Also if you have an infrared gun you can shoot the returning coolant to the ball it will be a couple of degrees off but will be close enough .
If that checks out it can be your thermostat …opening too far and not allowing engine to get up to temp.
I’ve seen the dash read 190 degrees while Vcds reads 160 degrees.
I’ve lost 5-6 mpg with a bad thermostat…..if it is that make sure you get an oem one…..you don’t want to do it twice….
 

ahldailydriver02

Veteran Member
Joined
May 9, 2019
Location
Arlington, Ne
TDI
02 Jetta 5 speed, 03 Jetta Wagon 5 speed
Fill ups have been consistent, as I ensure that I don't fill to fast to minimize foam build up, and I keep an eye on my fuel gauge to ensure its represents to how many gallons being pumped. I fill until I see the fuel at the filler neck.

Tune was matched for my exhaust, injectors and VNT15. Malone didn't have a specific IQ setting, their response was, each car will be different. I can not verify that the pump, cam and crank are all at TDC. When the timing belt was done, (by reputable VW mechanic) the cam and crank were at TDC and I assume injection pump was at TDC when timing belt was done as he locked the pump. I have set the pump time via VagCom to 70/110. The one thing that I have noticed is that my IQ does jump around some at idle. Example: IQ set at 6.0 and will bounce from 5.6-6.2 sometimes and other times stay right at 6.0. Don't know if that is an issue or not. Maybe that's the problem? I would assume the pump is meeting the ECU's fuel needs, but how do I check for that?

I have done a few test runs and the actual vs requested boost match pretty darn close and peaks about 2560 on VagCom

New brakes and rotors all the way around, no brake drags, and Tires always inflated at 40-42psi. I Don't rod on it and set my cruise too. I drive the wagon the same way I drive my sedan with the same exact set up. I failed to mention that my last trip with the 45mpg was with a tail wind for half of the trip too. I have had my 02 sedan since new so I have pretty good idea on what to look for, but I am stumped on this wagon, obviously I am missing something here that is affecting my mpg.
 

ahldailydriver02

Veteran Member
Joined
May 9, 2019
Location
Arlington, Ne
TDI
02 Jetta 5 speed, 03 Jetta Wagon 5 speed
If you have Vcds check your coolant temp sensor…..it’s a single dual sensor , one leg goes to the temp gauge on the dash and the other to the ecu…… the dash one is useless…..however the one going to the ecu is important….if it’s not reading correctly ( usually fails toward the cold side ) the ecu doesn’t think the engine is up to operating temp and will run rich. Also if you have an infrared gun you can shoot the returning coolant to the ball it will be a couple of degrees off but will be close enough .
If that checks out it can be your thermostat …opening too far and not allowing engine to get up to temp.
I’ve seen the dash read 190 degrees while Vcds reads 160 degrees.
I’ve lost 5-6 mpg with a bad thermostat…..if it is that make sure you get an oem one…..you don’t want to do it twice….
I will check coolant temp with gun and compare with VCDS too, that is one thing I haven't checked on VCDS, I have only relied on the gauge.
 

IndigoBlueWagon

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South of Boston
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'97 Passat, '99.5 Golf, '02 Jetta Wagon, '15 GSW
Thermostat is a good thing to check. It can have a big impact. Check the timing graph in VCDS: If it jumps around it's an indication that the pump is getting worn. Enough for that much of a FE hit? I doubt it, but it doesn't help.

Regarding static timing, if you hook up VCDS and look at toggle between basic settings and measuring blocks and it stays the same, then everything is at TDC. If it moves appreciably, then it isn't.

Malone's should at least have a recommended starting pont for IQ. If the car is set up for the mechanical fueling, I'd set it at 3.0. If it doesn't smoke much at WOT at that setting, leave it. If it does, adjust. Setting the IQ too high won't improve FE.
 

ahldailydriver02

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May 9, 2019
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02 Jetta 5 speed, 03 Jetta Wagon 5 speed
Thermostat is a good thing to check. It can have a big impact. Check the timing graph in VCDS: If it jumps around it's an indication that the pump is getting worn. Enough for that much of a FE hit? I doubt it, but it doesn't help.

Regarding static timing, if you hook up VCDS and look at toggle between basic settings and measuring blocks and it stays the same, then everything is at TDC. If it moves appreciably, then it isn't.

Malone's should at least have a recommended starting pont for IQ. If the car is set up for the mechanical fueling, I'd set it at 3.0. If it doesn't smoke much at WOT at that setting, leave it. If it does, adjust. Setting the IQ too high won't improve FE.
Just checked coolant temp and its 89-91c so we are good there.

Timing in VCDS on basic settings will jump around very little, 70-73 sometimes, if you are talking about the timing graph vs block number 2 in basic settings. Should I lower the timing to more towards the middle of the graph? I always thought it should be closer to the upper part of the graph, close to 70. Maybe I am wrong?

Unfortunately Malone didn't recommend any setting, and they didn't on my sedan either. Franko6 did say that he likes the idle L/Hr to be lower like .5L/Hr. Right not it is at .7L/Hr. Unfortunately I wrecked my sedan in November and haven't had time to fix it otherwise I would check VCDS side by side to see if I could find any differences. Bur from what I do remember my sedans idle L/Hr was .8L/Hr and netted me amazing mpg.

I can lower the IQ. For my trip the IQ was set at 4.6. I thought maybe I should raise it. My sedans IQ was set at 6.8 with same setup. Weird for sure. I was worried about lowering the IQ down past 4.6 only because of how my sedan was set. I can try it though.
 

IndigoBlueWagon

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'97 Passat, '99.5 Golf, '02 Jetta Wagon, '15 GSW
Stock IQ varies, but 2.2-2.8 is pretty normal for an unmodified car. I've always felt that if you have to move the IQ much above 4 to reduce smoke then there's a mismatch between the hardware in the car and the tune.

I'd leave the timing where it is.
 

ahldailydriver02

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TDI
02 Jetta 5 speed, 03 Jetta Wagon 5 speed
Stock IQ varies, but 2.2-2.8 is pretty normal for an unmodified car. I've always felt that if you have to move the IQ much above 4 to reduce smoke then there's a mismatch between the hardware in the car and the tune.

I'd leave the timing where it is.
Do you believe that each car is set up a little different from factory too? Like each car is supposed to be the same but maybe the ECU has some differences that will change how the car responds with modifications?

Are you saying to leave the pump timing at 70 like I have it and just reduce the IQ to a tolerable smoke level? I am fine with that and will do a test trip to see if that changes the mpg.
 

IndigoBlueWagon

TDIClub Enthusiast, Principal IDParts, Vendor , w/
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Do you believe that each car is set up a little different from factory too? Like each car is supposed to be the same but maybe the ECU has some differences that will change how the car responds with modifications?

Are you saying to leave the pump timing at 70 like I have it and just reduce the IQ to a tolerable smoke level? I am fine with that and will do a test trip to see if that changes the mpg.
Don't know how the cars are set up, as I never checked IQ on one that was new enough for it not to have been altered. But that range seems typical.

Yes, lower the IQ and leave the timing alone. See what happens. But as I posted above, that alone probably isn't going to make a big difference.
 

ahldailydriver02

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Arlington, Ne
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02 Jetta 5 speed, 03 Jetta Wagon 5 speed
I thought lowering the iq was more fuel, and raising it was less? Was just reading about the hammer mod....
Found this helpful. Sorry if we're not allowed to link to other forums.
You are correct on how the IQ reacts to when raising vs lowering when it comes to fuel distribution. I am not sure if members care that you posted a link from another forum, I am sure if its an issue someone will speak up.
 

ahldailydriver02

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Location
Arlington, Ne
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02 Jetta 5 speed, 03 Jetta Wagon 5 speed
Don't know how the cars are set up, as I never checked IQ on one that was new enough for it not to have been altered. But that range seems typical.

Yes, lower the IQ and leave the timing alone. See what happens. But as I posted above, that alone probably isn't going to make a big difference.
Ok, I will lower the IQ down some to a reasonable smoke level, leave the timing alone for now and see if I can take it for another trip to see how it responds. Thank you,

If anyone else wants to chime in, please do I am welcome to any advice or criticism. I just want to figure out the reason for this issue.
 

super1

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Location
NY
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none
Not sure if your doing this but this fuel ventectomy it
allows you to put a few more gallons in your tank, so maybe your fill ups are inconsistent?
 

ahldailydriver02

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02 Jetta 5 speed, 03 Jetta Wagon 5 speed
Not sure if your doing this but this fuel ventectomy it
allows you to put a few more gallons in your tank, so maybe your fill ups are inconsistent?
I haven't taken the vent out, however I usually put on the vent with the nozzle tip until its filled to the neck, this would simulate having the vent out. I appreciate the idea. Thank you
 

ahldailydriver02

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Don't know how the cars are set up, as I never checked IQ on one that was new enough for it not to have been altered. But that range seems typical.

Yes, lower the IQ and leave the timing alone. See what happens. But as I posted above, that alone probably isn't going to make a big difference.
I did realize there is one difference between my wagon and sedan, my sedan has turbo back factory size piping. Do you think that the 2.5" turbo back exhaust written into the tune makes any difference with the IQ and smoke level vs mpg? I am only asking because the wagon smokes very little compared to my sedan. Maybe that is the difference? I grasping at straws here obviously.
 

IndigoBlueWagon

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Larger exhaust will help reduce smoke, because it allows the turbo to spool faster.
 

ahldailydriver02

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02 Jetta 5 speed, 03 Jetta Wagon 5 speed
Larger exhaust will help reduce smoke, because it allows the turbo to spool faster.
That explains why my smoke level on the wagon is much, much less than my sedan. I set the IQ to 3.8, runs very well, can't really see any smoke from my mirror. Most times I have someone follow me to gauge smoke level. But I can't imagine that the exhaust would have anything to do with fuel mileage.
 

ahldailydriver02

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I have an update, sorry it took so long but the winds here have been crazy. I have the IQ set at 3.8 and could only take it for a 200 mile run, but ended up getting 50mpg, a lot better than I was getting with it, but it was also a perfect day for temperature and wind. I am happier with this number but I will continue to play with it for a while and report back again. Next up is my sons wagon, that has had the same issue as mine, so we shall see what his does once I have it put back together too. Thanks for everyone's help and please feel free to throw out any advice.
 

ahldailydriver02

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Just wanted to provide an update. Another member told me to drop the IQ to 3.0, so I did and took it for a 300 mile trip. Car ran great, however when I got back the IQ didn't stay at 3.0 it was actually sitting at 3.6-3.8 and my FE was 45mpg. The IQ has changed on me before and sometimes by more than 1 whole number. I Not sure why that is happening as the car only has 130,000 miles on it. Also still can't figure out why I am struggling to get 50+ mpg with this car. I have replaced all air lines, checked actuator, replaced wheel bearings & brakes. I can't decided if I want to raise the IQ up to a higher number like I had to in my sedan or leave here and be satisfied with 45mpg. I know that sounds dumb, but I have had 4 of these cars and this is the only one that has not been able to get 50+ mpg. Any other suggestions would be great.
 

J_dude

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SK Canada
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2003 1.9l “Jedi”
Just wanted to provide an update. Another member told me to drop the IQ to 3.0, so I did and took it for a 300 mile trip. Car ran great, however when I got back the IQ didn't stay at 3.0 it was actually sitting at 3.6-3.8 and my FE was 45mpg. The IQ has changed on me before and sometimes by more than 1 whole number. I Not sure why that is happening as the car only has 130,000 miles on it. Also still can't figure out why I am struggling to get 50+ mpg with this car. I have replaced all air lines, checked actuator, replaced wheel bearings & brakes. I can't decided if I want to raise the IQ up to a higher number like I had to in my sedan or leave here and be satisfied with 45mpg. I know that sounds dumb, but I have had 4 of these cars and this is the only one that has not been able to get 50+ mpg. Any other suggestions would be great.
I didn’t go back and read the whole thread but, have you read Oilhammer’s fuel economy thread yet?


Also, I’m not entirely sure, but I think IQ does kinda fluctuate like that a bit.
 

JETaah

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mi 48836
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96 B4V, 1999.5 jettaIV,2005 BEW Beetle
Just wanted to provide an update. Another member told me to drop the IQ to 3.0, so I did and took it for a 300 mile trip. Car ran great, however when I got back the IQ didn't stay at 3.0 it was actually sitting at 3.6-3.8 and my FE was 45mpg. The IQ has changed on me before and sometimes by more than 1 whole number. I Not sure why that is happening as the car only has 130,000 miles on it. Also still can't figure out why I am struggling to get 50+ mpg with this car. I have replaced all air lines, checked actuator, replaced wheel bearings & brakes. I can't decided if I want to raise the IQ up to a higher number like I had to in my sedan or leave here and be satisfied with 45mpg. I know that sounds dumb, but I have had 4 of these cars and this is the only one that has not been able to get 50+ mpg. Any other suggestions would be great.
IQ number will go up with the addition of load such as AC, headlights, glow plugs, cooling fans, etc...
 
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BobnOH

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May 29, 2004
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central Ohio
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New Beetle 2003 manual
FYI only.
The spec for IQ is 2.2 to 9. The ECU will handle anything it that range.
I bought a 99.5 new, IQ was around 2.0. Drove hard average 45 mpg, only got 50 on freeway trips (at 80).
I've read and understand all the threads/posts on IQ, folks report best value is around 4. Believe this may be the most overdiagnosed thing on these cars.
 

Nevada_TDI

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Reno, sort of...
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2001 Jetta TDI
In 18 plus years I have never heard of a tuner not telling their customer where the IQ should be set.
I disagree with that as well as the above poster does as well. The particular tuner in question is not my favourite ( the spelling of favourite should be a giveaway.)
IQ, and timing are two important things to check when initial logs are run, and especially after the tune is installed to verify proper operation.
 

ahldailydriver02

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02 Jetta 5 speed, 03 Jetta Wagon 5 speed
I didn’t go back and read the whole thread but, have you read Oilhammer’s fuel economy thread yet?


Also, I’m not entirely sure, but I think IQ does kinda fluctuate like that a bit.
I have not read his post on this, but I will today, thank you.
 

ahldailydriver02

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In 18 plus years I have never heard of a tuner not telling their customer where the IQ should be set.
I disagree with that as well as the above poster does as well. The particular tuner in question is not my favourite ( the spelling of favourite should be a giveaway.)
IQ, and timing are two important things to check when initial logs are run, and especially after the tune is installed to verify proper operation.
Yeah it surprises me too that they didn't say what the IQ range should be set at. I have been messing with this for a month now and still not happy. I didn't log any runs prior to the tune when I installed the injectors, but I should have. I did set the injectors to low to no smoke at first then tried Franko6 idea of adjusting IQ to where you loose performance and then set it back the the previous IQ. Car runs good, but the economy is not where I think it should be, especially compared to my 2002 sedan. I wrecked the sedan last November and haven't had time to put it back together yet so I can't compare any numbers with it. I am questioning if I should have my tune uploaded again to see if that makes a difference or if it is truly something in my IQ or car itself. I thought about going to a different tuner, but I don't think they can overwrite a tune from another vendor or at least that is what one of them told me. I am just frustrated with the FE is all, because I know it should be better, I want my cake and be able to eat it too.
 
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ahldailydriver02

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I didn’t go back and read the whole thread but, have you read Oilhammer’s fuel economy thread yet?


Also, I’m not entirely sure, but I think IQ does kinda fluctuate like that a bit.
Ok I was wrong I have read Oilhammer's FE thread before and I have checked all those things off the list already, even prior to the tune and injectors. But I appreciate the advice.
 
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