Working on my fuel economy issues.. Plz help..

AnotherPerson

Veteran Member
Joined
Oct 24, 2015
Location
New Orleans
TDI
1999 Beetle
I'm running newly installed 764's, other than that it's stock...timing was midway between the middle and top bands. I hammer modded the pump to get an IQ of 5.5....

With the stock nozzles, IQ of 3.2 and timing where it was above, I averaged 48.4 mpg for 5 tanks.

After changing the nozzles, no other changes, the mileage dropped to 39.3. I saw another post here regarding demanded vs. actual...for increased mileage...so today I changed it to the highest mechanical I could get it and still meet demanded....we'll see how it goes.

On the sheet from Kerma, they recommended running the timing at the top of the band for the 764's...if I don't see an increase in mileage in this tank with this timing change, I'm going to the top of the band....


Your tuned. I'm not. I know my egr isn't helping any now tho as the times when the egr should be open, the car blows more fuel smoke.
 

USMCShooter

Active member
Joined
Mar 17, 2016
Location
Pensacola, FL
TDI
'98 Jetta ALH, 99.5 Jetta ALH
No, I'm not tuned yet....I've got to clutch and turbo it before I tune it...so it's bone stock except for the 764's at this point.
 

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
ALH timing
I have a little to add to aNUT's method of obtaining a good match between the pump's static and dynamic timing settings.
Rather than use measuring block 004 to match things up, I use measuring block 000, field 2. That is the raw timing data in much more fine increments than found in measuring block 004.
Typically, once the engine is fully warmed up, thermostat opened (around 87-95C preferably) that is when you check the timing.
Goto measuring block zero, make note of what the number in field 2 is. With it fully warmed up, it should be in the 55-62 range at idle. If it's higher than that, you likely have the pump statically set higher than what the computer is requesting.
Hit basic settings, note the change in field 2. If no change happens, the pump is in fact statically set more advanced than what the computer is requesting.
If the number dronps, the static setting is lower than what it's requesting. My experience has been that when the car is properly warmed up, the static setting vs. requested is practically right on the middle line, or around a value of 55 in field 2, measuring block 000.
So that's what I've been doing lately, I make the mechanical adjustment with the engine fully warm until I get the most minimal drop in measuring block 000 field 2 value when I switch to basic settings.
When you're done, you can double check your work in measuring block 4 if you like, but when done right, those two numbers (actual vs. requested) will absolutely match and the pump won't have to work very hard to get it there.
I have done this for a few customers very recently. I will have to try it on my Mk3 soon. Fuel economy has been less than optimal lately! Though, it may have something to do with my driving style... and the fact I frequently haul very heavy tools around (pretty much on the bump stops in the rear)!
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Sometimes it's good to have a refresher. I frequently get questions about optimizing mileage, or see threads about reduction in mileage after a timing belt change. This post addresses timing subtleties on VE cars, '96-'03 in North America.
Firstly, here's a screen by screen, step by step, pictorial on checking static timing with VCDS:
Connect the Vagcom to the OBD2 port located
a) above your left shin if you have an A4
b) behind the windshield wiper switch if you have a B4
c) next to the ash tray if you have an A3
Open VCDS.
Click "select"
Click "engine"
Wait for VCDS to establish a connection with the ECU.
Once in a blue moon, VCDS won't do this with the car running. If this is the case, turn the car off, then the ignition to on, (but not start) make the engine controller connection, start the car, and continue.
Click "measuring blocks"
Select group 000. Click "go". Click "switch to basic settings".
Click "TDI Timing"
The following graph will appear.
From the drop down menu in the lower right corner, select your engine.
The apex of the horizontal and vertical yellow lines is where the timing is set. If there are no yellow lines, the timing is very retarded. If there is only a vertical yellow line, the timing is very advanced. Sometimes on A3s and B4s VCDS gets confused when the timing is very retarded, and plots it as very advanced. Advance the timing, and the graph will 'come around.'
Adjusting the timing will not be covered in this how to. Please refer to the timing belt procedure for your car regarding how to do so. A3/B4 A4
Note that timing should be checked with the vehicle at operating temperature. The timing graph is graded by fuel temp, but advance rises slightly (~.5*) after the motor warms up.
OK, so that's the basic stuff out of the way. Before you're bored and move onto the next thread on oil banter, here's where the subtleties come in. Technically, with the apex between the red and green diagonal lines, timing is within spec. TDIclub dogma dictates that the driver wants the timing as close to the green as possible. The following photo is often referenced. The reason people claim this is optimal is to reduce EGTs. This is not true. More on that later.
Let's have a look at measuring blocks -> group 004. This shows actual and specified start of ignition.
Note that the actual start of injection cannot match specified with advanced timing. The Advance Solenoid/Cold Start Valve/N108 duty cycle is pegged at 2.8%. That means the minimum amount of advance is 2.6*. So what you say? Here's the rub. At light load, say 70mph on level ground, where one will get the best milage, specified advance will be .5*-1.5*BTDC. If the ECU cannot achieve requested (optimal) advance, economy suffers to the tune of ~5%. For us TDI nerds, 2-4 mpg matters.
So here's how I time cars:
I put the timing in the graph, then I look at group 004. I set the timing as advanced as I can get it, but retarded enough that actual can meet specified start of injection at idle.
And here's the graph with optimal timing:
Notice that I'm not even above the blue! On a cold day with not so stellar fuel in the tank, that apex can be a dotted white line or so above the red. This is very counter to the theory that's been propogated on these forums...but the car is more efficient.
Now, about that whole EGT thing. Shorter injection duration and earlier start of injection does reduce EGTs, but setting the static timing advanced doesn't achieve this. Higher injection pressures coupled with tuning that's optimized for the fueling hardware on the car does, but not advancing the timing.
Below is a log taken from my car at WOT and stratospheric (for a diesel) engine speed. These are the conditions that require maximum advance I've cropped off the speed, but this section of the log was taken between 3600 and 4600 RPM. It's clear that the car is only requesting a bit more the 13* advance, and the car can easily achieve over 15*. The Duty cycle (also not shown) is between 70-85%, so more can be had if necessary. Essentially, setting the timing for optimal economy does not sacrifice advance during high load situations as once thought.
The above graph was generated using JollyGreenGiant's superb plotting software.


I found the above on this site. I think it was in the DIY thread. The original has vcds pictures to make it easier.
My daughter just got a Beetle, she's getting around 40-41 mpg. So I'm fine tuning it. I've always been a proponent of IQ around 5 and the timing at the top line. That's where I set hers and 40ish is the result. I'm trying for over 50. So I reset her timing to around 48 where the start of injection and specified just about match.

She hasn't driven it much yet I just changed it two nights ago, I'm hoping it's the magic mpg bullet. I'll see if I can link to the original post.


http://forums.tdiclub.com/showthread.php?t=240450&highlight=aNut+timing

Worth a read if you haven't already.
 
Last edited:

marinetech

Member
Joined
Apr 23, 2017
Location
finland
TDI
audi
Have you checked the mechanical timing, with lock down tools not just with VCDS?
How's the air filter?
Does your car have a snow screen?
If yes has it been cleaned ?

second that, i thought mechanical timing could be a possible cause. check the belt is tight on the tension side. if the thermostat is stuck open the fuel consumption should be a bit more than that so you can write it off pretty much
 

AnotherPerson

Veteran Member
Joined
Oct 24, 2015
Location
New Orleans
TDI
1999 Beetle
Thermostat is good. I'm in the process of getting info together and tomorrow I'm gonna check my ecu for sockets. Previous owner said he got the car tuned for fuel economy. Once I find that out I'm gonna get the tune to get everything straight there. Should be plugging in vcds tomorrow and that's when I'm gonna verify the injectors and all. Been working a ton the past couple weeks.


The car still randomly will smoke when taking off normal acceleration and I'm hoping that's just something related to the egr not being turned off.
 

AnotherPerson

Veteran Member
Joined
Oct 24, 2015
Location
New Orleans
TDI
1999 Beetle
Don't have time to do any logs but I had to get the ecu pn so I pulled a couple of things. Does the injector deviation look off? Injectors are barely a month old from dbw.


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AnotherPerson

Veteran Member
Joined
Oct 24, 2015
Location
New Orleans
TDI
1999 Beetle
Prior to the new injectors the old ones were very close together. Can't find the post where I put the info.


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UhOh

Top Post Dawg
Joined
Dec 24, 2014
Location
PNW
TDI
2000 & 2003 Golf GLS (2005 Mercedes E320 CDI)
Replacing "injector" with "cylinder" would be the more appropriate way to look at what these numbers mean.

The deviation just means what the injectors are being asked to do to help compensate.

You're within spec, though I don't like seeing such a range as this (total delta of 2.4). I don't think that this is your smoking gun.

Timing is a bit advanced.
 

AnotherPerson

Veteran Member
Joined
Oct 24, 2015
Location
New Orleans
TDI
1999 Beetle
Replacing "injector" with "cylinder" would be the more appropriate way to look at what these numbers mean.

The deviation just means what the injectors are being asked to do to help compensate.

You're within spec, though I don't like seeing such a range as this (total delta of 2.4). I don't think that this is your smoking gun.

Timing is a bit advanced.


I have the SOI slightly under the green advanced line. So that one looks ok as well than.

I got a ecu part number now going to Malone as I do sometimes have the car feel flat. But I believe that's to do with tuning. Turbo actual and specified was slightly apart but it was less than 100 apart. That could be based on the fact I got a vnt17 couldn't it?


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