TDI Timing Revisited

[greenskeeper]

Specified start 0.4 BTDC
Actual start 3.5 BTDC
Cold start valve 2.8%

Your timing is too advanced. The valve is at 2.8% so it can't retard the timing any more than 3.5 BTDC, so you need to adjust the pump to get the timing to 0.4 BTDC while keeping the CSV at 2.8%, a small window of adjustment.

 

[B100]

Fuel quality can affect IGNITION DELAY which means the fuel physically takes more/less time to actually ignite and cause a pressure pulse against the piston after it's actually injected. Little known or considered fact: fuel does NOT ignite at the exact time it's injected, but some time after. Anything that affects this ignition delay has a profound impact on every aspect of how the car runs, fuel economy, noise, power, smoke, you name it.

Is it fair to replace "fuel quality" with "cetane number?" If one is using straight D2 in the U.S., they have cetane at approx 42-45. What if the driver has added a cetane booster, or is running a blend of biodiesel? Higher cetane number should equate with a shorter ignition delay...

I'm wondering how one should best use VCDS to adapt to higher cetane, thanks for any insights.

 

[KERMA]

Is it fair to replace "fuel quality" with "cetane number?"

cetane is only one factor of many that influence "fuel quality" and ignition delay and it's not the sole determinant

The factory has already figured out a range that will give acceptable running under a wide range of conditions. Follow Anut's advice and you will be fine.

 

[colinstone]

Your timing is too advanced. The valve is at 2.8% so it can't retard the timing any more than 3.5 BTDC, so you need to adjust the pump to get the timing to 0.4 BTDC while keeping the CSV at 2.8%, a small window of adjustment.

Thanks - and of course some more Qs?
Is the advance too outrageous and can I live with it. What are the effects of continuing?
If the socket handle is "straight up", then a nudge on the pump shaft bolt towards the windscreen will retard?
How much movement do you reckon?

And how do I tell if I have stretch pump bolts - is it possible to tell looking at the bolt heads?

 

[RacerTodd]

If the socket handle is "straight up", then a nudge on the pump shaft bolt towards the windscreen will retard?
How much movement do you reckon?

Yes, towards the windshield retards (pump hub moves CCW), towards the front bumper advances (pump hub moves CW).

If the top of your socket handle moves like 1/16" that's enough to move the timing value halfway across the screen.

Since the amount of movement needed is small, I don't just grab the wrench with my hand and pull. That uses the big arm muscles which aren't good at fine motor movements. Rather, I set my elbows on the core support then grab the top of the wrench with both hands (you'll look like you're praying). I then use just the hand muscles to apply a gentle pressure on the wrench. This also puts the wrench right in front of your eyes so you can see how much it moved.

And how do I tell if I have stretch pump bolts - is it possible to tell looking at the bolt heads?

I don't think you can tell by the bolt heads. The TTY, one-time use bolts have threads that stop halfway up. The reusable bolts are threaded all the way to the head.

 

[colinstone]

I don't think you can tell by the bolt heads. The TTY, one-time use bolts have threads that stop halfway up. The reusable bolts are threaded all the way to the head.

Can I use reusable bolts if the originals were stretch bolts?

Thanks.

 

[ymz]

Can I use reusable bolts if the originals were stretch bolts?

Yes... assuming your ASV engine is almost identical with the ALH engine, the new-style bolts (reusable) are p/n N 903 285 04.

On the ALH, the old-style single-use bolts were black/blue, the newer ones silver/gold - occasionally with a light blue/green anti-corrosion coating.

Yuri

 

[Jesse_Boyer]

If the top of your socket handle moves like 1/16" that's enough to move the timing value halfway across the screen.

Since the amount of movement needed is small, I don't just grab the wrench with my hand and pull. That uses the big arm muscles which aren't good at fine motor movements. Rather, I set my elbows on the core support then grab the top of the wrench with both hands (you'll look like you're praying). I then use just the hand muscles to apply a gentle pressure on the wrench. This also puts the wrench right in front of your eyes so you can see how much it moved.

I've found it's best to mark the bolt/sprocket postion with a sharpie and make an adjustment. You can easily tell how far you've move it that way. After you're done, if you're really anal, you can leave two bolts tight, remove the marked bolt, and clean with carb or brake cleaner on a wrag.

 

[colinstone]

Bolts and 22mm socket ordered.
My socket handle is 199mm socket centre to end. I need to retard by 3.3 degrees, which is just under 6mm movement of end of handle and as handle is 12mm thick, 1/2 a handle width.
(199*22/7/360*3.3=5.73mm)

 

[whitedog]

Bolts and 22mm socket ordered.
My socket handle is 199mm socket centre to end. I need to retard by 3.3 degrees, which is just under 6mm movement of end of handle and as handle is 12mm thick, 1/2 a handle width.
(199*22/7/360*3.3=5.73mm)

Now THATS TDI geek! LOL

 

[FlyTDI Guy]

I guess a skosh, smidgen and similar have no place for the technically bound.

 

[RacerTodd]

Bolts and 22mm socket ordered.
My socket handle is 199mm socket centre to end. I need to retard by 3.3 degrees, which is just under 6mm movement of end of handle and as handle is 12mm thick, 1/2 a handle width.
(199*22/7/360*3.3=5.73mm)

Doesn't VCDS show start of injection in terms of crankshaft degrees?

If so, the pump needs to move 1/2 that amount or about 2.85mm movement of the handle. This due to the fact that the pump, like the cam, turns at 1/2 crank speed.

 

[colinstone]

Doesn't VCDS show start of injection in terms of crankshaft degrees?

If so, the pump needs to move 1/2 that amount or about 2.85mm movement of the handle. This due to the fact that the pump, like the cam, turns at 1/2 crank speed.

Yes, of course. Thanks for pointing out that basic error. A teeny amount then.

 

[colinstone]

Another Q. Monitoring requested and actual injection, the engine is noisier when the gap between requested and actual is largest.
Is this the equivalent of pre ignition/pre detonation?

 

[greenskeeper]

actual is what is physically happening, the gap shouldn't mean anything unless actual is really far advanced compared to requested. What are the numbers you are seeing for requested vs actual?

 

[Bdwilliams01]

Thanks for Vag Com help

Thanks for the help. just got my Ross Tech Vag Com, and my 2002 TDI beetle timing needs some adjusting I think. I did find it at 4.0 tdc, but I will use your tutorial and see if I cant get it set for better fuel mileage

 

[Bdwilliams01]

Timing adjustment after belt change for best mpg ?

So I am going to try the below adjustments to see if I can get my ALH TDI motor in my 2002 beetle to do better than it is. The timing belt was changed by previous owner, and he was not aware of the "tweeking" that can be done if you have a Vag-Com. Since I now own 3 TDI's (02 beetle, 11 Jetta, 13 Passat) I figured the Vag-Com was the right choice. I am hoping to get my beetle over 40 mpg, right now its in mid 30's. Transmission is re-manufactured, so I am figuring its timing check first. Any input is greatly appreciated

 

[greenskeeper]

I run 5 degrees advanced in adaption and then set the pump so the duty cycle is 2.9%. I ignore the timing graph.

Specified vs Actual are both 5.5 degrees

With this setup I have run well over 100k miles with no problems and a solid 4-5mpg increase over stock timing.

 

[B100]

I run 5 degrees advanced in adaptation and then set the pump so the duty cycle is 2.9%. I ignore the timing graph.

Specified vs Actual are both 5.5 degrees

With this setup I have run well over 100k miles with no problems and a solid 4-5mpg increase over stock timing.

Short, sweet, and simple.

 

[AV8RLEO]

So much like the OP noted my timing graph had only the vertical yellow line to start with (didn't think to screen grab that one sorry), so I bumped the timing more advanced to "bring the graph around."

This is the initial graph and Group 004 readout.



Couldn't get the graph and data blocks to play nice and show up at the same time so I took two separate screen shots.

Here is the graph showing the vertical and horizontal lines very near the blue diagonal.



Here is a screen shot of the Group 004 data blocks, again after the 2nd tweak. You will notice that I managed to get the specified and actual injection nuts on, but my Cold Start Injector Duty Cycle is 39%.



Not sure if the OP is following this thread anymore but how does this look? What do people think? Total time on this was maybe an hour tops.

That being said the temperature did fall off as I was diddling with the car off and on, so tomorrow I'm going to drive it for about 40 minutes and throw it on the VCDS again...

Later!

 

[AV8RLEO]

So I drove my car home about 20-25 miles today and immediately re-hooked the VCDS to double check the timing.

Here's the graph:


And here's the screen shot of the Group 004 data blocks:

 

[aNUT]

AV8RLEO -

That should be about perfect. The advance solenoid uses case pressure to move the timing control ring in the pump. Case pressure increases with engine speed. Don't sweat an idle advance solenoid DC of up to 50%. Requested timing at idle is going to depend on a number of factors; namely fuel temp and coolant temp.

The whole point of this thread was to get folks to think about what they're actually doing when setting the pump timing, with the goal being that you want to let the ECU have full control under all circumstances. Basically I just got tired of people blindly propagating the 'set it on the green' mantra.

 

[Area351]

Forgive my ignorance but did they change something drastically in the newer versions of VCDS?

I'm running version 12.xx and my graphs look nothing like what is shown. I get 3 horizontal lines that are yellow, green (nearly overlapping the yellow) and red. There are no diagonal lines or vertical lines that intersect pin pointing the timing..... There is also no button for "TDI timing" or the drop down to select what engine you are checking.

I was able to set it using basic servings to roughly 2 BTDC and 2-3% duty cycle, but cannot make heads or tails of the graph. After doing the timing belt, it was having a really hard time starting and this seems to have helped a lot.

I took some screen shots but can't upload them from my phone right now.

Any ideas on what's changed? Ross Tech's site is outdated and still only lists a plugin that is available for download along with screen shots of it.

 

[Area351]

Here are some screen shots of what I'm seeing, and I just realized it's VC Scope.

I just checked my install, and the plug in is there in the same directory along with VCDS, but I never see the button you guys are referring to to start the appication.

 

[Area351]

My bad. I was in group 004 and not 000.

I just found it.

 

[AV8RLEO]

I'm sorry... did you say something about timing? I was too distracted by the background on your computer!!!

 

[Dimitri16V]

that "timing" looks perfect !!

 

[Wankel7]

So waiting for Block 9 to get to at least 110 and then setting block two to at least 70 isn't the best way to go?

I will follow this write up and see how it turns out

 

[Mxmaverick49]

so i just checked my jetta and my graph was only slightly diff than your optimal timing graph. my fuel temp was closer to 90. but the program stated timing was dead on. it did deviate a couple times to "slighly retarded" how much of a problem will this give me?

 

[elicon200]

Okay, I read this entire thread and learn a lot. I made the adjustments and noticed a performance change, etc etc.

I plan on chipping soon, will I have to make the changes again? Or are they eliminated depending on the new programming?