TDI Timing Revisited

[eb2143]

Thanks for the data Bob. This would indicate that despite what some people claim, relatively small changes in basic timing do effect the "operation" timing in significant ways, right?

 

[jcrews]

I suspect the basic setting sets the datum for timing, so the requested start of injection should change with the basic setting, all else being equal. The ECM learns this value when basic settings mode is activated.

I just haven't bothered to prove that

 

[Bob_Fout]

As I understand it, the ECU can only adjust a certain amount either side of what static timing is set to. If the requested timing is more advanced or retarded than static + dynamic can provide, it's less than optimal.

 

[jcrews]

Having newly rebuilt injectors, I can attest to the specification more or less ensuring that the control device can achieve the requested timing.

Below 1500 RPM, I see at most a degree over, and above that it's where it should be. At idle today requested was 2.2 deg BTDC and actual was 2.4 deg. I've seen it go to 1.8 deg, but 2.4 is the physical floor. Still, in my logs, I don't see any differences at normal running speed.

I can see how when injectors wear and possibly open too early, the green line effectively moves down.

As far as fuel burn is concerned, I can't say, because I've changed too many elements to make a valid decision. I can say that with PP520s and timing where it is (near green), I saw ~56 MPG where 53 was the max before, all else being as equal as humanly possible. Those values were repeated many times. Again, that statement is not valid; I'm only illustrating that my econ is probably not sub-optimal.

 

[Growler]

ok, I have a question about this process..

I checked my car the other day and in basic settings my timing was hovering between the blue & green lines about halfway when warmed up.

I then went to measuring blocks and my specified & actual start were matching like this thread wants them to, but my cold start value was down at like 2.6 or 2.8 (cannot remember exactly)

my question to the masters is this, do I leave this alone or do I want the cold start value to be above 3 somewhere like the picture posted by aNUT?

Thanks!

 

[Bob_Fout]

Hm Aaron, your SOI is 882 RPM. Mine was 904 RPM dead on. Tuning differences?

 

[Growler]

Hm Aaron, your SOI is 882 RPM. Mine was 904 RPM dead on. Tuning differences?

bob, thats not my picture... thats anuts picture, I just reposted it for reference. does my edit help?

my car idles at 903 rpm on the nose.

 

[Bob_Fout]

Oooh, sowwie. Yes the edit helps.

 

[Variant TDI]

The last picture is of most interest. It shows fuel conversion efficiency, which translates to fuel economy if you will at various start of injection timing and EGR rates.

So best fuel economy for this engine under stated operating parameters would be near 30% EGR rate and SOI timing around 4 BDTC.

If this engine had an EGR delete, best fuel conversion efficiency would happen at roughly 2 ATDC, again at 1500 rpm.

So, if I'm reading the graph correctly, leaving the EGR alone (stock) is the path to optimum fuel economy?

 

[tasdrouille]

So, if I'm reading the graph correctly, leaving the EGR alone (stock) is the path to optimum fuel economy?

Ahem...*quiet*...imho increasing EGR and advancing timing accordingly over stock is the path to optimum fuel economy.

I run my EGR around max rate (adaptation value 32300) and my timing at idle around 7 BTDC (adaptation value 33200). I know the timing is out of spec, but I'm careful with it, plus the increased EGR increase the ignition delay so it's really not worse than max advance. There's no harm at the rpms and loads I drive at. At 2000 rpm on a flat highway driving 65 mph I'm at 10 BTDC and max egr valve duty cycle. Actual fuel economy is improved in my case under those conditions.

 

[Growler]

ok, I have a question about this process..
I checked my car the other day and in basic settings my timing was hovering between the blue & green lines about halfway when warmed up.
I then went to measuring blocks and my specified & actual start were matching like this thread wants them to, but my cold start value was down at like 2.6 or 2.8 (cannot remember exactly)
my question to the masters is this, do I leave this alone or do I want the cold start value to be above 3 somewhere like the picture posted by aNUT?
Thanks!

so, do I want my specified & actual to match and be at around .5 atdc and my cold start value to be above 3 at the same time? or do I want my specified & actual to be at 2 atdc and my cold start value to be higher because my egr system is gone?

My EGR fell off and has since been plugged with an EGT probe a long time ago, but it is set to stock value in VCDS (now)

 

[tasdrouille]

so, do I want my specified & actual to match and be at around .5 atdc and my cold start value to be above 3 at the same time? or do I want my specified & actual to be at 2 atdc and my cold start value to be higher because my egr system is gone?

My EGR fell off and has since been plugged with an EGT probe a long time ago, but it is set to stock value in VCDS (now)

Don't worry about the cold start value, it doesn't do anything really.

Since you don't have any EGR anymore, you only have to worry about timing.

Now the question is what do you want? Fuel economy or better response? If you want fuel economy at light loads, like during highway cruising go with 0. If you want better response and better economy at high loads, with an engine that feels it wants to go more, go with 2-3 btdc. This is what I would do if I had no EGR whatsoever.

 

[jcrews]

The actual will almost always be greater than specified at idle unless you retard the timing a lot. Do a log, and you'll see it track tightly, and once over about 1500 RPM, it will do so even at very low load.

You can't judge the timing control system setting based on idle behavior. That only works in basic settings mode.

 

[Growler]

Don't worry about the cold start value, it doesn't do anything really.

Since you don't have any EGR anymore, you only have to worry about timing.

Now the question is what do you want? Fuel economy or better response? If you want fuel economy at light loads, like during highway cruising go with 0. If you want better response and better economy at high loads, with an engine that feels it wants to go more, go with 2-3 btdc. This is what I would do if I had no EGR whatsoever.

well, I got home and played with it and will post what I found and what I did...

Timing Chart Before

Group 4 before

after much fiddlings I got the timing adjusted to here:

I noticed that the specified and actual start were still up near 3.0 or so so I went into Adaptation and was able to bring it down. you can see what it was at and what I wound up setting it to.

and finally, this is where my specified & actual wound up.

If I tried lowering the value in Adaptation any more, they would stop being the same. and I couldn't ever get the specified & actual to go below 1.1 and be the same. Getting it to be 0.5 ATDC was impossible. lowest I saw was 0.8 BTDC and the actual couldn't match it.

My question after all of this is Should I have left it at around 3.0 and 32900 in the adaptation? or did I do a good thing by bringing it down to 1.1?

I believe that Jeff (RC) must have adjusted my group 4 to the 32900 to set my Specified & actual at around 3.0 because I don't believe that Glen (MOGolf) would have done this.

I will drive the car like this until the weekend when I will be seeing Jeff at Whitbreads GTG and see what he has to say. if he wants me to adjust it back to 32900, I will. but until then..

Discuss

 

[MAXRPM]

Best results for me has been leaving the timing between the middle and the upper line and having it at 3 btdc, I have no egr, if I set the timing higher my egt will go higher. I have not done any test about the fuel economy.

 

[tasdrouille]

If I tried lowering the value in Adaptation any more, they would stop being the same. and I couldn't ever get the specified & actual to go below 1.1 and be the same. Getting it to be 0.5 ATDC was impossible. lowest I saw was 0.8 BTDC and the actual couldn't match it.

This is because the basic timing is set in such a way the ECU can't adapt below 1.1. I posted in a previous post about how it works.

My question after all of this is Should I have left it at around 3.0 and 32900 in the adaptation? or did I do a good thing by bringing it down to 1.1?

It won't make a world of a difference. Since you don't have any EGR you'll have good fuel economy at low/mid loads. At 3 BTDC you'd have a tad more happy revving engine and better fuel economy at high loads but that's it. You steeled pretty much for the middle ground.

 

[Growler]

so it sounds like I did the best thing for economy for my car in my normal driving style.. good economy on long steady trips, and decent performance when I wanna have fun.

BTW, it still pulls nicely to redline.

 

[BioBob]

Jumping Values

Interesting thread, in that I was just about to advance my timing up toward the green line.

I just installed new nozzles (Sprint 520's) and while adjusting my IQ, I thought I would check my timing. Surprisingly it had dropped from mid high to center, and I am assuming that was to a different #3 injector. I then thought I would refresh my memory relative to timing and found this thread. Being a Hypermiler (trying to get to 70+), these new thoughts got my attention.

I then checked block 004 and now am more confused than ever. Here is what I found:

Specified Start -- .4 BTDC
Actual Start -- .4 BTDC and jumping to .7 with nothing in
between, and occasionally jumping to .9

Is this normal? I had assumed that the Actual Start value would be stable.

Bad Assumption?

Your thoughts before I put the wrenches away !

Thanks

 

[Bob_Fout]

Mine jumped around some too.

My static timing though doesn't move at all when you're checking it, though.

 

[greengeeker]

biobob, did you have your injectors balanced? where did you put your timing before you checked group 4?

 

[BioBob]

Injector Balance

Hey Nick:

Yes they were indeed balanced, and pop tested.

Frank06 did them for me on his "Instant Gratification" program, and that is why I have a new #3 (as well as 1,2,4,). I send my bodies back to him and they go on to the next guy.

I did no changes to the timing before I went to group 004, in fact I still have made no changes to the timing as I'm lurking around the center point. My fuel temp seems low (42) but I don't think it will affect the timing.

I did change the IQ from 3 to 6 and I had already altered the EGR to "offroad".

I was just puzzled by the Actual Start values jumping around from .4 to .7 to .9 and no other values.

I have just a touch of smoke at WOT in 1st and she is much smoother. She seems happy with her new nozzles.

I guess for now I will make a long road test and leave the timing where it is.

 

[BioBob]

Jumping Values

Hey Bob:

Thanks for the input!

I'm glad to hear that the Actual Start is not a fixed value.

What was the total range that you "jumped"?

Thanks again.

 

[Growler]

mine moves around as well.
the important thing is that the specified & actual values do eventually match or come together. I noticed yesterday that it can sometimes take a little time to get them to settle on a new value if you are making any adaptations to group 4.

if specified & actual do ever actually match, then you should be good to go.

 

[Bob_Fout]

Hey Bob:

Thanks for the input!

I'm glad to hear that the Actual Start is not a fixed value.

What was the total range that you "jumped"?

Thanks again.

Mine went the other way I think. 0.2, 0.4, 0.6. Fluxed between them. I will check it this weekend after a nice long drive.

 

[mannytranny]

I did my TB about 5k ago and have been meaning to check the timing again. Last time I set the timing, I was under the impression that the 'Cage Mod' was the way to go...so I set the timing at a hair above the upper limit. I cannot claim that I noticed any better mileage, but thats a tough one to call because I did some other mods (17 in wheels) around that time.

I got on VC and checked the timing. Apparently the belt stretched or something, because timing had become a bit more advanced. So I popped off the Ip cover and moved the pump back and got the timing just a hair below the center line. Seems to start a bit differently, maybe a teeny bit less power at WOT and high RPM. Maybe not.

Thanks for the reminder!

 

[BioBob]

Relief

Hey Growler:

Thanks for the "thumbs up"!

I'm relieved to know that I didn't have some kind of anomaly.

Now we'll go and see how she does on the quest for a 70 MPG tank.

Thanks Again

 

[greengeeker]

Consider me another data point - I made the switch tonight. Results are exactly as aNut's in post #1...except my timing ended up a litte more retarded than his since I ran out of time to dial it in. I'll have to report back on economy and driveability.

 

[Bob_Fout]

OK, timing changed back to halfway between green and blue lines. I'll be able to watch EGTs today on the highway and get a feel for peppyness too.

 

[greenskeeper]

I just bumped my timing a bit after re-reading this thread.

On my car as I mentioned earlier the actual vs requested timing has always been matched.

However, with a hot engine when going from measuring to basic settings I could hear the engine change tone when the ECU was removed from controlling timing.

I have my timing adapted in vagcom for more advance. So by listening to the engine I have moved the timing above the top line in the graph, but the engine sounds identical when going from measuring to basic settings.

I would think that this would allow the timing control to be regulated better by the ECU since at idle and hot both mechanical and physical timing are set the same.

If I didn't have the adaption of the timing, setting it to the middle line would do the same thing correct?

How can I tell how much the SOI solenoid is working to keep up with timing?

 

[npdimonte]

Ok, I have some question because I just finished my first TB change on my ‘03 Jetta and I'll say up front, I'm no expert, I'm a newbe. When I attempted my first adjustment, the TDIGraph displayed a warning “Engine (ECT) not warm enough!”. But, my Bentley says that as long field 7 is above 73 (85 degC) I’m good to go, which was in the 80’s. I did notice that as my engine warmed up, this value would slowly drop. However, I first replaced the ECT, but no good, still reading around 80-85 degC (group 4 I believe). Next, changed thermo with new 87 degC, this fixed the problem, but curiously, my timing marks didn’t change and the TDIGraph said something like “timing dead on”.

So, test drove to verify MPG was still at 53.3 highway, but was very disappointed to see it drop to 48.7mpg. Why, I had the Specified & Actual start set the same and cold start value in range as seen below.

So, I thought I would advance the timing a little.

But now my “start” values are off......

But, the results are that my MPG increase to 56.7mpg highway. Actually, about 5% was around town driving.


Questions.
1) With my timing slightly advanced and cold start value out of range, what are the negatives? short term? long term?
2) What value does the TDIGraph use for temperature? Field 7 of group 000? From group 004? before changing thermo, clicking on “80 degC=Hot” removed the ECT warning message.
3) Bentley says that as long as my timing is within range, I need not change it. No reference to start values in Bentley associated to timing that I could find (I have a hard time --no pun intended-- finding things in this manual). So, is it necessary to be concerned about the start values?
4) Am I reading the data wrong?

P.S. Both test drives where performed on the same day and same driving distance. The first test was purely highway (48.7mpg) while the second test was only 95% highway (56.7mpg).