My TDI tuning adventure

2004LB7

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Going to try and document my TDI tuning here

Story starts with my first TDI. A 2009 Jetta. Using the CBEA engine that is common rail with the CP4.1 high pressure fuel pump. I started with a generic Malone stage 2 tune. Took the car from a stock 140HP to a claimed 184HP. Probably only added 20-30 actual HP. Car drove fine. Would bark the tires but not really a great boost as I'd hopped. Three posable reasons. Emissions system still intact, limited turbo size, and later finding out that while Malone tuning being popular, is not really all that great.

Addressed the DPF and catalyst issue by lighting them up. Retune to address the codes, etc. no change in performance or MPG. Disappointed. But car drove good so didn't complain.

Fast forward a year or two. VW has a shit show on their hands with the so called emissions scandal. VW was forced to make modifications to the effected cars to include a DEF system along with a new exhaust and programming to the ECU. Not wanting to nuter my car I elected to ignore the "update". I received a letter from DMV stating that my registration will not be renewed until I get the "fix" from VW. Backed into a corner, I decided to go with the buy-back which was slightly more then I paid for the vehicle to begin with.

Took the money and found a 2006 TDI that was not on the recall list. But quicky found out that the 90HP of that year was no fun. Being that this car was 1/3 what I got paid out for the 2009, I took some of the funds and bought a larger turbo and injectors. I also did ARP head studs and a colt stage 2 cam

Hardware list:
ARP Head Studs
Colt Stage 2 Cam
turbo: gtb1749v
1043 injectors which should be close to the same injectors used in Europe that make 170HP on their TDI's. Depending on tuning could potentially reach 200HP

Once again, back with Malone for tuning. Opted for a custom stage 5 tune to be able to accommodate the new hardware. I think it was about 6 to 8 revisions later, I had a drivable car. First tunes smoked a lot with moderate power increase. Maybe got into the 140HP range. Probably a little more. But the smoke was not acceptable. Finally settled on a pretty clean tune but was probably only 120HP. Was drivable but lacking power down low with turbo surge coming on later with a good boost in power. Was ok but turbo lag sucked. Gave up on Malone and just kept what I got.

A few years later I keep seeing a another turner pop up in the TDI club forum threads. Active member who regularly posts helpful tuning information. Plus many recommending him. Thinking maybe he can dial in the tuning better then Malone. I reach out to him with a PM and ask if he can tune my car

He takes a week or so to reply. Not a red flag or anything. Thinking he is busy. He has me fill out a simple form with the modifications I've made. Some testing of the turbo actuator and report results and health of the system. A few back and forths, and some logs for him to review. He sends me a first draft tune. Runs but a little rough. Too much smoke all around. Logs show severe underboost. Two more revisions after additional logs and I have a tune that I can drive. Good response and power down low until about half throttle . Then very little power and lots of smoke.

A few emails with updated logs for him. Explanations as to the issues. His replies are starting to become much slower. Excuses like being sick. Ok I get that. But then other excuses like family issues, sick again. Still promising to make revisions to the tune to fix the issues. Each reply being longer and longer between them. Now stretching into months between replies. Now over one year into the tuning.

Kinda giving up on him, I look into, once again, what it will take to tune it myself. Having a decent grasp of Duramax tuning. I figured I could learn to do my TDI and be done with all of this crap
 

2004LB7

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Part two, the fun

Since I've already purchased the MPPS and software to load the tunes from the tuner. I just needed software to be able to edit the tune files. After looking at multiple options, really wish Efi Live was compatible with the TDI as it would make things much easier, I ended up giving TunerPro a try.

TunerPro has some similarities to efi live V7 with the tables and tree structure of the table list. The 3D maps, etc. but much more basic with no smoothing tools or other user friendly options.

My first task was finding the tables for the tune. TunerPro uses an XDF file to hold the addresses and table information. Not unlike the CAX files of efi live. I paid someone on Reddit who said he could do it for $25. $25 later and I had a basic XDF with most of the important tables mapped out.

Like we all advise, I made a few small changes and tried it out. Mostly just going to and from work. Taking logs and seeing where it is running. Boost was still falling way behind in the upper half of the throttle.

The way a PD injector works is a little wild and very different then what we are used to on the Duramax. They are actuated by the cam. Sort of similar to the older style mechanical injectors. But instead use a solenoid to hold or bleed off the pressure. This is how the ECU can control timing. The PD injectors have less range of when they can be commanded to inject as they can only work within the confines of the cam lobe

The injector also has a weird pre injection (pilot) that happens as the cam pushes the plunger down. Them it closes and then when pressure raise high enough the main injection happens. The pilot timing isn't controllable and is mostly fixed and has a slight difference based on RPM since a faster cam will puch the plunger down quicker creating higher pressure. Because of this there is significantly more delay between commanded injection and when it actually happens

For timing I'm seeing numbers as high as 40° in the upper RPMs. The idle timing can be 4° or more. You have to account for approximately 1000 to 1500 uS in delay.

I was having trouble getting anything working. Still lots of smoke with little boost in the upper range

I decided to ask Claude AI to take a look and see if it can pin point what was wrong. Uploaded the bin and log file. It spits back a bunch of technical Jargon about how the boost is not matching the fuel. There is not enough boost for the amount fuel being injected. Ok. I already know that. Can you fix it? Yes, let me make new tables for you for your tune.

Looking over the changes. All it did was lower the fuel to match the [lack of] boost. Asking about this, it sates that the turbo is not able to keep up with the amount of fuel so it needs to lower the fuel until the turbo can keep up. ?????

Trying to get it to understand that it needs to fix the underboost issue. It agrees and gives it another try. Once again dropping fuel even more. Face palm.

Ok, lets start over. With the original fueling. Do the air to fuel ratio calculation to figure out how much boost is needed to match the fuel. Then make the changes to get the turbo to make the needed boost. Claude, oh, this is a good idea. This is exactly what needs to be done since there is no more guessing. Me - Eye roll.....

Third tune is not much different. Pour calculation of the vane tables and boost .

One benefit is the final Claude tune is smoke free. Downside is stock like HP

Alright Claude is out. Back to manually testing and tuning.

I did go back to Claude and ask it to find additional tables and fill in the XDF file with details and temperature ranges of the individual tables. This it actually did quite well

A few revisions and logs later, I got a decent tune. Good power all the way to the top. Little puff of smoke before boost comes on.

I'll try and update this thread with some screenshots of the tables and how the whole system works for a TDI
 

2004LB7

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So you were teaching AI how to tune 🤣

Do you know the flow rate of the injectors?
Trying to. But AI doesn't seem to understand the correct concept yet. Plus it can't drive the car and get real time feedback. But it didn't even make good use of the logs either. I bet in a few years it might make better tunes then we will ever make ourselves. I wouldn't be surprised if all the vehicle manufacturers go that direction

I don't know the flow rates as I bought a new set off another forum member who said he never installed them but had them in storage for a few years before deciding to go another direction. Didn't have the paperwork anymore from what I recall. They aren't over bored nozzles. But from what I gather they are the factory nozzles from the EU variant put on the US injector bodies. Flow should be identical. They also came from a well known and respected injector company.

Plus now having roughly 50k miles on them. I'm not sure flow rate sheet would match anymore.

Looking at the drive by wire website where these where purchased from. They are actually rated at +93% over the stock injectors. That's almost double. Interestingly I don't see any real numbers for flow like mm3 or CC. Might be because these injectors don't work like others and don't have a fixed pressure that can be tested at. RPM and timing will all play into the actual amount of fuel delivered besides the duration.

Infact, the tune doesn't even have any fuel pressure tables because there is nothing to control or monitor the actual pressure. There is an inferred table based on guesswork but doesn't do anything as far as I know.
 

2004LB7

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I'm actually thinking of letting Claude try and convert my XDF file to a CAX file so I can open the Bin with efi live. Then I can make all the edits there and copy/paste them into TunerPro for saving it. Since efi live won't save in bin format that I can use.
 

Lennydmaxguy

Just another diesel tech
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I'm actually thinking of letting Claude try and convert my XDF file to a CAX file so I can open the Bin with efi live. Then I can make all the edits there and copy/paste them into TunerPro for saving it. Since efi live won't save in bin format that I can use.
I wish it was that simple, but I don't think Efi live will let you load the BIN.
 

PureHybrid

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Maybe there's some high end AI that can write solid tune files based on user feedback and engine design data? As far as I know there isn't... Buddy that still works at a major OE, he works on fuel / timing based on live data and log files. Manual adjustments for the most part. He even complains about the AI program he uses to plot data needs a helping hand and several differently worded prompts.

As far as I'm aware, most unit injectors whether it be mechanical or hydraulic are still measured by total available fuel for 1000 strokes. Like you said, kind of weird to work with since it's a limited window
 

PureHybrid

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There is an AI tune software for HPTuners that is supposedly good. Only costs $75, thinking about giving it a try on a truck I already have tuned.
For gas and diesel? I can see that kinda working for gas, things operate within a much narrower window, although I can see it just jacking up the timing until it sees knock. Diesel operates on such a wide range AFR I don't see it doing a great job without an opacity meter in the pipe
 

Chevy1925

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Have you considered HP tuners?

You can only read and write. Hed probably have to buy the user defined parameters as well if he wanted to use vcm editor and get the bin file converted. Definitely more user friendly than efi live at this point though
 

2004LB7

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Have you considered HP tuners?
not really. didn't want to put out too much expense on this on. was originally just an experiment as I had no idea if I was going to be able to do it. and it looks like TunerPro is more then capable. just wish I could use some of the nice tools in efi live. but copy paste works for now