Diagnostic Limits

Hello everyone,

After a recent lifter failure that took the head out on my ALH, I have put a new low km motor in it along with pp764, vnt17vb and a self made intake manifold and fmic with 2.5 inch pipe (too much TIG welding!)

I have been doing some tuning and would like to avoid setting my pump voltage high and having an un-calibrated pump voltage map. Currently I have everything figured out except the 51 mg diagnostic limits.

I have current diag limits for boost set to 3060, to go along with the 3 bar map. I found the maf by temp map in the file and set the axis and values for the upper axis value to be 1500, though the diag limit is still set to 1250. I also have found all the 27 33 hex values for iq limits for internal ecu use.

I have been reading on here and ecu connections for 2 days and cant seem to figure out how to raise the MAF and IQ diagnostic limits from 1250 and 51 mg/stroke. I know there are some brilliant minds here so if anyone could give me a hand (PM works too) that would be really great.

-Mike

on the MAF I have no idea how to get past the 1250 limit, other than dividing the MAF linearization values by 2, then multiply allowed fueling in smoke maps by 2
Gets around the limitation. You might max out the maf body at higher rpms though

on the fuel diag limit, I've seen people able to raise it to something around 70mg/str, but the computer accepts but doesn't display values higher than that. On mine I just multiplied driver's wish, smoke, tq limit, pump volt map, and maybe a couple others by 3 so now it goes from 0-153mg/str.
vcds still says a max of 51, but that doesn't matter

There's no such thing as an accurately calibrated pump voltage map.... without ultra expensive laboratory equipment.

Treat 50mg (or 51mg) as 100% / 5V on pump duration, and scale everything else around that.

Looking at bigger calculated numbers will not give you more power.

Yes, I had my maps set up as 51 mg/st was actually much higher. Pump voltage is what matters, I get that. That said, I don't want to tune it that way. I know it is possible to read much higher than 51, that seems to be the lazy mans way out. Weather 50 mg in my file at x rpm is 48mg or 52mg or whatever it is nice to have it much closer than 100 = 50.

Also, I do quite a bit of tuning on gas engines. I have a wideband, and it has datalogging. It reads to 100:1 AFR down to well below 10. Knowing MAF and AFR it is not difficult to set up a pump voltage map *properly*. After all, MAF/AFR = IQ.

486, How did you get it to read 70 mg in diagnostics?

millerlite said:

486, How did you get it to read 70 mg in diagnostics?

Click to expand...

I didn't, robnitro did
mine just sits at 51 just about any time you're on the go pedal

oh, btw, the numbers derived from the p/v map aren't accurate with the different injectors

you could set up your pump and injectors on a source of variable RPMs (I'd use a gearhead lathe with a VFD) and use a function generator to put power to the QA for a specified time (calculate out 1k injection strokes at that pump RPM) and then catch the fuel that comes out of the injectors in either a burette or just weigh it
do it about a hundred times and populate your p/v map with real values

or just say F it all and ignore the smoke at certain transient places. Won't be able to get rid of the puff of smoke on spoolup anyways with as much air it takes to pressurize a bunch of 2.5" pipe and an FMIC, unless you just run really lean all the time.

I'm still somewhat interested in what others have to say about raising diagnostic limits just from a purely academic standpoint.

Enabled said:

Treat 50mg (or 51mg) as 100% / 5V on pump duration,

Click to expand...

in pump voltage map you do not want 5v, there is a factor to the map, iirc you end up with around 4.7ish v max or you'll get limp mode when it requests over 5v to the QA

Right on, I'm actually using robs pump voltage map currently as I still need to weld a wideband bung on my downpipe. I have the same 11 pump and nozzles setup as him. There is no need to measure fuel from the pump when you have AFR data. As I said, drive the car and take logs of AFR, pump voltage and MAF. Its really that simple...

Lets say (just random numbers) you have a maf reading of 1000 mg/ st and pump voltage of 2.540 volts, AFR on wideband reads 28:1 and your ar 2500 rpm:

you know with 1000 mg/stroke air, fuel is 1000/28 (afr) = 35.7 mg/stroke fuel.

Now, in the pump voltage map you can go to 36 mg column, 2500 rpm row, and enter 2.540 volts (or 2540/1.22 decimal)

Since SOI is going to throw off your pump voltage map I plan on getting it close before taking all my wideband data, and then tweaking the SOI maps and retesting to verify any change.

You all might think I am crazy but I like doing things the best possible way I can...

-Mike

[486] said:

in pump voltage map you do not want 5v, there is a factor to the map, iirc you end up with around 4.7ish v max or you'll get limp mode when it requests over 5v to the QA

Click to expand...

Yes there is a conversion factor, of some 1.22 or so (off the top of my head). My 51mg is at exactly 4.99V to pump. No errors.

While it would be very cool and awesome to get an actual mg fuel use, especially for consumption calculations... it's just not worth the hassle for me. (It's not worth the hassle for any of the major tuners either...)

My TDI is right where I want it after over 60 flashes, so no more.
I just added a 2014 328d that I will need to figure out.



I tune more gas than diesel, almost exclusively BMWs from mid 90s to mid 2000s. Including a few active endurance race cars.
Gas tuning is completely different, and I understand where you're coming from.

I flashed mine well over 100 times in the past 5 years. I had mine set up like you for ages. Id rather have it correct personally. Major tuners don't calibrate voltage maps because they cant. Too many variables from car to car including quantity adjuster position. It would never be correct unless they set up a wideband on each individual vehicle.

I am aware of the conversion factor, like I said above. 2.540 v = 2540/1.22 in the map.

I am asking about diagnostic limits, I am not looking to explain why I am doing things the way I am doing them... I am looking for the diagnostic factors and message numbers used that need to be changed to read more than 51 mg in vagcom. My voltage map already goes to 80 mg/st and the computer can use the whole thing internally. I can watch the pump voltage go up while vag still displays 51. Those internal limitations were easy to find, there are 7 per codeblock, just search 39 51 (27 33 hex).

I am not new to TDI tuning, and in the past I used the same strategy as you. But I want to figure this out! I'm sure that if this was an easy straight forward task you would be setting your voltage map up properly too. I actually enjoy the theory and relitive complexity behind the TDI

Think I have this figured out. I will post a small how to here for edc15vm when I have some time if anyone is interested.

-Mike

<- interested

You should find in 8bit dec 039 051 (7 times, make sure you are in the correct codebank) and change them to whatever you want for example 039 075 for 75 mg, but this is not all, you should also correct the factor now - Steigung fuer Diagnose Umrechnung Mengen. In edc15vm it is 500, because of 51mg -> 255/500 = 0.51
So for 75mg it will be 255/0.75 = 340
I can't tell you about MAF, because I made my car to run on MAP and never was interested in MAF corrections.

Ive done this on my AFN 110bhp tdi.
All the info is on EcuConnections website, if you search for user brum who also has an AFN engine. It'll give an indication as to which values to change to read above 51mg - you then just need to find the equivalent values on your ECU, but shouldn't be difficult

iirc this is all in the edc15 tuning guide pdf, but yes branching off to other parts of the internet besides tdiclub is a good idea also. Not that you really need it as others have pointed out. But I agree I want to see what it is actually pushing.