What steps to dial in a tune?

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mgoff5000

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2000 Jetta, 2004 Passat (RIP)
I realize the answer to this may be "take it to a tuner" but I've got a VCDS and tools so I'd love to optimize my Malone Stage 3 myself if I can. I've reached out to Malone and they've been helpful, but understandably there are limits to how much they can provide in terms of detailed guidance.
Background:
- 2000 Jetta TDI
- Swapped nozzles to DLC1019s myself. I did not get them pop-tested, balanced or anything else. If that is heresy to you, then let us part ways here ;)
- Upgraded clutch to G60/VR6 myself
- Put on Malone Stage 3
Initial Results:
At first, torque was really good.
Current situation:
Fun to drive, but much diminished from what I recall of initial results. Get lots of black smoke but not as much accompanying "oomph"
The IQ at idle is around 5 mg/str. Injection timing is advanced to just inside normal limit. Logs usually requested by Malone are here:
Block001
Block003
Block004
Block008
Block011
Main question is whether anything jumps out from these logs and if there are other obvious logs to take? Seems with VCDS I should be able to at least locate what element of the system is off.
Thanks for any input!
 
Last edited:
Kevinski4

Kevinski4

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Your logs show us that you have the same power as you did before, you likely are just getting used to it. You have full fuel and full boost. Lengthen your VNT actuator rod one turn and re log Group 11. It's not bad, just has some room for improvement on the mechanical side of things. That will smooth out your boost curve and make power delivery smoother.
 
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mgoff5000

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Yourbuddysatin said:
Your IQ is at 5 and it dumping black smoke?
Click to expand...
Yes, although it may be the expected amount of smoke for this tune as I have no reference point. Malone was kind enough to also send me a Stage 2 to try out so I can check smoke on that one for comparison. Their guidance was to expect a "brown haze" after a black puff on spool up. However, I get a decent amount (embarrassing in the land of Tesla) of black smoke at WOT though.
 
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mgoff5000

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Kevinski4 said:
Your logs show us that you have the same power as you did before, you likely are just getting used to it. You have full fuel and full boost. Lengthen your VNT actuator rod one turn and re log Group 11. It's not bad, just has some room for improvement on the mechanical side of things. That will smooth out your boost curve and make power delivery smoother.
Click to expand...
That could very well be the case. Thanks for the suggestions. Can I ask a couple questions along those lines?

Is the "full fuel" based on hitting 50 mg/str requested by ECU? Or is there another way to determine how much actual fuel is being delivered? i.e. what would be see if there was a clogged fuel filter and the requested fuel wasn't getting delivered? I'm assuming black smoke means there's fuel, so just trying to understand what VCDS can help us pinpoint.

On the actuator, I want to check if we're seeing the same control issue on Block 011. What I see is the delivered pressure tracking really well to the N75 %, however the ECU is doing a crap job of controlling the N75 with respect to the desired boost. Specifically, the N75 isn't letting off until _after_ the actual boost exceeds the requested despite a clear trajectory of building pressure. I would think lengthening the rod would lead to a different N75% for a given pressure but not necessarily change the shape of the spike and recovery. Can you elaborate on that a bit.

Thanks again, really appreciate you taking a look at the logs!
 
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Yourbuddysatin

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In my opinion if the IQ is that high I don’t think it should put out very much smoke at all. I have stage 4 and run around 2.8-3.2(fluctuation) and it doesn’t not dump a lot of smoke. When I had it at 2 it was a noticeable cloud though. I could be wrong though.
 
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mgoff5000

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Yourbuddysatin said:
In my opinion if the IQ is that high I don’t think it should put out very much smoke at all. I have stage 4 and run around 2.8-3.2(fluctuation) and it doesn’t not dump a lot of smoke. When I had it at 2 it was a noticeable cloud though. I could be wrong though.
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I'm still trying to build my understanding of the idle IQ, but I think it just amounts to an arbitrary number assigned to the fueling required to maintain idle.

Compared to the max fueling of 50 mg/str a lower idle IQ allows more "room" to build fuel up to that maximum. In that context I don't think 2-3 mg/str difference compared to 50 mg/str is that significant. (but obviously, lower idle IQ allows for more fueling)

I suspect there is some element of this I'm missing because people do talk about these small adjustments to IQ in the context of smoke/power quite a lot.

I think it also must depend quite a lot on your injector nozzles. I believe everything works on pump voltage and the corresponding fuel pressure. So I think the mg/str is a calibration relevant to stock nozzles. Unless the tuners change that calibration (Malone knew I had DLC1019s) then the actual fuel delivered for a given pressure is going to depend on the nozzle aperture. Not sure on that, just guessing on basic engineering principles and my understanding of the system components.
 
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Yourbuddysatin

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It must make a difference because the higher at idle the better mpg you will get. DBW told me to set it around 5 to get optimum fuel mileage after my nozzles were done.
 
Kevinski4

Kevinski4

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mgoff5000 said:
That could very well be the case. Thanks for the suggestions. Can I ask a couple questions along those lines?

Is the "full fuel" based on hitting 50 mg/str requested by ECU? Yes Or is there another way to determine how much actual fuel is being delivered? i.e. what would be see if there was a clogged fuel filter and the requested fuel wasn't getting delivered? If requested fuel was not being delivered, you would not be able to hit full boost. No fuel, no boost. I'm assuming black smoke means there's fuel, so just trying to understand what VCDS can help us pinpoint. Your stage 3 tune is squeezing every last bit of power possible out of the stock turbo. There's gonna be some smoke.

On the actuator, I want to check if we're seeing the same control issue on Block 011. What I see is the delivered pressure tracking really well to the N75 %, however the ECU is doing a crap job of controlling the N75 with respect to the desired boost. Specifically, the N75 isn't letting off until _after_ the actual boost exceeds the requested despite a clear trajectory of building pressure. I would think lengthening the rod would lead to a different N75% for a given pressure but not necessarily change the shape of the spike and recovery. Can you elaborate on that a bit.ECU/N75 is doing exactly what it should, but the actuator rod is too short. The ECU "thinks" the vanes are in a slightly different position, hence the big spike and overcorrection. These old cars have very little computing power compared to current models, so the 'actual' boost response will never be 'perfect'. You are right that the N75% will change. You want it to be about 80% across the upper RPM range. Messing with rod length makes a HUGE difference in the shape of the spike/recovery. Start with 1/2 turn. May end up needing one full turn. Doesn't take much, go too long and the spike can be eliminated entirely but it will make the turbo very slow to spool.

Thanks again, really appreciate you taking a look at the logs!
Click to expand...

Reply in bold blue.
 
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mgoff5000

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Kevinski4 said:
The computer thinks the vanes are in a different position..
Click to expand...
OK, may give the rod length a tweak next time I'm in there. At least that's on top of the turbo. I do not particularly enjoy working on the turbo while on the car!

In terms of understanding this better, I notice the MAF spike is a bit more exaggerated than the boost spike. (although the same shape) Am I correct that MAF is on the low-pressure side of the system and sort of irrelevant if we're hitting the desired boost numbers?

If this matters, 3rd gear WOT is where I'm totally underwhelmed with the torque at this point. That's why I was suspecting fueling. And that's why perhaps I'll carry on with the hammer mod down to IQ 3 to see if those couple mg/str have much impact. (on power or smoke) I've hesitated on the hammer mod because I've paid the bill for a new IP already and I'd feel pretty stupid if I paid that again.
 
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mgoff5000

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Curious Chris said:
You still have the MAF controlling the fuel? My RC4 puts the MAF at 850 solid.
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Not sure. No idea if ECU allows for this or tuner uses it.

I'm looking at MAF from a diagnostic perspective. I've read that diesels are always fuel limited so I'm assuming as long as there is enough air it's fine. I wanted to know if the big spike above requested MAF would have a negative impact on performance.
 
jmodge

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