For Tuning Gurus: tuning requirement differences between '09 & '10 CR and BRM PD

OK, let me first say, I am very aware of the fact that there are numerous threads running around about the basic differences between the new common rail TDI and the older BRM PD.

My question is slightly different. I would like to know the difference between the two engines from a tuner's perspective.

1) What would a tuner need to do differently to tune a CR than what he did for the BRM PD?

2) from my limited knowledge of tuning, a tuner would probably be modifying the injection timing, fuel injection, boost, and possibly EGR. Would the tuning for both of these engines deal with the same parameters, or is it possible that the CR would have more parameters which would need to be dealt with?

3) It is obvious that dealing with the DPF regen cycles is a big issue for tuning the CR...would this be a whole different area of tuning when compared to the tunes for a BRM, or would it just involve further modifications of the existing parameters?

4) anything else I missed?



If I could just get some input on this, it would be great! Please be gentle with me, I do know that there are many threads about the basic physical differences between the two engines. My only interest right now is how the differences between the CR and BRM PD would create different tuning requirements.

well, I do know that the 09 and 2010 have the same Commonrail engine..

The BRM (similar to the BEW) is a totally different animal that has an appetite for camshafts.. I have a BEW here with a bad cam as I type this..

F250_JR said:

OK, let me first say, I am very aware of the fact that there are numerous threads running around about the basic differences between the new common rail TDI and the older BRM PD.

My question is slightly different. I would like to know the difference between the two engines from a tuner's perspective.

1) What would a tuner need to do differently to tune a CR than what he did for the BRM PD?

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On a CR engine, fuel flow will be based on injection quantity which correlates to an injector open time and a corresponding rail pressure value which will dynamically increase with load and RPM.

On a PD, injection pressure and volume is much more fixed. IQ is altered via injection duration (open time).

The CR is much more flexible, and really required for the regeneration functions to work.

F250_JR said:

2) from my limited knowledge of tuning, a tuner would probably be modifying the injection timing, fuel injection, boost, and possibly EGR. Would the tuning for both of these engines deal with the same parameters, or is it possible that the CR would have more parameters which would need to be dealt with?

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Broadly speaking they are the same thing, but the CR engine will likely require more in-depth research and testing to ensure that the emissions system remains fully functional for as long as possible. It is currently possible to delete the dpf....

F250_JR said:

3) It is obvious that dealing with the DPF regen cycles is a big issue for tuning the CR...would this be a whole different area of tuning when compared to the tunes for a BRM, or would it just involve further modifications of the existing parameters?

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Ideally, the best scenario would be that particulate matter wouldn't drastically increase and all regeneration parameters would remain as they were. If it only causes an extra regeneration event every once in a while, then no big deal. We just can't have it clogging up constantly and causing constant regeneration events which wear out the dpf.

F250_JR said:

4) anything else I missed?

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That would depend on what you're looking for here. If you want a subtle increase then I think it is very possible with all of the emissions equipment in place. If you want big power, then the dpf is going to have to come out and you're going to have to get a bigger turbo. Also, don't expect to put a huge amount of power through the DSG trans.

I'm curious as to what power levels the 2.0 CBEA fuel system is capable of supporting in a track car with giant turbo, open exhaust, etc... Just how much will those piezo-electric injectors flow???

Farfromovin said:

I'm curious as to what power levels the 2.0 CBEA fuel system is capable of supporting in a track car with giant turbo, open exhaust, etc... Just how much will those piezo-electric injectors flow???

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I don't have an estimate for you. But, fuel flow possibilities are somewhat open ended. There are some common high pressure pumps that could be used in place of the stock pump, and upgraded nozzles aren't really such a problem.

F250_JR said:

My question is slightly different. I would like to know the difference between the two engines from a tuner's perspective.

1) What would a tuner need to do differently to tune a CR than what he did for the BRM PD?

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Almost everything.

With a BRM and all of the prior P-D or rotary-pump cars, at a given RPM and load request, there was a definitive single injection quantity and a definitive injection timing signal (and an EGR setpoint and boost pressure setpoint and so on).

With the common-rail engines, you have multiple operating scenarios. The engine could be running normally, or it could be initiating a DPF regen, or it could be doing a de-NOx regen, or it could be doing a de-H2S regen, and all of these require different parameters ... but the driver expects the same response to the accelerator pedal regardless of operating mode. So, you have multiple sets of operating conditions that are all expected to smoothly blend so that the driver doesn't notice. That's hard to do.

F250_JR said:

2) from my limited knowledge of tuning, a tuner would probably be modifying the injection timing, fuel injection, boost, and possibly EGR. Would the tuning for both of these engines deal with the same parameters, or is it possible that the CR would have more parameters which would need to be dealt with?

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The North American spec common-rail engines have a second low-pressure EGR system. The complication is not that these things need to be controlled. The complication is HOW they are controlled for doing all the emission control functions.

F250_JR said:

3) It is obvious that dealing with the DPF regen cycles is a big issue for tuning the CR...would this be a whole different area of tuning when compared to the tunes for a BRM, or would it just involve further modifications of the existing parameters?

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I have no idea of the contents of the engine controllers, but I'm thinking the EDC17 controller in the common rail engines has a WHOLE lot more memory and a lot more processing capability.

The new engine controllers use a torque-based algorithm with mathematical models of the engine response. At a given RPM it interprets accelerator pedal input as a torque request. Then it figures out how to produce that torque depending on what operating mode it is in (depending on regeneration strategies). Simple ... it ain't.

GoFaster said:

The new engine controllers use a torque-based algorithm with mathematical models of the engine response. At a given RPM it interprets accelerator pedal input as a torque request. Then it figures out how to produce that torque depending on what operating mode it is in (depending on regeneration strategies). Simple ... it ain't.

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Most of the EDC16 based controllers also work based on torque instead of fuel in milligrams and such. At some point there is always a conversion of sorts though.

Thanks guys...I knew you would give me plenty to chew on.

If I am understanding correctly, tuning for the two engines would remain basically the same (working with the same parameters), but the tuning for the CR would be more complicated, and deal with multiple engine operation scenarios (to handle different stages of regen cycles, etc.).



So, how compatible would tuning software written for one engine be as a baseline for writing the other engine's software? Example: I have already written tuning software for the PD engine, and now want to tune the CR...what's involved with using my existing software as a baseline for tuning the CR?

Or, the opposite scenario: I have just written software for the new CR, and now want to include the older PD's in my tuning capabilities...what's involved with using my existing software as a baseline for tuning the older PD's?

Thanks for being patient with me guys...just trying to really understand the differences we are dealing with here. You're all helping me a lot!

I'm not entirely sure what you mean by using one as a baseline for the other. But, in the PD's you will find some similar maps to the CR engine, but then many that aren't there....then some others that are in the CR and not in the PD. There will likely also be differences in the single value limiters and such.

The software versions themselves are in no way interchangeable or compatible with each other. You'll find that they're both 16 bit base 10 and have some similarities as Bosch has a propensity to organize and group things in certain ways. If you're trying to talk specifics here then try sending me a PM.

vwmikel said:

I'm not entirely sure what you mean by using one as a baseline for the other. But, in the PD's you will find some similar maps to the CR engine, but then many that aren't there....then some others that are in the CR and not in the PD. There will likely also be differences in the single value limiters and such.

The software versions themselves are in no way interchangeable or compatible with each other. You'll find that they're both 16 bit base 10 and have some similarities as Bosch has a propensity to organize and group things in certain ways. If you're trying to talk specifics here then try sending me a PM.

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I'm not trying to get too specific...I honestly don't know enough to get very specific. I have just heard people mention the possibility of tuning the CR first, then later tuning the PD using the CR tunes as a "baseline" for the PD tune. I was curious, so I thought I would explore exactly what would be involved in doing this. I am assuming that using one as a baseline for the other would mean just using the modified maps for the CR as a starting point for modifying the PD maps.

Hope I'm not stepping on your toes here man, just trying to look into some stuff I heard about, and learn more about tuning in the process.

F250_JR said:

I'm not trying to get too specific...I honestly don't know enough to get very specific. I have just heard people mention the possibility of tuning the CR first, then later tuning the PD using the CR tunes as a "baseline" for the PD tune. I was curious, so I thought I would explore exactly what would be involved in doing this. I am assuming that using one as a baseline for the other would mean just using the modified maps for the CR as a starting point for modifying the PD maps.

Hope I'm not stepping on your toes here man, just trying to look into some stuff I heard about, and learn more about tuning in the process.

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If you can tune one, then you will probably more easily understand the other. The learning curve won't be quite so steep that way. But, one has relatively little to do with the other. There is no question that the CR is much more complicated to work with which really comes as no surprise given that it is a more complex ECU which controls a vastly more complex emissions system. That's probably about as concise of an answer as I can offer given the vague question

Even negating the exhaust treatment there are more variables with CR. More pre- and post- injection possibilities, plus the ability to command any desired rail pressure at any rpm/torque combo.

Yes, that's true also. With PD's and rotary pumps there was a "start of injection" i.e. injection timing. With common-rail ... Let's see, shall we inject all the fuel in one shot, or in two? Or three, or five? And does the first shot get 10% of the total, or 30%? And what of the second shot? And how much delay between injection shots ... And the transitions between running in single injection shot mode and running in two-shot mode are of course expected to be seamless to the driver.

I have a funny feeling - but no first-hand knowledge by any means - that the various "performance tuning" that is starting to show up for the common-rail engines, is only addressing a small fraction of the whole picture. They're probably leaving all of the part-load and regen-mode programming alone.

vwmikel, thanks for being patient with me. I really do appreciate all of you working to answer my "vaque" questions. I do try to stay specific, but it is hard when I am still in the process of learning basic concepts. I think I understand the difference between the two engines better now, as those differences relate to tuning.

Brian, it is very interesting what you say about the current tuning for the common rail TDI's. It is definitely something for new TDI owners to consider, and it makes a lot of sense.


Thanks again guys! I am slowly picking up some good knowledge about tuning and related issues. The way I look at it, I do want to increase the power on my vehicle, but I also look at TDI ownership as an excuse to further my knowledge of engines and diesels.

The objective of chip-tuning being to increase the power output over stock levels, the part-load mapping is usually not touched unless to fix some undesired characteristic found in the factory tuning.

At full-load, many of the aforementioned variables are would be in play at part-load do not apply at full-load. For example, at high-load, high RPM, the fuel injection strategy goes to a simple single injection instead of having up to 5, 6 or 7 injections per cycle. DPF regeneration is usually not a concern at full-load because the exhaust gas temperature is sufficient to maintain self-regeneration of the DPF, as long as the tuning does not go too far and operate the engine at conditions that generate too much soot and prematurely clog up the DPF at a faster rate than can be regenerated. EGR, particularly the high-pressure (short path) is not functional at most full-load points. Ditto the de-NOx and de-SOx processes, which require momentary operation at Lambda < 1 via throttling the intake, are also not active at full-load.

So, tuning for the CR TDI, particularly the North American-spec version, is not such the black magic that some make it to be. The challenge is in modifying many more maps and parameters in the EDC17 than in any previous ECU generation than simply fuel quantity tables. It may also involve finding work-arounds around the ECU expected values and requires lot of knowledge of model-based control.

TDIMeister said:

...So, tuning for the CR TDI, particularly the North American-spec version, is not such the black magic that some make it to be. The challenge is in modifying many more maps and parameters in the EDC17 than in any previous ECU generation than simply fuel quantity tables. It may also involve finding work-arounds around the ECU expected values and requires lot of knowledge of model-based control.

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That makes a whole lot of sense. More maps=more complicated and in depth tuning, because there are more maps to modify.