That's what is so funny, they don't use DD at WOT but it was DD that was causing the issue.
That's what is so funny, they don't use DD at WOT but it was DD that was causing the issue.
Can someone show me where it says DD is ever disabled? http://www.google.com/patents/US6367447 I found this patent and it seems to have similarities to the 15+ manual vs automatic pedal operations.
which is exactly why I recommend leaving the base torque model stock (or as stock as possible) unless you have drastically altered your airflow characteristics....you have a stock engine.Originally Posted by rhinogt
this was a long hard lesson learned dealing with my corvette. the torque based pcm and direct injection is similar in a lot of ways to the ford and even on those, the driver demand table (and VE and MAF tables) define a relationship between airflow, pedal position, and torque production.....
lb/min = power and the more air you move the more power you make
pedal = power and the more you push it the more power you should make
if you have changed your DD table in a way that commands too high of a torque in the middle vs what it says up top, it thinks it is past the point of most power and screws itself up. I have yet to encounter a vehicle that "needed" the DD table altered. My DD table on my C7 is stock (except for the 100% row as they use DD at WOT) and it's a 416ci stroker with a blower....the rest of the torque model will reference the airflow model to determine the torque output so if your airflow tables are right, your output will also be right.
bumping the DD table is just a hack and doesn't always turn out as expected.....and yes, there are a lot of hacks and rapes going on in "pro shops." of course then we teach each other the wrong way to do it.
baking wot error into PE tables, baking fuel system error into the airflow model and also baking in crap into the torque model now....
who says it is ever disabled?
if you are referring to my post, I didn't say disabled, I said it wasn't used, which might also not be the best terminology. it's still part of the torque model so it will always be referenced. big difference between referenced, used directly, and disabled.
Ok maybe disabled was the wrong word, but going over the tables I see now why they are not used.The manual cars go to 90% and the automatics go to 83.3%. I thought it was 83.3* as most of the other parameters in degrees are 83* to 90*. looking at launch, low range, and pedal map ratio it has to be %. % also makes more sense for describing pedal movement. Degrees makes more sense for moving a butterfly.
Looking in editor, the WOT pedal enable stock is set to 83.33 on my car. And by the definition listed by HPT, that is the rpm at which the ECU starts disregarding the DD tables. Well if you look at the DD tables, at least on my car, the pedal position goes from 64 degrees to 90. So at 83 degrees when it supposedly starts disregarding the DD tables, the ECU has to interpolate the torque demanded between 64 and 90. Like I said previously, it is the wrong way to do it modifying these tables, it was just something I had tried out.
Therefore, where I had the DD tables set at 64 and 90 degrees, were an impossible torque value for the car to achieve. And therefore, I assume the ECU was telling me that it didn't have enough fuel to make that torque. Hence the insufficient fuel flow I was getting. My theory may not be right but that's what I'm going, atleast until someone smarter than me figures it out.
Insufficient Fuel Flow. The PCM is saving you from running out of injector.
Eric Brooks
HP Tuners, LLC
However, a stock configuration will not run out of injector.
I to just experienced insuff fuel flow in my basically stock 2016 M6. I have tweaked my DD tables just playing around in search of crisper throttle response. I have changed lower and mid areas around 5-7.5% and currently pretty ear grinning part throttle acceleration. My first experiment will be to change back the 64/90 pedal position back to stock and do a couple pulls. I think it was briefly mentioned but I might try tweaking my Normal Drive Mode pedal input% vs output more. Currently set it as what the "sport/track" would have. I notice a little difference before I changed the DD but not as significant. Thanks guys.
From scan went to insuff fuel flow around 5200rpm. Throttle dropped but only 2%. Fuel flow was at 174lb/hr. .84 lambda. 35.7 lb/min MAF. Torque source DD.
Last edited by RSlo; 06-01-2016 at 07:10 AM.
Once I returned the driver demand tables to stock it went away
Did you change the complete DD tables back to stock or just the 64/90 throttle row? I'm really liking part throttle response with the changes I made in the lower areas. Hoping to make a WOT run tomorrow with the 64/90 throttle areas stock to see what I get.
In all honesty I couldn't tell you right now. I want to say I dropped the 64/90 tables and then interpolated the rest to smooth it out in part throttle. But I also dropped WOT pedal start to 70 which based off of what we know about the logic, means that the car uses DD tables less closer to WOT. Because 64-90 degrees is a big jump for the computer to interpolate when it comes to torque demanded.
With stock start and end pedal set to 83.3/90 in all of my WOT data logs torque source is always DD. Now according to HPtuner description it should disregard DD tables at WOT. If I drop my start % to 65 or 70 would it then disregard DD? What would it reference besides DD? Thanks.
It will still show driver demand even after you do that.
If raising DD causes issues, wouldn't that point to an issue someplace else in the tune though? The DD table is just requesting a certain amount of torque. The torque tables should still limit how much torque is applied to the wheels. The actual torque scheduled should be the lowest of either the DD or torque tables from my understanding. If the DD requests a ridiculous number, and the car acts funny, something must be up and the ECU is now ignoring the torque tables or is configured to ignore them. Putting DD back to stock and having it work seems like a band-aid to me. It's just masking some other tune issue that could still present itself. I think murfie is on to something with the ECU defaulting to speed density.
I know this is non-EcoBoost, but if the DD table is ignore at WOT (with the WOT start pedal value exceeded), then why are they telling us to modify DD for the EcoBoost engines to request more torque? Do we just keep the DD stock while trying to increase boost?
Sorry to necro this thread, but quick question for Higgs:
Can you provide any guidance on what engine modifications would alter the airflow characteristics enough to warrant a revision to the DD tables? Obviously LT headers and CAI 'can' change airflow characteristics at certain RPMs but are those mild airflow deviations compared to forced induction and/or camshaft swaps?which is exactly why I recommend leaving the base torque model stock (or as stock as possible) unless you have drastically altered your airflow characteristics....you have a stock engine.
Thanks!
Austin
A better explanation is that unless the volumetric efficiency model of the engine has changed, leave the torque/inverse torque tables stock. I see a lot of tuners messing with these tables on an otherwise stock engine! I tried it once on my SHO (EcoBoost) and all it does is try to trick the engine into demanding a higher airload at a lower throttle position. This was a "Band aid" solution when a lot of the torque limiters weren't unlocked in HPTuners. This would cause a very fast rise in boost until it ran into a limiter or worse you would cause a failure mode resulting in the wrench icon, and you chugging along at severely reduced boost and power on the road.
Different headers, cold air intake, and exhaust systems do not impact the VE model very much if at all. I'm not too sure on camshafts though, but my experience has been that cams just shift the powerbands around and not increase your VE.
Different cylinder heads, different pistons, stroker kit, a new forced induction setup (aftermarket blower/turbos, or bigger blower/turbos) would require changes to those tables.
Cams can effect VE a decent bit. If you do not see much of an increase with a much more aggressive set of cams there is likely a restriction somewhere else.
If LT headers and CAI don't impact VE significantly, aside from MAF transfer function and the UEGO time constants, what else needs to be touched in the tune to optimize their addition to the stock tune file?
Having read the LaSota Coyote Cookbook, I really like that gave a reasonable explanation for what most tunable parameters in the system do (though very little on VCT, distance tables, etc.), but I wish it gave more direction on "what to touch" given the following modifications beginning with "these things can be improved upon over stock".
As a novice tuner, I'm caught somewhere between the poles of "Ford spent a lot of time doing these things right the first time so don't mess with it" and knowing that name brand tuners advertise getting XX more hp and YY more tq over the stock tunes and those gains just amplify as additional engine hardware is upgraded.
Is there a better resource/book that I could dig into for understanding where to poke at in the tune for my given set of mods?
thanks,
Austin
Reply With Quote