Pedal Ratio Map on Ecoboost files

[bmpcamry09]

Just wanted to make a quick informational post about the Pedal Ratio Map on this platform. Not a ton of information out there on it, so I decided to do a bunch of testing to learn more about it. If anyone else has more information to add, please do so! There could always be something I am missing.

I have noticed a few of the big name tuning companies have a significantly more torquey feel down low around town and low APP scenarios, but they use progressive pedal translation instead of a mounded type of translation (think pedal commander, Cobb AP throttle maps, etc....)....More specifically, I am certain that the PRX files from MPT have quite a bit of pedal map ratio changes in them based on feel and datalogs, but I can't confirm that as all my files from them are locked, understandably.

I discovered that this torque surge has almost everything to do with the Pedal Ratio Map and Driver Demand table. I always tweaked throttle response with the normal "pedal translation" area, but I think if you can master the pedal ratio map, your customers will like your files a lot more and you can leave the pedal translations alone so that your RPMs stay in the power band better.

It appears the numbers in the Pedal Ratio Map are multipliers. For example, if at a throttle application of 20 percent and an OSS of 500 (right off the line basically), your factory settings has a .8, then it is taking whatever driver demand number in your normal driver demand area and multiplying it by .8. So if your DD table shows 150 ft. lbs at 1500 RPM at 20 percent APP, the true DD is actually going to be 120.

Now this said, you HAVE to be careful with how you change this table. Some spark table and turbo tables may have to be adjusted around this, as if you add in more commanded torque, you may fight some KR or turbo surge. I learned that leaving the two outside columns stock but adding 15-20 % to the remaining ones, and then smoothing all, REALLY helps in town power delivery and overall refinement to the driving experience. If you add to the last columns, I imagine your requested torque will overshoot actual and won't be helping.

15-25% over stock from an OSS of about 500 seems to be the sweet spot for 91 octane and up files. 5% seems to be the sweet spot on 87 octane without having to tweak spark tables to reduce KR.

Depending on how much you add to the ratio map will also determine if you need to raise maximum torque and maximum MAP value in your IPC tables. I just raise them all by whatever percent I raised the ratio map.

Another thing to keep in mind is if you add in torque down low, consider adjusting your transmission to behave better with the new found low torque. The 3.5 vehicles I have been testing this on love to be around 2500 RPM with the added torque. Keep LSPI tables reasonable to combat KR. For reliability reasons, try not to push over 15 PSI until your north of 2000 RPM.

To some of the more educated folks out there, please provide further insight. I really want to know if the transmission adapts to these increased torque values, or if only adjusting the values in the normal DD table would be better???

[Rob@HPTuners]

On the calibrations that are equipped with this, it works as you suggested. Multiplies the torque request coming out of the driver demand. It just provides another axis of granularity since the Driver Demand table doesn't have OSS as an axis. This is a fairly common way to create what is effectively a 4D lookup table. This should propagate directly into your torque request and should be reflected in your log, so in that sense, the transmission and everything else will respond in the same way that it responds to any change to requested torque. All of the limiters should also still be in play.

How you adjust it is really up to you. If you multiply a request at 50% to output the same torque that's at 60% in the DD table, you're really just changing pedal feel, and there really shouldn't be too many tuning considerations. It's the same safety consideration as if someone had just mashed the pedal at that given engine operation condition. However, if you're raising the torque requests beyond the maximum that the stock tune would see at any given OSS or RPM, then you're into new territory (more boost, more torque, etc.) and then all your standard tuning considerations apply. I don't see the IPC MAP values changing unless you've gone way off the end of the table. More torque request = more load = more MAP, and that table already references load.

TLDR; It's all pedal feel stuff until you raise above the maximums

[bmpcamry09]

Exactly the reply I was hoping for. Thanks Rob!