Smooth Throttle for UpRev
 

Update - the old top post was wiped out in favor of new, better data and a better map. If you saw/used the map that was originally here, that map is what's called "Linear" below.

This post is all about the Throttle map in UpRev. You'll need the Tuner license (or take this data to a tuner) to use this. Keep in mind this is all from an NA vehicle with a fairly maximal set of bolt-ons and a dyno tune. YMMV on a bone stock car, and I especially wouldn't blindly follow this on FI.

After a bunch of testing (and posting, and thinking, and testing more, etc) I've finally settled on a throttle map I really like. I've done some drivability testing on this map, and more importantly I've done datalogging of several reasonable candidate maps with Cipher to add some numeric credibility to my subjective opinions.

Background:

The stock throttle map uses lower values at the upper end of the pedal range when at lower RPMs. This doesn't let you get on full power in the lower part of the range, instead opening up a bit gradually as the RPMs rise. This is sometimes perceived as throttle "lag" at low RPM. UpRev tuners have figured out that you can "fix" this by putting a solid line of slightly-over-maximum values (3800) in the uppermost column of the data, and then trying to smooth that into the existing factory data a bit for drivability. The idea is to give you a similar-looking throttle curve in the useful parts at all RPMs, which reaches the maximum.

However, "simple" or "naive" attempts to just set a few top columns fixed at 3800 and step off of that in linear amounts (which is what my tuner did. I don't fault him for that, it took hours of mathing around with curve fitting algorithms, plotting software, and testing to do better), you get a jerky throttle response map, and you can feel it places when driving.

My first attempt to smooth this out (while retaining the benefits) was a linear map from low-end stock values out to a couple columns of 3800, which was better, but still not ideal. I found that a simple 2nd order polynomial curve going through 3 target data points (stock 0% values, a fixed value at 50%, and 3800 at 100%) seemed to give better results, given some tuning on the middle fixed value. A reasonably magic value for the 50% mark seems to be 2300. The polynomials were derived using the perl module Algorithm::CurveFit from CPAN.

The Data:

In all of the charts below, the maps in use are:

Linear: This was my first smoothing attempt, the one that was posted here at the top originally. It's a straight shot from around 18.8% up to a couple columns of 3800's at the end.
Curve 2700: This is the good polynomial curve, but with the middle value set to 2700, as an example of what happens when it's a bit out of range.
Curve 2300: This is the good curve, with the middle value at 2300. You'll notice it tends to approximate the stock curves in Cipher data graphs, which is a really good sign.
Stock: This is the bone stock throttle map
Tuner: This is the simplistic "jam some 3800s into the top of the chart and roughly smooth down from there" approach that came from my tuner. I didn't datalog this for the data charts since I threw it out of the running long ago, but it's in the first chart just for comparison sake.

These charts were generated from the raw data using Plot.

This first graph is of the raw table data itself, just the line of values for the 4800 RPM row, to give you an idea of the shape and smoothness of each of the candidate maps. Note that axis labels are what they're called in the UpRev Rom Editor, but even UpRev acknowledges that we don't really know what these numbers really mean. "Flow Potential" seems to roughly correspond with the accelerator pedal position, and "Driving Force" has something to do with engine throttling via the butterflies and/or VVEL.

Note that "Curve 2300" makes a good smooth curve approximation of the Tuner values, and the "Curve 2700" is the same shape but roughly bumped up to enclose the Tuner values.

http://www.the370z.com/members/wstar...0-rpm-line.png

The next two charts are based on Cipher data logging of the first 4 candidate maps above. The log snapshot was taken with me rolling through the accelerator pedal from a low position to full throttle at a reasonable approximation of "linearly" in 3rd gear from around 3000 RPM to redline. Since I knew I wouldn't be able to reliably reproduce the same pedal curve for each run, the time-axis was thrown out and the data has been re-mapped strictly versus the accelerator position itself, to provide clean comparisons.

The first datalogging chart is Accel Pedal vs Throttle Position Sensor. The important takeaways here are that (1) the Linear map actually has a big non-linear bump in the real world versus the stock curve, (2) the 2700 curve does crazy things up top and doesn't even sustain full throttle, and (3) the 2300 curve does a good job approximating the stock response curve.

http://www.the370z.com/members/wstar...rottle-pos.png

The other is Accel Pedal vs "VVEL Position Sensor". Don't ask me what that means, but it's still interesting to observe diffs in the shapes. Note again the 2300 curve is the closest to stock, the 2700 curve is kinda screwy at the bottom, and the linear curve is a bit off at the top in the opposite direction. I take the stronger divergences away from the stock shape to mean the engine is telling me "you're doing it wrong" :)

http://www.the370z.com/members/wstar...s-vvel-pos.png

So I've settled on the 2300 Curve above. It seems to provide the best blend of (a) getting those 3800 values across all RPMs at the top of the pedal, so you're not limited by "throttle lag" at lower RPMs, (b) having a smooth graph shape with no sharp, unpredictable transitions, and (c) having smooth results that closely mirror stock in the important related Cipher datalogs during a smooth pull through 3rd gear.

The 2300 Curve Data:

You can copy this straight from here and paste it into a throttle table in UpRev:

The results should look like this in the editor when displaying decimal values:

http://www.the370z.com/members/wstar...-data-view.jpg

And this is the UpRev view of the whole map surface for it:

http://www.the370z.com/members/wstar...rface-plot.jpg

If you're concerned about compatibility between my stock ECU setup in general and yours, this is what my stock throttle map looks like for comparison:

http://www.the370z.com/members/wstar...rottle-map.png

I should add a request too: does anyone out there understand what the "Driving Force" vs "Flow Potential" axes really mean?

I don't at the moment but I'm getting my uprev tune on sunday and I'll ask the tuner for ya

I'll check this out tomorrow.

This is nice! I have the cable that came with the GTM turbo kit, but no software :-/

BTW, I created this thread below and wonder if you can chime in. I miss the quicker response of the DE/HR. I wonder if it's possible to compare the tables.

http://www.the370z.com/engine-drivet...hr-vs-vhr.html

Nice work! I'm taking my car in to uprev to get my maps fixed and retuned soon, so I might ask Jared to drop this table into one of my maps and test it out.

Awesome, thanks -- I will pass this on :tup:

"Driving Force" appears to = Load and "Flow Potential" is either VE or MAF counts (or a calculated perecentage based on both).

Load is based on RPM, VE, and g/sec of metered air, so that's probably about right.

Yeah the table still doesn't make intuitive sense to me though. The tuner I used (as in, the dyno-tuning professional) seemed to know what he was doing and set all "3800" values in the last few columns though, and that seems to correspond to WOT at full pedal.

It's clear from experimenting that this table does affect how the throttle reacts to pedal input, but both of the non-obvious labels seem like secondary effects. The position of the throttle butterfly will determine airflow, and that combined with RPM is pretty much going to define load or driving force or whatever. It just seems like one of these axes must be mislabeled for this to be a throttle table.

Very cool geeky stuff! luvit

Interesting stuff. Doesn't the VVEL vary the valve lift and duration to control power and the throttle butterfly stays wide open nearly all the time? If so, then the power varies more by VVEL rather than butterfly position.

I've heard that myth often, but I'm pretty sure that's not the case. VVEL very likely does vary the valve lift over different operating conditions, but that's no real substitute for actual throttle plates (which is why you still need ITBs even on the most advanced engines).

The easy way to tell is to log the throttle position over OBD-II, which is what I do on Torque while playing with this stuff. The basic Throttle Position PID comes back as angle data, and it ranges from around 1.0 to 89.6 in my testing so far. Generally speaking, if anything the throttle position has a tendency to stay more closed than you'd expect on stock-ish maps, and only opens up fully when you're at full throttle combined with high RPM.

Later today I plan to test some "extreme" maps that will get to the bottom of the mysteries of this table I think. I'm thinking one that ramps to 3800 after the first 4-5 columns or so, and one that never gets higher than about 1500 even at the end. Results should be "interesting", and will confirm whether the table is really just a pedal -> butterfly vs RPM map, or there's something more complicated going on.

Ok, so I did my crazy extreme map testing. I need to sit down and think through the results, but they should be informative.

Based on my smooth map from the top post, crazy map #1 was altered so that all of the columns from 37.5% flow onwards (to 100) were all pegged to the value "3800". The result from a driving perspective is that when I reached somewhere around 1/3 gas pedal position, the car would suddenly jump like I nailed the pedal to the floor, the OBD-II throttle position values would jump out to high values (wide open), but the whole jump would be very brief. Basically if I held onto that pedal position, the car would pulse on the throttle between 1/3 and full. It was like it was trying to take off at full throttle, but something else in the ECU held it back a short moment later.

Crazy map #2 was the opposite. From the 37.5% column onwards, all values were pegged to the number "1310". The reaction was somewhat similar. At around 1/3 throttle, the car would suddenly jump in power like I tried to nail the gas hard. However, the OBD-II throttle position sensor would *not* jump to wide open when this happened, just the engine power surged, and power got retarded back pretty quickly like the previous test, although smoother.

I imagine all the throttle jumping around and acting retarded in both scenarios is because there are other tables involved (e.g. VVEL) and the ECU in the overall is either confused by or just flat refuses to follow the contradictory commands with crazy values. But it does seem to confirm that raising the numbers in the table leads the ECU to at least try to open the throttle wider.

I need to think more on all of this to make sense of it though.

It's because VE and MAF counts should go up with higher TPS and RPM -- but, the load tables must also activate different cels in the VVEL maps, which is where all the actual throttling takes place. Finally, there are target AF maps that also correpsond to those load values.

Basically, no matter how you scale the tables, actual physical VE will not reach maximum levels unless RPM is approaching redline and throttle (as controlled by VVEL) is wide open.

If the values in the table don't corerespond well to physical reality you will most likely get herky jerky engine responsiveness as it tries to maintain whatever the target AF ratio is for the corresponding load cell.

Can you adjust timing or fuel on tip-in? That's a great way to improve throttle response!

Also -- do the values in the map correspond to injector duty cycle? I'm guessing that they do, although exactly what 3800 means isn't clear to me... uprev doesn't use intuitive cell values for a lot of the maps...

You know how the VHR ramps up pretty slow under 3k RPM compared to DE/HR? Does this mean it still has the capability to ramp up pretty quick? I just want to verify the lag or slowness is really in the software than physical or mechanical.

Yeah, basically. I just want to get a better understanding of what this "throttle" table really does, and what we can do with it in practice. Probably the answer is "not much without access to VVEL, except smoothing things out".

I'm not messing with the MAF table or timing or fueling, just leaving those where they were set on the dyno. Lacking a dyno and the know-how, I don't really trust myself to play with that stuff and not cause myself a big problem . At least, for now. :)

I'm not sure what the numbers mean tbh. They could just be a fictional scaling value, or the product of some other units that make more sense. The highest points on the stock table on my car are in the 3600's somewhere, and I got "3800" from the fact that my tuner filled in a few upper columns with that value when he tweaked my throttle table. In any case I'm pretty sure they're Nissan's values, not UpRev's. UpRev just relocates the factory tables to RAM so they can be map-switched.

I may have related my story above backwards by the way, it may have been the lower-value crazy table that caused the butterflies to try to open earlier, not the one full of 3800s, and I got confused about which map was which. I'll check again tomorrow.

Well, some of that is simply lack of low-end torque. Nothing will fix the engine being a bit slower under 3K if it just can't do any better against the physical load. That aside though, I'm sure everything else is in software. My throttle map experiments were kind of crazy. For a brief instant when it hit the crazy part of the table, the engine responded like it never does under normal mappings. I'm quite sure it's mechanically capable, but a lot of this stuff may require access to VVEL tables.

just to chime in here, most of the time the throttle plate is fully open, VVEL is controlling air flow and sending a simulated TPS signal back to the ecu. Charles at CJM (Phunk) confirmed this and had tuning issues using a return kit with a FPR. He basically said he had to disconnect the vacuum source as the cruising/off throttle vacuum was not correct/consistent since the throttle plates where not actually closing entirely.

Also, there still are no fuel tip-in maps as far as I know, but they are working on them.

That sucks. Once those can be accessed you should be able to really get great throttle response without screwing too much with the scaling of things.

Most ECU's pull timing on tip in (can be especially aggressive on autos), so if you add timing back in and a little extra fuel (sudden change will make AF ratios skew lean -- might not matter too much if Nissan did a good job tuning that) you can achieve instantaneous response and really smooth transitions from low to high load.

Does it feel like it has a light flywheel at some point? I'm still not entirely convinced it's lack of torque because even a Corolla has a sharper throttle tip in which can overwhelm the front tires (simply because I wasn't used to it). When I drove the '08 350Z, I barely tap the throttle and the revs rip to 2k in no time as if it has a lightened flywheel. I even broke loose the tires tapping the throttle in 1st. With our cars, it just has a progressive ramp to 3k as if it is in tire saver mode lol.

Ah! I hadn't considered the idea that the "Throttle Position" feedback coming over OBD-II was faked. In that case, it does explain a lot of my misunderstanding, and it also means that this "throttle map" is really more about some aspect of VVEL's operation rather than the butterflies. I'm almost tempted to put a bullet camera in my intake tubes so I can watch the real throttle and confirm it myself.

Anyways, I like my smoothed version to drive on still, even if it's just based on math and a total lack of understanding :)

Since we have 5 maps to switch from, are you able to put this table on one of the maps and retain the original table for say... winter driving?

Oh I see you have 7AT... I wonder what the tables for 6MT and 7AT are like.

BTW... since I only have the cable that came with the GTM kit, do I still have to buy the s/w separately to log and view this stuff? I didn't hear anything from UpRev.

Good question. If you have an UpRev cable, it probably has some sort of license attached to it, the question is which kind. If you go to UpRev - Engine Management, you can download their software there. Either Cipher or Osiris Standard (one of the two, probably Cipher) comes with a License tool that will tell you what your cable is licensed for.

The smoothed map isn't incompatible with winter, at least not on my car. It's just... smoother, while still reaching those 3800 values that my tuner seems to think allow easier WOT at all RPMs. The main thing I need to figure out now is whether I'm being robbed of raw acceleration in exchange for this smoothness because he's got the idea behind these table numbers totally backwards :)

I got some support via email from UpRev today on this. Basically they confirmed that setting the 3800 values up high is about what they normally do to get better WOT capability on Z/G cars in general. They also confirmed that nobody really knows how this table works, it's just trial and error. To quote from their Nissan tuning guide PDF:

Anyways, I'm going to continue trying out various refinements to how my table is set up, in case my current smooth map at the top of the thread can be improved.

Thanks! Got it. Everything's disabled except Cipher. It appears I am also able to flash the ECU, but not dump it.

It'll be nice to "open source" the throttle control project. Pretty soon flashing our cars is like Android flashing our phones. :)

It's probably a "Standard" license then. You can probably upgrade it to Tuner, but you should send them a License Report from that cable firmware tool first to be sure.

Unfortunately modding our ECU (or any car ECU really) is never quite as open a process as I'd like. I'm an open source developer myself, but the ECU world is all about trade secrets and warranties and whatever.

Nissan doesn't tell anyone how the ECU works. UpRev reverse engineers it to tease out whatever maps they can, but the deep details they produce (which allow them to make their roms and tools), they keep to themselves so they can run a profitable business, as it takes a lot of money to do the reverse engineering of this stuff.

I plan to continue posting whatever I can about whatever I can learn from playing with the tables in the Tuner edition of UpRev, but I don't think that will lead to anything resembling an open source ECU for our cars. Mostly it's just to reduce duplication of effort figuring **** out.

The quote from the Nissan tuning guide fits my earlier comment. Basically, you are balancing fuel, spark, actual measured air mass and theoretical VE derived from forumulas based on the known displacement of the engine, RPM, and thottle position (really, VVEL).

There's probably limits to how great those values can be before they are not doing a good job of modeling the physical reality of acutal air mass ingested at a given RPM and VVEL position(s).

Modeling airflow is a real PITA, and yeah, a lot of it is trial and error, especially if the values you can record/ adjust aren't intuitve.

I guess you can try datalogging VVEL and MAF g/sec (assuming you can get this data from either upRev or from an OBDII scan tool) and try to figure out more precisely what the range of values ought to be.

Actually -- let me recommend a really good text that may be helpful as you learn how to tune it --> Amazon.com: Engine Management: Advanced Tuning (9781932494426): Greg Banish: Books

I found that book to be incredibly valuable in figuring things out when I used to tune my previous car.

Oh yes... that thought completely slipped my mind. I guess being able to truly open up at 100% is a good start, but I don't know if mine is doing that until I start logging data with Cipher. That's the sense I get every once in awhile as if the throttle map changes in real-time, and it becomes less aggressive or limited as things heat up.

This link might be helpful -- older ECU, but I bet the newer ones operate under same general parameters. Also explains how to figure out the hexidecimal values and interpret them.

Turbo Upgrade for VG30DETT

Well, things always change on these cars as they heat up. It's not so much that they suck when hot, it's that they're highly self-optimizing when it's not hot, and they have to back off as conditions change to avoid knock.

I'll try to see if I can get a video of my current throttle responsiveness sometime in the next day or two, using my tuner's setup + my tweaks on the throttle map + the 7AT torque map. I guess maybe two runs from 3K to redline in 2nd gear, one where I roll into full throttle roughly in line with the revs, and one where I just stomp it open, and then ditto from down around 1.5K RPM? Maybe one full pedal run from a dead stop through 2 gears would be interesting too. I think it probably will break the back tires loose on that currently, even without trying to preload like a drag launch.

Does it make much of a difference if you rev in neutral?

Here's a video I made to test throttle response. Skip to 50 sec. Details are there as well:


Basically I try to floor it around 1.5-2k RPM in 1st and 2nd from a roll. "Cool" means running test immediately after engine properly warms up. "Hot" means after at least 15-30 min. drive on a warm day in which oil temps are in the 180-200F range. This is an old video in which my car only has an exhaust.

Here's the turbo video (before and after). Skip to 2:05 mark.


For the 3rd gear pull, I keep it steady around 2-3k RPM (~50 mph) and floor it to redline. This is probably my best pull regardless of engine oil temp, but it does make a difference.

The remaining runs are 1st thru 3rd from a roll (freeway entrance), so I try to start at low revs in 1st (1.5-2k RPM).

The goal is to be under 3k RPM (preferably 2k) because it seems like revving past 2.5k typically yields consistent "more poweful" pulls regardless of temps. In other words, starting at low revs result in slower runs. Starting at higher revs result in faster runs. [shrugs]

Digi totally off topic but are you gonna get different springs for the BOVs to take care of that compressor surge?

You have Turbosmart BOVs right? In some models the spring pressure is adjustable from the top, no need to replace spring.

http://www.the370z.com/members/digit...1-gtm-fmic.jpg

I think those are turbosmart BOVs but I don't see an adjustment bolt on the top. Yes, you would want to soften the spring just a little

Oops. I'm derailing this thread lol. We'll continue via pm.. Back on topic..throttle response..

Props for cooking up a solution:tup:

I know a lot of people will get some good use outta this.

Red: Keep in mind I'm still experimenting. I'm still running the one I pasted up top as my main map for now, but I'm using 3 other maps to continue to explore and tweak, there may be more revisions to this table coming depending on results.

DIGI: To be honest I don't know if I can compare or comment really on your vids, since you've got TT and I'm NA. There are just a whole lot of variables in play between us because of that. It would be interesting to have an UpRev tuner (or get the license upgrade yourself if that's possible on your cable) pull out what your current throttle map looks like though. I wonder if GTM leaves it stock, or if they had to change the values wildly for TT.

throttle response in N will be different -- motor is not under any real load.

Random notes from testing: the Throttle Position (as in butterfly) data in OBD-II may be faked, but it does track something roughly equivalent in VVEL if so. I did some logging on the curves while trying to roll through the throttle smoothly and consistently using different test maps. One was my standard smooth map to 3800, and the others were modified to smoothly reach 3200 and 4200. The funny thing is that in spite of the large change in the wide-open numbers, it was hard to detect any real difference in the graphs or the driving feel.

The 4200 map did tend to ramp out a bit quicker at the end (which just makes fine-grained control with the pedal more difficult), and the 3200 map did seem a little smoother at the top, but the differences were pretty trivial. It seems like the numeric maximums are largely irrelevant within reason. What causes throttle behavior changes is the shape of the curves (since they all started at the same low-end values, the 4200 map had a sharper slope than the 3200 map).

Also, based on testing, and based on reading some google search results of UpRev guys posting on other forums, reaching WOT at any RPM was never an issue on this car. Even on my stock throttle map, I can get the TPS output to peg when I stab the throttle from a stop in first gear. Apparently running a map like mine does remove some throttle latency in lower speeds/gears though.

What's left to test really is playing with the curvature. Right now I'm running linear (by percentage) from 18.8% to 96.9% on the table, and the TPS outputs still look fairly non-linear when rolling through the pedal smoothly. By that I mean, it goes relatively smooth for a while, but in the upper region it tends to just skyrocket relative to pedal position (i.e. more in the shape of an asymptotic graph), which I guess means I need to run the numbers up a little quicker near the bottom and flatten out the deltas in the upper-mid part. Going to try some other curves on the data and see what makes it smoother.

IIRC, Sam says he left the tables alone for safety reasons, so it's simply a tune. Therefore, throttle response is the same before and after the flash. The only difference is when boost kicks in, and it feels like an extra push.

What will probably mess things up for boost is when I'm pressing down on the pedal halfway, and the throttle ramps up slow enough boost won't even build up as if the physical throttles aren't opening up as much as expected.

I have this feeling there's no 1:1 correlation with the accelerator potentiometer position and actual throttle position (or VVEL response). One would think that 0-5V equates to a linear response in how a physical throttle would open up, right? There are times when 2.5V would feel like 50%, and other times 2.5V feels like 25% at the same engine speed. [shrugs]

I bet that'll throw a wrench in your throttle table(s) equation... :icon14: It'll be nice to figure out how the tables are related to each other.

[EDIT] IIRC, from the UpRev forums, they say they're making progress with VVEL control.