Something is wrong with my VE tuning but I don't know what, please help

[kenand1988]

I was able to get idle dialed in fairly quick after a few revisions and then I attempted to drive the car and there was horrible bucking and jerking. I could see the wideband going lean. The thing about is though that once you get through the bucking and jerking it smooths out and gets back to 1 lambda. I have the maf failed and I left ltft and stft on but I also have a wideband. I am seeing crazy VE numbers in some areas then normal in others. It can't possibly still be using the maf can it?

I will also say when in blend mode the car runs totally fine. I have tried using a back calc VE formula in the scanner and that do something but I wanted to give actual VE tuning a shot. I cant tell if this is a mechanical problem or something with the tune because it only happens under very light throttle.

2015 z06 m7
103mm tb
halltech intake
e38 fuel

[TriPinTaZ]

If you're still on the stock heads and cam, you're going down an unnecessary rabbit hole.

[kenand1988]

If you're still on the stock heads and cam, you're going down an unnecessary rabbit hole.

But whats the actual issue here?

[GHuggins]

A lot of the earlier lt4's wouldn't let you fail the MAF to log. It's probably not building boost or something like that causing you to pull a lot of fuel. I've even seen them jack rail pressure through the roof trying to fail the MAF.

[cadillactech]

What is your process for calibrating the VVE table? Using filters?

I plugged in your data into my graphs and it shows it massively lean at 1000 RPM.

Another thing, your engine torque at idle is negative. It should be 15 to 20lbft. Timing should be in the teens. Otherwise you have no control over idle speed using spark.

103mm TB scalar is usually 7200 or so but sometimes you have to play with it depending on who made it.

And I agree with Taz, you should calibrate for your modifications. You really have not alerted the engines volumetric efficiency so there is no need to change it from stock values.

[kenand1988]

I mean im on the throttle light as a feather and its this transition from 5% to about 12% throttle thats having the nasty bucking. I added more and more fuel and it made not difference. The maf status is failed and the cel is set. Not saying you're wrong but I don't think its a no boost issue. I experienced that before too. The instant boost started the throttle would shut. I'm just trying to dial in cruising and light take off. Ever since the throttle body there has been some surging around 25% throttle the tps jumps around 25% +- 2% and its noticeable. My thought was I need to get VE and MAF perfect then tackle VT.

[kenand1988]

What is your process for calibrating the VVE table? Using filters?

I plugged in your data into my graphs and it shows it massively lean at 1000 RPM.

Another thing, your engine torque at idle is negative. It should be 15 to 20lbft. Timing should be in the teens. Otherwise you have no control over idle speed using spark.

103mm TB scalar is usually 7200 or so but sometimes you have to play with it depending on who made it.

And I agree with Taz, you should calibrate for your modifications. You really have not alerted the engines volumetric efficiency so there is no need to change it from stock values.

It's massively lean but do you see in the VVE that it should be extremely rich? I added over 20% of fuel in that area 2x and it made no difference. The scalar number I got from the maker of the throttle body (Granatelli).

I set up 2 histograms for VE one with eq error and the other with ltft+stft. Log then paste special either the full change or half depending on how big the changes are.

The timing at idle needs work because of the throttle body. I made some changes to VT because before on stock VT timing was around 0 degrees. I reduced VT in idle areas to bring up the spark. It needs more work and I'm trying to tackle getting fueling perfect before attempting the VT again.

[kenand1988]

I think I will just start over from stock. The VVE table is so jacked up it's probably the crazy bad transitions that are messing with it.

[TriPinTaZ]

But whats the actual issue here?

If I had to guess, you likely altered the VVE table enough to jack up the torque model. Which my point was, with your mods, this is unnecessary.

[Alvin]

I agree with everyone.. VVE wasn't really needed. If you tried to back out VVE from MAF that could be the cause. Just somewhere you took a wrong turn with it.

If you didn't take in account for the cam advance the VVE results would have been bad.

[cadillactech]

I think I will just start over from stock. The VVE table is so jacked up it's probably the crazy bad transitions that are messing with it.

Yes, just load the stock file, adjust your throttle area, I would try 7200 and see if that helps with the idle.

Many ways to get the VVE off but steady state data is needed.

[TriPinTaZ]

I run stock or near stock Throttle Scalar values for 103mm and 107mm Throttle Bodies, if that helps you any. This applies to Katech, Nick Williams and Soler stuff. My logic may be different than others though so I'm not saying I'm correct. I just use airmass/VVE/torque calcs to make them behave. Sometimes if you change the scalar too much you start getting weird and crazy behaviors. The Scaler isn't actually a true value in the ECU, but more part of a slope equation that references airflow per blade angle. There are more tables that are not available to us as HPTuners stopped looking up tables and moved on to other things. I forgot the name of the calibrator that gave this discussion, but it was a well known and respected trainer. So I can't take credit for the knowledge. But it following their recommendation has served me well.

[GHuggins]

I run stock or near stock Throttle Scalar values for 103mm and 107mm Throttle Bodies, if that helps you any. This applies to Katech, Nick Williams and Soler stuff. My logic may be different than others though so I'm not saying I'm correct. I just use airmass/VVE/torque calcs to make them behave. Sometimes if you change the scalar too much you start getting weird and crazy behaviors. The Scaler isn't actually a true value in the ECU, but more part of a slope equation that references airflow per blade angle. There are more tables that are not available to us as HPTuners stopped looking up tables and moved on to other things. I forgot the name of the calibrator that gave this discussion, but it was a well known and respected trainer. So I can't take credit for the knowledge. But it following their recommendation has served me well.

Jason, could this possibly cause the throttle to just over open on it's own? Technically a lt4 and l86 TB should be close but if I need those other slope tables then that would explain a little. I haven't had any issues on the lt4 or factory blown cars but trucks are a different story. Factory blown seem to reference the dd as a limiter only whereas trucks mostly have to have the dd table's spot on to work with boost. NA cars seem to be a completely different story and easy to dial boost in on too. Just trucks. Guess cause they're heavy. Anyway just wondering what all is in the cal for throttle control or if you happen to know the thread where it was discussed.

[cadillactech]

Jason, could this possibly cause the throttle to just over open on it's own? Technically a lt4 and l86 TB should be close but if I need those other slope tables then that would explain a little. I haven't had any issues on the lt4 or factory blown cars but trucks are a different story. Factory blown seem to reference the dd as a limiter only whereas trucks mostly have to have the dd table's spot on to work with boost. NA cars seem to be a completely different story and easy to dial boost in on too. Just trucks. Guess cause they're heavy. Anyway just wondering what all is in the cal for throttle control or if you happen to know the thread where it was discussed.

I remember Howard from Redline mentioned a while back that when NW had the 103 come out for the LT's he said it didn't need a scalar update and Howard questioned it but Nick said the low throttle plate angle area flowed the same as stock and it did not skew the throttle flow curve past what was in the ECU.

[GHuggins]

I remember Howard from Redline mentioned a while back that when NW had the 103 come out for the LT's he said it didn't need a scalar update and Howard questioned it but Nick said the low throttle plate angle area flowed the same as stock and it did not skew the throttle flow curve past what was in the ECU.

I remember that thread. Think it was years ago when that was discussed but I also know Nick designed "that particular" tb just so it wouldn't require any changes much. It was purposely designed to flow the same air as stock to a certain opening. I still find it needs slight adjustments of the scaler to not be jumpy, but guess you could address that in the tm all the same like Jason mentions.

[JLawson240]

What is your process for calibrating the VVE table? Using filters?

I plugged in your data into my graphs and it shows it massively lean at 1000 RPM.

Another thing, your engine torque at idle is negative. It should be 15 to 20lbft. Timing should be in the teens. Otherwise you have no control over idle speed using spark.

103mm TB scalar is usually 7200 or so but sometimes you have to play with it depending on who made it.

And I agree with Taz, you should calibrate for your modifications. You really have not alerted the engines volumetric efficiency so there is no need to change it from stock values.

Cadillactech do you mind elaborating a bit on some of the filters you recommend for VVE tuning. I've seen you mention that on more than one occasion. I'm relatively new to tuning, haven't touched a Gen 5 yet, and scroll the forums looking for the "Real ones" that I can tell know what they are talking about. Then I go thru and read most of what you guys post and your responses to others to learn. Anywho, there are a few of you guys on here that clearly understand what you're doing (GHuggins, Alvin, Squirrel, Ben Charles, etc) and I'd truly value any input you're willing to share. Thanks!

PS- Don't mean to hijack the thread, if there's a better way to go about this please advise

[TriPinTaZ]

Jason, could this possibly cause the throttle to just over open on it's own? Technically a lt4 and l86 TB should be close but if I need those other slope tables then that would explain a little. I haven't had any issues on the lt4 or factory blown cars but trucks are a different story. Factory blown seem to reference the dd as a limiter only whereas trucks mostly have to have the dd table's spot on to work with boost. NA cars seem to be a completely different story and easy to dial boost in on too. Just trucks. Guess cause they're heavy. Anyway just wondering what all is in the cal for throttle control or if you happen to know the thread where it was discussed.

Yes it can but I have found that bumping up the airmass in the lower MAF region along with a minor VT adjustment seems to work best for me in regards to ZL1 and Z06 stuff. Then on some cars I do adjust the scalar up or down to fine tune it a bit but usually I don't change it by more than a value of 500. There are some VT changes that I make as well for throttle lift after WOT. I've had a couple of Automatic Transmission cars the didn't want decelerate quickly enough. The throttle sort of closes a bit too slow, DFCO doesn't kick in quickly enough and makes the car want to push through the brakes for a second or two until the ECU pulls the torque down. I don't actually know if this is directly related to the TB or just the extra blower speed or maybe both. Not every car has this issue. But either way, Virtual Torque adjustments bring this back in line. There are also some DFCO tables that can be massaged if its not going into DFCO fast enough.

Another thing I do is change the MAF curve to have a spike(more like a hump) in it to reflect all the extra airflow once the throttle blade opens up past 30%. I primarily tune C7's, CTSv's and Gen 6 Camaros(ZL1 and SS) and this is what I've learned over the years to make things behave. We street test all of our tunes for drive-ability and there was quite a bit of learning to get these to drive really nice. It also helps that my business partner and I both have the same kind of cars we tune/build and with the same or similar mods that we use in builds and we are both very nit picky about street manors.

As for the truck stuff, I have messed with a handful of trucks, but they seem to have some nuances that differ from the LT1/LT4 stuff. There was one truck I couldn't make behave no matter what. It was a remote tune and I finally had to advise the client either I can't get this done or you have a mechanical issue. My point here is that I can't say with confidence my methods work on the truck stuff the same as they would on the Gen V stuff I usually tune. Anyhow, if you'd like to see one of my files for the LT4 that references some of these topics, shoot me an email.

[cadillactech]

Cadillactech do you mind elaborating a bit on some of the filters you recommend for VVE tuning. I've seen you mention that on more than one occasion. I'm relatively new to tuning, haven't touched a Gen 5 yet, and scroll the forums looking for the "Real ones" that I can tell know what they are talking about. Then I go thru and read most of what you guys post and your responses to others to learn. Anywho, there are a few of you guys on here that clearly understand what you're doing (GHuggins, Alvin, Squirrel, Ben Charles, etc) and I'd truly value any input you're willing to share. Thanks!

PS- Don't mean to hijack the thread, if there's a better way to go about this please advise

You want to filter out any transient throttle conditions as these will be rich/lean spikes that will skew everything. Also you want to filter out data during transmission shifts, certain fuel trim cells, etc. This is helpful if you are gathering data out while driving on the street but in a perfect world you would throw it on your load bearing chassis dyno, put it in open loop and step through each VVE cell until you had a 1-2% error and call it good.

There is a lot of good information for creating filters in the Gen4 forum and elsewhere on the site. Everyone has their own way of doing it but you are going for the same end goal, steady state data without error from throttle changes, transmission shifts etc.

[GHuggins]

I noticed in the zr1 factory files that the OE really nose dives torque right at the end to do the same thing - clsoe throttle and shift the trans, so don't think you're doing anything wrong there.

This is a factory zr1 file if you need one. I got this from Dave, so I know it should be factory with the 2650 blower and 95mm tb. I've got my coding person pulling some of the code apart looking for the other throttle controls. I'm hoping there are some pressure ratio tables for throttle, but will see. She said there was an opening rate table - which I assume is the linear table discussed earlier.

I'll shoot you an email for the other. Thank You

[kenand1988]

As an update, I figured out a few things. VE is now good. My first wrong step was using manifold switch closed table and not the open table. I have modified the VE as much as I can in purely SD mode because I can't get into any boost. I noticed there is no partial throttle surge when in SD but there is when in blended and in purely MAF mode. I am trying to get the MAF better dialed in because it would seem to me that's the culprit. I was able to get Idle spark to around 20 degrees although this was done by lowering VT a few times which means I have a negative value for tq at idle. I think this is why the previous ghost cam tune I was using is not working anymore. For those wondering if I leave VT alone my tq is about 15-20ft lbs and timing at idle is -3-0.