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Negative Mid LTFT and more issues!

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Old Feb 1, 2017, 01:53 PM   #31
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Originally Posted by Biggiesacks View Post
I have never tuned SD on an evo but I know that SD is way more sensitive to tuning then MAF so getting a second opinion on the tune itself would also be high on my list, and after swapping the cams you probably need an actual retune and not just some adjustments not based on actual logging. I believe you said your tuner just sent you a rom that was suppose to adjust for the stock cams, but im assuming that it wasnt adjusted based on an actual tuning session?
It was tuned remotely via me sending him data logs and then him sending a modified rom. We did that only 4 times. It never ran right after the swap and my tuner is very hard to get a hold of so I kind of gave up and decided to fix all this myself.
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Old Feb 1, 2017, 02:02 PM   #32
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With the stock ECU tuning SD is definitely more advanced. There is alot more nuance to it and less easy to find information about the tricks tuners use to get it running well. If i was you, I would go back to a MAF. The thing with SD is you will be even more hard pressed to find anything "generic" to start from. The suggested way to transition to SD is to tune the car with a MAF then switch over to SD and adjust the maps from there. It also really depends on your goals, most people will transition to SD usually because of their power goals. Its hard to use a MAF on a forward facing turbo setup for example. For me, i would prefer a MAF unless it simply doesn't align with my goals.
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Old Feb 1, 2017, 05:35 PM   #33
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Can someone tell me if these settings would be ideal / recommended for my stock injectors with walbro fuel pump setup? As an aside, these happened to be the same injector battery voltage latency compensation figures the tuner used on the original tune which consisted of a top mount 6266 turbo with huge injectors making roughly 600whp. Shouldn't those have been changed when I got retuned on my current setup with stock injectors (even including the Walbro)? If not, please excuse my newbish questions. If anyone didn't read the whole thread my setup is in the first post.

Injector Scaling: 504

Injector Battery Voltage Latency Compensation:

4.69 3.312
7.03 1.680
9.38 1.032
11.72 0.672
14.06 0.432
16.41 0.264
18.68 0.144

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Old Feb 1, 2017, 05:56 PM   #34
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I cracked open a stock IX rom and the Latencies look right, the scaling is 513 stock (not a big difference maybe just a small variance in stock ROM ID's). You are correct in assuming that larger injectors should need different scaling/latency numbers, so im not sure what thats about.
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Old Feb 1, 2017, 05:58 PM   #35
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I cracked open a stock IX rom and the Latencies look right, the scaling is 513 stock (not a big difference maybe just a small variance in stock ROM ID's). You are correct in assuming that larger injectors should need different scaling/latency numbers, so im not sure what thats about.
Biggie,

Am I crazy or does this thread indicate the latencies to be very different?
https://www.evolutionm.net/forums/ec...r-latency.html

Let me know your thoughts.

EDIT: Nevermind, I see that those figures are just for the opening time of stock injectors not the total latency compensation numbers. Well, I was really hoping that those numbers were off as that would have explained why I was running so rich on stock injectors. Back to the drawing board.

Last edited by RelentlessEVO; Feb 1, 2017 at 06:11 PM.
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Old Feb 1, 2017, 06:06 PM   #36
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sorry your link doesn't have post count, but if you look on page 2 MRFred retested the stock injectors under pressure, simulating the stock fuel pressure, and got values really close to the stock values. I would guess the numbers are close enough that simple differences like the resistances introduced by the stock wiring harness and grounding could account for it.

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Old Feb 2, 2017, 04:42 PM   #37
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Biggie / anyone who is interested,

I checked the latest rom from my tuner and I'm totally lost. They increased the RPM VE table by roughly 15% points from 500 RPMs up to 4000 RPMs compared to the rom from tune with the S3 cams. They also increased my injector scaling from a previous 472 to 504. From my simple understanding wouldn't that dramatically increase the amount of fuel being delivered? As a side note, there was absolutely no change to the MAP VE table.
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Old Feb 2, 2017, 06:10 PM   #38
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From what I understand increasing VE would increase the amount of fuel delivered. As for the scaling, going from 472 to 504 would reduce the amount of fuel, but only by a very small amount as thats not a very big difference in scaling. Basically the ECU thinks the injectors are bigger so they don't need to be open as long to meet fueling demands. I can't say I understand the strategy your tuner was going for with those changes, but it does sound like you didn't get a legit re-tune.
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Old Feb 5, 2017, 07:20 AM   #39
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Well, I've already started tuning the Evo on my own. So far, I've managed to get my LTFT to -3.7% and my mid to -9.2%. But I have a couple of questions. I've read this thread many many times: https://www.evolutionm.net/forums/ec...ched-roms.html.

But I specifically have a question regarding the relationship between the RPM VE the MAP VE tables. The RPM VE table makes perfect sense. That table basically is an estimate of how much air is moving through the engine at a particular RPM point. Hence, when you reduce the VE % in the table you are basically telling the ECU that less air is moving through the motor and therefore the motor needs less fuel and vice versa when you increase the VE % you are increasing the amount of estimated air which in turn increases the amount fuel into the motor.

The MAP VE table has kPa on one axis and Load % on the other. I don't understand how it correlates or interacts with the RPM VE table. Is it simply VE correlated to a MAP (manifold absolute pressure) reading? Does it modify the RPM VE values?

Scheides said in his thread that "There are two tables that will get a lot of your attention: SD MAP Sensor VE and SD RPM VE. These tables correlate pressure and speed with engine load (and thus fuel), and should be started at a 1:1 ratio like so:" I don't understand what he means starting with a 1:1 ratio and the picture in his original thread is no longer visible. Can someone explain to me what he meant by a 1:1 ratio and how the MAP VE table effects the airflow calculation?

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Old Feb 5, 2017, 07:28 AM   #40
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Quote:
Originally Posted by Biggiesacks View Post
From what I understand increasing VE would increase the amount of fuel delivered. As for the scaling, going from 472 to 504 would reduce the amount of fuel, but only by a very small amount as thats not a very big difference in scaling. Basically the ECU thinks the injectors are bigger so they don't need to be open as long to meet fueling demands. I can't say I understand the strategy your tuner was going for with those changes, but it does sound like you didn't get a legit re-tune.
Biggie,

I, unfortunately, have to agree with you. From my very limited vantage point, it appears that my tuner spent very little time on my "re-tune." In fact, I am beginning to think he started with the incorrect rom which led to him dramatically increasing the RPM VE table (which would of course lead me to running very (dangerously?) rich). I cannot find another explanation on why he would send me a re-tune for going to stock cams from the GSC S3's with the RPM VE table figures being increased so much. To me it absolutely makes no sense. Every time I sent him a log he would respond with confusion and state that there was no way I was running stock injectors because the car was so rich. Point in fact, I was running so rich because of his tune. As I stated above, I have already leaned out the AFR's with a simple adjustment of my RPM VE table. I basically made it just a little leaner than it was on my original tune on the S3's.

I still have a lot of questions but you were dead on saying that it is a very rewarding process to tune my own car. I'm going to attempt to tune it on SD but I may end up having to go to a MAF setup and then later switch back to SD. Only time will tell.
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Old Feb 5, 2017, 10:57 AM   #41
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Biggie,

I, unfortunately, have to agree with you. From my very limited vantage point, it appears that my tuner spent very little time on my "re-tune." In fact, I am beginning to think he started with the incorrect rom which led to him dramatically increasing the RPM VE table (which would of course lead me to running very (dangerously?) rich). I cannot find another explanation on why he would send me a re-tune for going to stock cams from the GSC S3's with the RPM VE table figures being increased so much. To me it absolutely makes no sense. Every time I sent him a log he would respond with confusion and state that there was no way I was running stock injectors because the car was so rich. Point in fact, I was running so rich because of his tune. As I stated above, I have already leaned out the AFR's with a simple adjustment of my RPM VE table. I basically made it just a little leaner than it was on my original tune on the S3's.

I still have a lot of questions but you were dead on saying that it is a very rewarding process to tune my own car. I'm going to attempt to tune it on SD but I may end up having to go to a MAF setup and then later switch back to SD. Only time will tell.

I'm glad to hear your enjoying it. This is pretty much why i STRONGLY believe, if you want something done right, you gotta do it yourself.

So I believe the theory behind the two different tables as it relates to how SD works is this(please if someone else has a better/correct answer please chime in):

The engine is basically a big air pump with a fixed amount of displacement 2.0L etc. The perfect air pump would be able to completely fill the cylinder with air at atmospheric pressure at all engine speeds. Since you have a known displacement in theory you could calculate exactly how much fuel you would need to add to that volume of air to get your desired Air to fuel ratio. Unfortunately engines are not perfect pumps and because of head design, cam profile, intake manifold design etc the engine will have different volumetric efficiency at different engine speeds (RPM's). Through some clever techniques its even possible to get an NA motor to be more than 100% efficient at certain RPM's. So the RPM VE table is like a baseline of how good of a pump the engine is at a given RPM. Then there are also other factors, which is throttle and also in our case forced induction. This is where the MAP and temp sensor come in to help calculate how much of that air is being restricted, or forced into the engine. So say your engine is 100% efficient at 3000rpm but you are pulling vacuum and are at 7.25 psi (1/2 bar, or half of atmospheric pressure) measured on the MAP, theoretically you would be filling that cylinder half way full and thus would use half the fuel then if you where at 14.5 psi (1 bar or atmospheric pressure). In the previous example I just used im referencing from absolute 0, most people would calibrate their MAP reading to show 0 psi at 1 bar and negative numbers during vacuum. The reason MAF is easier is because instead of all this calculating, the computer can actually just measure the volume of air the engine is sucking in directly instead of having to try and make an educated guess based on all these efficiency tables.

I know this information doesn't really tell you how to go about tuning these two tables, having never done it myself on an evo, I don't know how the algorithms related to how load is finally calculated uses these two tables, plus others, to come to a final calculation, but i figured if i laid out the theory as I understand it, it might help you to figure out how to approach these two tables.

Last edited by Biggiesacks; Feb 5, 2017 at 11:27 AM.
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Old Feb 27, 2017, 07:57 AM   #42
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Update time!

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Originally Posted by Biggiesacks View Post
I'm glad to hear your enjoying it. This is pretty much why i STRONGLY believe, if you want something done right, you gotta do it yourself.
biggie,

I switched to a stock MAF setup a few days ago and guess what? You were absolutely right, all of my issues, running rich and even the cold start bogging/stuttering/stalling were because of my "tune." The ONLY change I made was to install an OEM MAF and flash a Tephra v7 rom. I had to change some settings to reflect the Omni map sensor and I zeroed out the BEC table but otherwise it's a stock rom. I couldn't get the car started at first even after copying the immobilizer information from my previous tune. Turns out that it was simply disabled by my tuner and he never told me. So I had to disable it in my new one and it cranked over first try.

I've done several cold starts and while it runs a little rich it does not bog, stutter, or stall. It runs very smoothly. I've also started tuning it myself and the MAF setup is much simpler. I don't think this setup will make as much power but I can always go SD after I get myself setup on the MAF.

So, in summation: both my S3 and stock cam tunes suffered from the cold start issues and my re-tune was so completely off that I was running VERY rich causing my fuel trims to be pegged full rich. My tuner's response was to state that my car couldn't be running stock injectors and then after sending me several poor tunes was to stop responding all together. This was of course after taking my $100 for my "re-tune." Oh, and as Raceghost and others have mentioned I did NOT need to remove my S3's and do a complete timing belt job as all of my issues were tune related. Talk about screwed. Sucks.

At least it's made me begin to learn how to tune my car myself. Can't believe this guy is a prominent, seemingly well-respected, tuner on these forums.

BIG thank you to Biggiesacks and to everyone else who has responded to this thread!
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Old Feb 27, 2017, 08:28 AM   #43
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Thats great news Relentless! I bet it felt good getting it running with that new tune, and I hope you enjoy getting it dialed in! Then of course getting to actually drive it at its potential.

cheers
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