Fuel trim cell stuck at 13 during WOT?? Wont go to 22? Confused?

[Torque_Vector]

I have been tuning VE to get it dialed in. When I log in closed loop the Fuel Trim Cell parameter gets stuck in 13 even when according to the data being logged should be in 15 or 22 during WOT 100% TPS.

I am confused what's going on? see attached log and tune.

2nd pass_1158.hpl - Log
E36 2002 Taho Flex 2Bar_ID1300_SD_VE CL Driving_VE24.hpt - Tune

[Lakegoat]

I am not sure what you are asking---STFT's are off during WOT. Wideband is used.
I see about 37 degrees spark at WOT in some places. That's a bit much

[Torque_Vector]

I am not sure what you are asking---STFT's are off during WOT. Wideband is used.
I see about 37 degrees spark at WOT in some places. That's a bit much

In the attached snip it. I highlighted the FTC parameter in yellow, according to the area of the VE table you are currently in ( 5600 RPM @ 100KPA MAP) in this should read accordingly to the FTC value so according to the VCM scanner help document and other sources this should be logging FTC = 15 or 22 at WOT not 13. See other snip it of the help file. When I flash a SD OL tune and log the FTC reads 22 at WOT. I am just confused thinking the the FTC parameter should be reading differently than what's being logged.

FuelTrimCell.PNG

help file ftc.jpg


As for the timing, yea I just switched to new OS 411 p01 and installed a Flex fuel sensor running pump E85 and I left the stock flex fuel spark table from the Tahoe which is saying its adding 16* in the table up top, so I was thinking I should just multiply that entire spark table by .5 so it would be 8* instead of 16. I was tuned on 93 with about 23* spark advance. So if I halved flex spark table I should be around 28*.

[Lakegoat]

This is not a smartass question---Why do you care what ftc it is in at any given time? I don't see how that is going to help you tune it. I turn off LTFT's to tune, permanently. I use STFT's for closed loop tuning.
If you are running SD, Dynamic air disable needs to be set to something like 8000 rpm.

[Torque_Vector]

This is not a smartass question---Why do you care what it is in at any given time? I don't see how that is going to help you tune it. I turn off LTFT's to tune, permanently. I use STFT's for closed loop tuning.
If you are running SD, Dynamic air disable needs to be set to something like 8000 rpm.

I usually use the FTC in the filters so that I can filter out all the idle, deceleration, etc.. data. For example I would only want data that is in FTC=22 or 15(all other data I want to be ignored). I have used it like this before in the past and it works(see attached old tune/log before I switched over OS) then it would filter out the data. It is in SD, I when I am tuning part throttle or all ranges for that matter I setup a tune map that forces it in open loop for this, but in this case I was in Closed Loop and was trying to use the FTC to filter all the data in closed loop so it would only give me data while at WOT and in Power Enrichment. I just have used it liked this before and know for some reason it seems like its not logging correctly. Everything seems to be running fine as I went and made my fastest pass so far 11.58 @ 124.7MPH. I gained almost 3MPH on my trap speed after switching to E85, ID1300 injectors and switched to the Flex fuel OS.

Look at the attached old Log/tune screen shot below. It shows the correct FTC 22 at WOT. This was before I switched over to the new OS and was not converted over to Flex Fuel. So for some reason something doesn't seem to be correct to me.

the only thing I can think of which i might try is logging the fuel trim Learn parameter. Maybe its because I haven't given the Fuel Trims long enough to do a full learn cycle and that could be why?

run2-5-2-21.hpl

dyno tune original_copy.hpt

Old_FTC22.PNG

[kevin87turbot]

I usually use the FTC in the filters so that I can filter out all the idle, deceleration, etc.. data. For example I would only want data that is in FTC=22 or 15(all other data I want to be ignored). I have used it like this before in the past and it works(see attached old tune/log before I switched over OS) then it would filter out the data. It is in SD, I when I am tuning part throttle or all ranges for that matter I setup a tune map that forces it in open loop for this, but in this case I was in Closed Loop and was trying to use the FTC to filter all the data in closed loop so it would only give me data while at WOT and in Power Enrichment. I just have used it liked this before and know for some reason it seems like its not logging correctly. Everything seems to be running fine as I went and made my fastest pass so far 11.58 @ 124.7MPH. I gained almost 3MPH on my trap speed after switching to E85, ID1300 injectors and switched to the Flex fuel OS.

Look at the attached old Log/tune screen shot below. It shows the correct FTC 22 at WOT. This was before I switched over to the new OS and was not converted over to Flex Fuel. So for some reason something doesn't seem to be correct to me.

the only thing I can think of which i might try is logging the fuel trim Learn parameter. Maybe its because I haven't given the Fuel Trims long enough to do a full learn cycle and that could be why?

run2-5-2-21.hpl

dyno tune original_copy.hpt

Old_FTC22.PNG

That's a lot of spark advance for a 11.25:1 compression engine. Have you ever made a pass with a little more reasonable amount of timing? Maybe around 31-32 degrees max?

[Torque_Vector]

That's a lot of spark advance for a 11.25:1 compression engine. Have you ever made a pass with a little more reasonable amount of timing? Maybe around 31-32 degrees max?

If you look at run2-5-2-21.hpl log that was before I converted to flex fuel, smaller injectors, and was running 93 octane. It was at 23 degrees up top. The fastest run with that setup was 12.02 @ 120.29 and the fastest trap speed I ever got was 122 with that setup. I haven't tried making a pass with 31-32 degrees.

I then switched to the new OS and I copied over my tune and I didn't change the timing. All I did was leave the stock Flex Fuel Spark table with what it was prepopulated with stock and that is why I think it is so much advance, because if you look in the screen shot below its adding 16 degrees with E85. so 23+16=39-3(IAT spark)= 36 total (is this correct?)
(bottom left table that is partially hidden is the IAT advance spark correction)
spark tables.PNG


I am still learning and haven't really played with timing adjustments as I had the car dyno tuned so I have just left the timing from that and only have been adjusting the VE table, idle, fuel injector tables, transients etc... I am afraid to do any timing adjustments without a dyno. But it sounds like I need to back off the flex fuel spark timing table so my total timing is around 31-32 at WOT? What RPM and Map range are you talking for the 31-32? And are you talking with 93 octane or on E85?

[kevin87turbot]

I would start by backing off of the flex fuel spark table until you have it only adding 5 degrees more than your pump gas calibration. It'll be safer than what you're currently running, and will be close to optimum for your application. Typically around 28-29 degrees total timing at WOT would be a good starting point on E85. If you were on 93 octane, 23 degrees is going to be really close to being perfect on your application.

If you look at the original flex fuel spark tables, you need to consider that those values were added to the stock timing tables. If you pick a value in the main spark table...let's say 5200 rpm and .68 Cyl Airmass, it's 16 degrees timing. Now, just look at the corresponding additive value in the flex fuel table, it's 13.1 degrees. At that point, it'll be 29.1 degrees on E. That's a very good starting point at that particular load and rpm.

When you go to the dyno or the track, you can try adding another degree or two and see if it likes it or not.

[Torque_Vector]

I would start by backing off of the flex fuel spark table until you have it only adding 5 degrees more than your pump gas calibration. It'll be safer than what you're currently running, and will be close to optimum for your application. Typically around 28-29 degrees total timing at WOT would be a good starting point on E85. If you were on 93 octane, 23 degrees is going to be really close to being perfect on your application.

If you look at the original flex fuel spark tables, you need to consider that those values were added to the stock timing tables. If you pick a value in the main spark table...let's say 5200 rpm and .68 Cyl Airmass, it's 16 degrees timing. Now, just look at the corresponding additive value in the flex fuel table, it's 13.1 degrees. At that point, it'll be 29.1 degrees on E. That's a very good starting point at that particular load and rpm.

When you go to the dyno or the track, you can try adding another degree or two and see if it likes it or not.

Thank you for your help! I was going to try and use acceleration rate I'm logging from the speed sensor/maths and compare specific MAP vs RPM areas and see if the rate of change goes up or down after changing the timing. If I compare my runs before and after flex fuel you can see that the acceleration rate is higher with the E85 with the excessive timing in the , but its not a good enough comparison as I have limited WOT data on the 93 octane log so I will try and test this out. Do you think it should work?

acceleration rate.PNG

By changing the timing do you need to retune/adjust your VE table again every time you make a change?

[kevin87turbot]

Thank you for your help! I was going to try and use acceleration rate I'm logging from the speed sensor/maths and compare specific MAP vs RPM areas and see if the rate of change goes up or down after changing the timing. If I compare my runs before and after flex fuel you can see that the acceleration rate is higher with the E85 with the excessive timing in the , but its not a good enough comparison as I have limited WOT data on the 93 octane log so I will try and test this out. Do you think it should work?

acceleration rate.PNG

By changing the timing do you need to retune/adjust your VE table again every time you make a change?

It will affect the fuel table, but only slightly. 1 or 2 degrees only has a small impact on fueling at your level.

I like your plan to measure the rate of acceleration. It's a valid method. I did the same thing before I got a Dragy.

[eXo3901]

In the attached snip it. I highlighted the FTC parameter in yellow, according to the area of the VE table you are currently in ( 5600 RPM @ 100KPA MAP) in this should read accordingly to the FTC value so according to the VCM scanner help document and other sources this should be logging FTC = 15 or 22 at WOT not 13. See other snip it of the help file. When I flash a SD OL tune and log the FTC reads 22 at WOT. I am just confused thinking the the FTC parameter should be reading differently than what's being logged.

FuelTrimCell.PNG

help file ftc.jpg


As for the timing, yea I just switched to new OS 411 p01 and installed a Flex fuel sensor running pump E85 and I left the stock flex fuel spark table from the Tahoe which is saying its adding 16* in the table up top, so I was thinking I should just multiply that entire spark table by .5 so it would be 8* instead of 16. I was tuned on 93 with about 23* spark advance. So if I halved flex spark table I should be around 28*.

12500 - Long Term Fuel Trim RPM Boundaries
or
12171 - Dynamic Airflow Zone - RPM Boundaries
or
12172 - Dynamic Airflow Zone - MAP Boundaries

It looks like some boundaries were changed at some point in those tables. One of those tables might get your FTC back to what you expected.

[Torque_Vector]

It will affect the fuel table, but only slightly. 1 or 2 degrees only has a small impact on fueling at your level.

I like your plan to measure the rate of acceleration. It's a valid method. I did the same thing before I got a Dragy.

If I adjust the entire flex fuel spark table in half, assuming I am running full E85 which is reducing spark adder from 16* to 8* in the WOT areas, I figured that would be enough to change the VE table significantly? I also was wondering if you could just adjust the fueling of the entire VE table by a small percentage to correct the fueling because I multiplied the entire Flex Fuel Spark table by .5?

12500 - Long Term Fuel Trim RPM Boundaries
or
12171 - Dynamic Airflow Zone - RPM Boundaries
or
12172 - Dynamic Airflow Zone - MAP Boundaries

It looks like some boundaries were changed at some point in those tables. One of those tables might get your FTC back to what you expected.

I looked at these and compared them to an old tune when it was working and nothing was changed it has all the same values.

[eXo3901]

I looked at these and compared them to an old tune when it was working and nothing was changed it has all the same values.

I opened the tune you posted and loaded the Base from the change history as a compare.