ECU with enabled VE map-fuel issues

[raddy]

Hi all

As was already mentioned here: viewtopic.php?f=11&t=1115&start=15

there are some ECUs-in my case Almera N15 SR20DE, ecu 1N4XX- that have enabled VE map. Another point is that this ECU have enabled O2 flag in entire fuel map. Now my issue-simply said, this ECU does not respond to values in fuel map at all... Im able to affect AFR by K konstant and by altering VE map. But even in VE map, I dont understand exactly how it affect AFR, as reaction is like random and I didnt found any system here... With connected OEM labmda, I dont have an issues with idle or with crusing, but full throttle AFR is somehow generated...Change of VE map will affect AFR, but it is really not possible to set whole load range to desired AFR. VE map have different RPM/load scales, spacially RPM scale is limited to 6375rpm, however rpm limiter in my case is at 8500rpm... I would really appreciate any help or input here...Thanks a lot


just to add that N15 Pulsar/Almera SR20DE ECU 0A5XX, 1N96X, 1N97X doesnt have VE table nor O2 flag in entire map...

[Matt]

I've found that the VE map is actually based from TPS not TP over the last few weeks when getting K11 Type 5 working

I've updated the tracing accordingly now in the 0.12.11 version of Nistune.

Let me look into these models today to verify the other tracing for fuel maps and scalings is correct

[martin7937]

That explains pretty much everything.....

Matt, please look into 23710-83J00 ECU also.

[Matt]

Okay I've ran out of time today and busy tomorrow so will be over the weekend. Trying to catch up since I have a few jobs dragging me back this week

[raddy]

Hi all, since will Matt come with solution, here is what I did with good result:
1, Whole VE table was set to 128
2, Whole fuel map was O2 enabled, as standard. However, narrow band probe is not present. Also, whole fuel map was set to 128 (or 0 filtered), except area of higher load, where I used higher values, very similar to stock map.
3, whole table Accel increase fuel vs TPS voltage was set for 2000mV. I have strong feeling that this table actually contain condition of TPS voltage versus use of VE or Main fuel maps. By my opinion its not obvious acceleration enrichment....
4, K was set that on idle and low load was real AFR same as fuel map AFR (area of zero value on map=14.7:1 real AFR), however on high load areas was real AFR differ from map AFR.

Suprisingly, this bring AFR to just right values for complete engine load, even 8500rpm was spot on. Before, it was very lean until 4000rpm (about 15:1, very sluggish engine power), then relatively rich until 8500rpm. Now, it was about 12.5:1-13.2:1 all the way, any hesitation was removed and engine is pulling strong and smoothly up to rev limiter.
Im still not able to affect AFR as I wish, but luckily AFR was just spot on at this case. Maybe this info will helps also to others. ECU was N15 1N4XX, engine SR20VE.

[martin7937]

Hi Raddy,

What you did is what I tried several times, with no success so far.
Currently my car runs sort of good and fuel consumption is acceptable. But as you mentioned, no matter what I do I still have the engine hesitating at certain RPM (between 1.800 and 2.800 RPM).
Also as explained, under 4.000 RPM it is hard to believe it is an engine making 160+ whp...
Idle issues are also present but they are something I can live with.

However, I don't think this is a reasonable solution.
By setting the VE table flat (128s all-around) and doing the same with pretty much the whole fuel map, it is really easy to find the proper K. But after that, when you try to set the cruise areas, at least in my case, it is impossible to go as leaner as I wanted. After certain point it felt like I am hitting certain limitations.

For me it is really important that Matt finds time to fix this issue. So far I've spent so much time, money and nerves trying to set things right, which turned to be impossible, only due to the wrong tracing. I will be really grateful if I am finally given a chance to tune my car properly. Although I am kind of tired already and I started thinking of selling the car and the board and leaving all this behind..

[nissangts]

Hi Raddy and Martin, is there any particular reason that you guys would want to shy away from running an earlier generation ecu with your current setup? Its something that many of us do simply because of the difficulties encountered in manipulating later ecus.

[raddy]

Hi Nissagts: you are completelly right, only reason in my case was that owner of car already purchased nistune board for his ecu, before we know these issues. Now he should buy new ecu with new nistune board, what is rather expensive, so I try to do anything to solve current situation. In my case it went very good, idle, cruise and full load is just spot on...Mentioned changes removed hesitation and engine run really very good and owner is satisfied..

Martin: I thing that critical table (in my case) was mentioned Accel increase vs TPS voltage. I think that this table currently force ecu to use VE or main fuel maps...

[nissangts]

Hi Nissagts: you are completelly right, only reason in my case was that owner of car already purchased nistune board for his ecu, before we know these issues. Now he should buy new ecu with new nistune board, what is rather expensive, so I try to do anything to solve current situation. In my case it went very good, idle, cruise and full load is just spot on...Mentioned changes removed hesitation and engine run really very good and owner is satisfied..

Martin: I thing that critical table (in my case) was mentioned Accel increase vs TPS voltage. I think that this table currently force ecu to use VE or main fuel maps...

Ohhh ok I understand that. I suppose in the future you guys might want to your customers to go the early ecu route, works a lot easier

[Matt]

Sorry still to look into this one. Its on my investigate list

[martin7937]

@nissangts: Same here. As raddy already explained, back in the time when I was purchasing the board, I was so not aware of the issues with the VE table. I recently tried the earlier ECU on my car and it runs good. But it is too late now. Hopefully we will have this clarified soon.

@raddy: I will look in the table Accel increase vs TPS voltage. What I remember is that I messed a lot with it and still with no result. At certain points I was getting horrible feedback from the WB, thus I decided to leave the table alone. Will give it another try.

[Matt]

1N4XX ECU/83JXX ECU

Now my issue-simply said, this ECU does not respond to values in fuel map at all.

whole table Accel increase fuel vs TPS voltage was set for 2000mV. I have strong feeling that this table actually contain condition of TPS voltage versus use of VE or Main fuel maps. By my opinion its not obvious acceleration enrichment....

As you have found Fuel map / VE usage is dependent on the Acceleration Increase fuel values. In older ECUs this table was used to use the TPS voltage to determine access the last column on the fuel map.

However with the VE map ECUs this table appears to determine if the fuel map values are used in addition to the VE map table. With my ER34 the AFRs at the lower end never needed adjusting so we did not noticed these same issues or needed to adjust the VE map. However I did note that adjusting VE did not have the expected effect. Now we know why since the table is TPS based

Accel enrich table
If you increase these (TPS) values for the specified RPM area then it will start using the fuel map in addition to the values in the VE map. This has been noted to work on the bench during investigations today

Note: The main thing during testing is monitoring the injection time (which consequently will be reflected by the change in your AFRs on the particular RPM/load point you are modifying)

Increasing the corresponding TPS value for the current RPM index on the accel increase table would make the ECU use the fuel map values as expected rather than trimming back on fuel map increase and just depending on the VE map values

Fuel map
It also was noted that adjusting the fuel map (increasing values) would actually reduce the injection time when O2 sensing feedback switch was enabled and the values in the Accel increase table were lower.

When disabling O2 feedback, the ECU is no longer looking at the O2 input and adjusting injection to maintain stoich trims. Same with increasing the values in the Accel increase table, the fuel map cell increases then took effect

VE map and trimming
Watch the injection trimming (AF alpha and AF alpha learn - short and long term trimming). Adjusting the VE map will result in additional trimming to occur in the map and injection to respond to making these adjustments. It may take upto 10-15 seconds for the ECU to monitor the O2 sensor and then adjust the injection to corresponding trimming (to reach 100%) as noted in the consult gauges (watch using the logger) in response to VE map changes

Trimming adjustments made by the ECU will affect all injection (global adjustment, similar to how K constant works). So watch for any trimming adjustments during tuning and then check the rest of the AFRs throughout the fuel map if the ECU has been trimming after VE map adjustments

Now if you are using the 0.12.11 version the VE map tracing has been fixed to follow the TPS position. I found that after bench testing that it will follow VE map changes. I noted today cells need to be changed one cell to the left of the cursor in this version. It appears maybe the trace needs to be moved left by onel. I will monitor next time I have the R34 plugged in

Let me know how you go given this information. All fuel map and timing scalers appear correct for these ECUs (so only inverted for K11 Type 5 ECU)

[nissangts]

1N4XX ECU/83JXX ECU

Now my issue-simply said, this ECU does not respond to values in fuel map at all.

whole table Accel increase fuel vs TPS voltage was set for 2000mV. I have strong feeling that this table actually contain condition of TPS voltage versus use of VE or Main fuel maps. By my opinion its not obvious acceleration enrichment....

As you have found Fuel map / VE usage is dependent on the Acceleration Increase fuel values. In older ECUs this table was used to use the TPS voltage to determine access the last column on the fuel map.

However with the VE map ECUs this table appears to determine if the fuel map values are used in addition to the VE map table. With my ER34 the AFRs at the lower end never needed adjusting so we did not noticed these same issues or needed to adjust the VE map. However I did note that adjusting VE did not have the expected effect. Now we know why since the table is TPS based

Accel enrich table
If you increase these (TPS) values for the specified RPM area then it will start using the fuel map in addition to the values in the VE map. This has been noted to work on the bench during investigations today

Note: The main thing during testing is monitoring the injection time (which consequently will be reflected by the change in your AFRs on the particular RPM/load point you are modifying)

Increasing the corresponding TPS value for the current RPM index on the accel increase table would make the ECU use the fuel map values as expected rather than trimming back on fuel map increase and just depending on the VE map values

Fuel map
It also was noted that adjusting the fuel map (increasing values) would actually reduce the injection time when O2 sensing feedback switch was enabled and the values in the Accel increase table were lower.

When disabling O2 feedback, the ECU is no longer looking at the O2 input and adjusting injection to maintain stoich trims. Same with increasing the values in the Accel increase table, the fuel map cell increases then took effect

VE map and trimming
Watch the injection trimming (AF alpha and AF alpha learn - short and long term trimming). Adjusting the VE map will result in additional trimming to occur in the map and injection to respond to making these adjustments. It may take upto 10-15 seconds for the ECU to monitor the O2 sensor and then adjust the injection to corresponding trimming (to reach 100%) as noted in the consult gauges (watch using the logger) in response to VE map changes

Trimming adjustments made by the ECU will affect all injection (global adjustment, similar to how K constant works). So watch for any trimming adjustments during tuning and then check the rest of the AFRs throughout the fuel map if the ECU has been trimming after VE map adjustments

Now if you are using the 0.12.11 version the VE map tracing has been fixed to follow the TPS position. I found that after bench testing that it will follow VE map changes. I noted today cells need to be changed one cell to the left of the cursor in this version. It appears maybe the trace needs to be moved left by onel. I will monitor next time I have the R34 plugged in

Let me know how you go given this information. All fuel map and timing scalers appear correct for these ECUs (so only inverted for K11 Type 5 ECU)

That's a lot of work to do just to tune these this kind of ecu.

[Matt]

Just remember that the VE map is used in cruise conditions. The accel increase map appears to be the TPS threshold at which the fuel map starts getting used

VE map trims additional fuel on top of the 14.7:1 stoich settings. VE map when adjusted will command these cruise conditions. You can always turn it off by disabling O2 flag and then just use the fuel map

Or otherwise adjust the accel increase map to use more of the fuel map instead if necessary

[martin7937]

Just remember that the VE map is used in cruise conditions. The accel increase map appears to be the TPS threshold at which the fuel map starts getting used

VE map trims additional fuel on top of the 14.7:1 stoich settings. VE map when adjusted will command these cruise conditions. You can always turn it off by disabling O2 flag and then just use the fuel map

Or otherwise adjust the accel increase map to use more of the fuel map instead if necessary

Just a quick note. I've always had my o2 flag disabled. If I understand correct the above, I've had the VE table turned off all the time. However, I was still not able to make changes in the fuel table which to result different AFR under certain conditions (mostly noticeable while in cruise).