Nistune Forums

martin7937 wrote:

Matt wrote: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).

Alpha/N Increase Fuel map the same as or a revision of the Acceleration Inrease Fuel table

So The VE Map is accessed on top of the fuel table when the TPS is below the line in the Alpha/N Increase Fuel map, correct?

Once above the TPS level indicated, the Ecu refers only to the fuel map?

But setting the Alpha/N Increase Fuel map to 255 across the board

This does not make sense since now we would always be below the Alpha/N Increase Fuel line.

Matt wrote:

Alpha/N Increase Fuel map the same as or a revision of the Acceleration Inrease Fuel table

Yes it is the same

So The VE Map is accessed on top of the fuel table when the TPS is below the line in the Alpha/N Increase Fuel map, correct?

This is correct. I have noted that below this line the VE map coefficient is added to the fuel map coefficient

Once above the TPS level indicated, the Ecu refers only to the fuel map?

To be confirmed that it is not completely accessed

But setting the Alpha/N Increase Fuel map to 255 across the board

Is done for vehicles which are turbo charged and do not have VE maps

R34 Skyline for example has fuel + VE maps and this table is
126 126 126 126 158 190 190 190 190 190 190 190 190 190 190 190

Which is the point between VE+Fuel and Fuel being used.

This does not make sense since now we would always be below the Alpha/N Increase Fuel line.

Only for the earlier vehicles without VE maps, which access the last column only once above this line

Matt wrote: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)