Inconsistent Idle AFR - ECT compensation issue?

[Danielr96]

Hi Hondata,

I have been working on tuning my car and I would like to see if anybody would take a look at my calibration and give me some tips on how to optimize it. The setup consists of a stock longblock turbo d16z6, rc650cc injectors and motorola 2.5 bar map sensor.

Part throttle AFR's have been pretty good, near 14.7 but I have had this issue where I adjust my fuel table at idle for 14.7 AFR and it either leans out or richens up after turning the car off and turning it back on after 5-10 minutes. I have attempted to adjust my ECT compensation tables for this, but have not had much luck with getting my idle AFR spot on or steady at varying conditions such as temperature. I have also incorporated the correct injector deadtimes from the manufacturer for my given fuel pressure - it helped a bit, but not much. When tuning the car, I do my best to only make changes when the motor is fully warmed up and with constant ECT and IAT temperatures.

Also, is it normal if my 2-D fuel table lines get very close to one another? Especially through columns 7-10. I have attempted to smooth and interpolate my map in this area to fix the spacing, but the motor just seems to want those fuel values where the lines are very close. What can I do to make the lines have better "even-spacing" while maintaining the same AFR?

Any help is greatly appreciated. I am doing my best to learn how to tune and this is my first time reaching out for help because I am stuck with these small issues.

I have attached my calibration just in case anyone would be kind enough to look at it and give me some pointers.

[crluver123]

the lines are spaced differently because the map sensor values for those lines are not evenly spaced. it is completely normal, and should look like that.

as for the inconsistent idle afr, it could be a number of things, such as:
-injector latencies
-rc injectors don't have the best spray pattern/atomization
-iat temps

idle afr honestly isn't all that important. as long as it's between 13.0 and 14.7, it's fine. I usually set hondas up to idle around 14.3, as it seems thats what they like best, and that leaves some room for error for when it decides not to be consistent.
it's also fairly normal for it to idle much leaner after it's been shut off for several minutes and restarted, because the intake manifold heatsoaks and iat's read much higher temporarily until air flowing through starts to cool it back off again.

[Danielr96]

the lines are spaced differently because the map sensor values for those lines are not evenly spaced. it is completely normal, and should look like that.

as for the inconsistent idle afr, it could be a number of things, such as:
-injector latencies
-rc injectors don't have the best spray pattern/atomization
-iat temps

idle afr honestly isn't all that important. as long as it's between 13.0 and 14.7, it's fine. I usually set hondas up to idle around 14.3, as it seems thats what they like best, and that leaves some room for error for when it decides not to be consistent.
it's also fairly normal for it to idle much leaner after it's been shut off for several minutes and restarted, because the intake manifold heatsoaks and iat's read much higher temporarily until air flowing through starts to cool it back off again.

Thanks a lot for the clarification. Makes a lot more sense that the lines end up being spaced in that manner due to the map sensor's resolution.

I do have another question though -- I am now satisfied with how my fuel map is and I wish to run closed loop for fuel economy.

There are two sets of ECT fuel compensation tables, one for open loop and another for closed loop. Is it generally normal to set these tables to the same values for both open loop and closed loop conditions?

[crluver123]

honestly you'll need to experiment with that. different ecu's tend to have different open and closed loop conditions. for example, one ecu may run identical in open loop and closed loop, whereas another ecu may run normal in open loop and super lean in closed loop if using the same values. and everything in between. so just dial everything in while in open loop, then set to closed loop and adjust those values according to fuel trims, targetting zero% fuel trim of course

[Danielr96]

Hi guys,

I have narrowed down this issue -- what seems to happen is my idle could be at a solid ~14.7 while fully warmed up at 180*F ECT and 80-100*F IAT, but when I turn off the car and restart about 5 minutes later it while hot, it leans up to 18-20+ afr for about 30-60 seconds and it then stabilizes to the usual ~14.7.

I have added fuel on my IAT compensation tables, and although the numbers may seem a bit excessive above ~120*F, I still have the same issue.

My IAT fuel compensation table

Capture.JPG (19.99 KiB) Viewed 6426 times

Have any of you guys also had this issue? If so, what have you guys done to fix it? Or is it normal?

I have also attached my calibration.

[Danielr96]

Anyone?

What can I do to fix this lean hot restart issue?

I have decreased the fuel decay tables and added more post start fuel and I still haven't had any success in fixing this.

The car runs perfect, other than the lean issue upon hot restarts.

Thanks!

[Spunkster]

Post a datalog showing this.

[skaterguy1986]

I don't mean to thread jack but I also don't want to start a new thread when I'm having a similar issue but changing the IAT values didn't seem to do much. Which direction alters AFR? Moving the scale up I assume since that's a positive value and I'm guessing correlates to that number times the base injection value.

[Spunkster]

I don't mean to thread jack but I also don't want to start a new thread when I'm having a similar issue but changing the IAT values didn't seem to do much. Which direction alters AFR? Moving the scale up I assume since that's a positive value and I'm guessing correlates to that number times the base injection value.

Please start your own thread and give examples as well as calibrations and datalogs showing the issue.

[Danielr96]

Hi guys,

I haven't had much time to work on this car as I don't drive it much, but I will try to replicate the issue by next week and post a datalog so that it can be reviewed by Hondata.

[Danielr96]

Hi guys,

I finally came around to taking a datalog of my situation. This time it wasn't as bad, as I waited about 5 minutes before I did the hot restart. Although on occasions when I wait 20 minutes or so, the car starts up at full lean (20+ afr) and then it comes back down to the 14's after a few minutes.

Please review the attached datalog and calibration.

[Danielr96]

Here's another datalog of the occurrence, I've been stuck with this issue for quite some time and the car runs great other than this.
Which parameters can I change to increase the fuel during hot restarts?

[2x0]

You'll want to be watching your sensors and compensation values simultaneously when this occurs to determine whether or not they are a factor. What is your ECT and IAT reading when it happens? How much compensation is it putting in? Is your closed loop enabled and what is your S.trim?

Without tracking these before making any adjustments you are shooting in the dark.

[Danielr96]

You'll want to be watching your sensors and compensation values simultaneously when this occurs to determine whether or not they are a factor. What is your ECT and IAT reading when it happens? How much compensation is it putting in? Is your closed loop enabled and what is your S.trim?

Without tracking these before making any adjustments you are shooting in the dark.

I have been driving the car in open loop and the issue isn't as bad when running closed loop. If I remember correctly, when I was in closed loop, the S.trim during hot restarts would be in the neighborhood of +10-15%.

My ect and iat tend to be in the 185* F and about 135* F respectively, with a correction factor of 0%.

Therefore, this brings me to believe that it's due to a heatsoak issue, but I cannot seem to find the means to correct this.

Would it then be appropriate to add 15% fuel on the 135*f column of the iat.C? Or would I have more success using the post start fuel corrections (seems to only apply to cold starts, not hot restarts) or using the cranking fuel trims to add more fuel during this scenario?

[2x0]

If 185 ECT and 135 IAT are your normal warm engine conditions then both compensations should remain at 0% for those values. Post up your compensation parameters. It could be that your cold ECT and IAT fuel compensation is a bit high, which makes it start up cold and run well but once it is warmed up it actually needs more fuel in the fuel tables.

Also, running in closed loop would help adjust for whatever factors are throwing this off. This is the purpose of closed loop, because your table and parameter values will never be perfect for all conditions. Let the O2 sensor feedback do it's job under normal driving and idling.