Changed Tune from MAF to SD mode and suddenly AFR went horrid, Help Please

[Dave_In_VA]

I've been working on a tune for a 2005 corvette, H/C/I car. This is a e40 ECM, one year only.

In MAF the mode, the idle is a little rich, about 13.8, the tip-in response goes lean for a few seconds, and then the AFR goes in the mid-12s to high 13s depending on load and RPM.

My MAF tune was pretty close to spot on, slightly rich from 2350 hz to 8200, from 0 to 3.1 rich. Only two spots of slightly lean (0.3 and 0.4 respectively).

See #25 log file. The tune is also #25. The VE table is from a mostly rich SD tune I did with same car last fall.

All I did was to change the MAF Freg Fail High to get it into SD mode.

The SD mode is tune # 26 and the log is 22-04-04 14-19-02.hpl.

With the engine in MAF mode, the AFR was 13.8 and with it in SD mode it was 15.6.

I was scared to drive the car so I changed it back to MAF to drive home.

The MAF only log showed the VE variances to be pretty good.

What is going on?

Smart people help please...

Dave

[SultanHassanMasTuning]

your SD values are weird, are you running other than stock injector/ maybe LS3

[Dave_In_VA]

The short block is LS2, the top end is LS3, Cam is zero overlap hight lift. Injectors are stock LS3.

[smokeshow]

The MAF only log showed the VE variances to be pretty good.

Not sure what this means. Both logs show the VE airflow reporting significantly less than the MAF. Use the method I documented to correct this.

[Alvin]

You can calculate GMVE from MAF to help fill in the VE table before turning the MAF off but that setup isn't that wild.

I would disable the MAF and just get started dialing in VE. unless it's black smoking out the back or spark knocking your not going to hurt it.

[Dave_In_VA]

Not sure what this means. Both logs show the VE airflow reporting significantly less than the MAF. Use the method I documented to correct this.

I assume this one: https://forum.hptuners.com/showthrea...orrect+airflow

[smokeshow]

I assume this one: https://forum.hptuners.com/showthrea...orrect+airflow

Yes. The idea is if your MAF is available as a reference point for airflow, then it can be used to correct the VVE. No fuel trims are even necessary unless the MAF calibration is not accurate.

[Dave_In_VA]

Thanks Smoke...

I'll work on this tomorrow or when our rain stops.

Another question, my idle AFR is rich - 12s, I would think 14.7 would be target.

Could this be caused by big difference in VE and MAF airflows?

Or do I have a bad setting? Thank you.

[eXo3901]

Your injector data is wrong and does not match LS3 injector data. Your MAP sensor data is wrong. It reads 84kpa with the engine off and your baro reads 84kpa. Should be close to 100kpa KOEO. Fix those things and re-tune the MAF.

[Dave_In_VA]

eXo,

are you suggesting I change all of my LS2 injector parameters to LS3 parameters, i.e.:






PS - The compare file in the picture is a stock M6 LS3 corvette.

[eXo3901]

These tables in your E40(E38 table, if different): 12311(12307), 12319, 12315, 12303, 12310(12308), 3055, and 12314. Just those related to the actual injector, not the injection timing. You need to convert the E38 data to E40 data since the E38 is pressure delta. I think I have seen someone post an excel file around here before if you wanted to search for that.

[blindsquirrel]

This is a conversion, done manually, using a 2010 Camaro LS3 as the source data. (sorry, I was bored so just did it)

20220404 1325 - DF SD 26 - 12576341 LS3.hpt

[blindsquirrel]

The spreadsheet was made around 2006-2007 before the axis labels changed, so it doesn't really work on the late 127lb ECMs. No one's made an updated version since then. It's not that much work to do manually once you grok which tiny portions of the E38 tables line up with which rows in the much bigger Gen3-style tables. Then it's just interpolating across the unfilled cells.

[Dave_In_VA]

These tables in your E40(E38 table, if different): 12311(12307), 12319, 12315, 12303, 12310(12308), 3055, and 12314. Just those related to the actual injector, not the injection timing.

Thank you - will do

You need to convert the E38 data to E40 data since the E38 is pressure delta. I think I have seen someone post an excel file around here before if you wanted to search for that.

Sorry, but I'm a newbie... My ECU is E40, but I have a MAP sensor associated with a E38 later gen 4 C6 corvette (e.g. 2009).

Below are screen shots from my current tune and a stock 2009 tune.

Can I use stock 2009 MAP and Baro values, or do I need to covert the values before I use them?

[Dave_In_VA]

This is a conversion, done manually, using a 2010 Camaro LS3 as the source data. (sorry, I was bored so just did it)

20220404 1325 - DF SD 26 - 12576341 LS3.hpt

Thank you, I see....

[blindsquirrel]

Be real careful about following the youtoob guides. There are things about the E40 that are different from everything else, and if you blindly follow a guide meant to be generic, or meant specifically for a different ECM, you gonna be all screwed up.

In particular I'm thinking about the layout of the E40's VE table... it's laid out backwards from everything else and lots of guides don't mention that. If you set up the graph axes wrong in the scanner, all your data will get pasted into the wrong cells in the VE table.

screenshot.08-04-2022 09.41.58.png

[eXo3901]

Can I use stock 2009 MAP and Baro values, or do I need to covert the values before I use them?

No conversion. You just need the data that corresponds to your MAP sensor. I do not think the E40 allows negative values, but the resulting error should be small enough to not matter. KOEO baro and MAP should be ~100kpa depending on your actual location.

[Dave_In_VA]

Hey Squirrel, Thank you.

And I have properly set up my scanner tables so the X&Y axis's match those in Editor.

[Dave_In_VA]

Here is my current tune.

I (hopefully) corrected injector parameters, MAP, and Baro values.

I also modified my Power Enrich which kicking in at idle and making it idle very rich (appx 12.5).

Any thoughts?

I'll load it after work. If it starts and idles well, I'll do a drive and log data (and then share).

Note, this is in MAF mode.

Dave

[blindsquirrel]

Note the little tooltip at the bottom of the window when you hover over something:

[ECM] 4012 - MAP Sensor Linear B: Should be set to 1/3 of MAP Sensor Linear value.

So. 0.00 is not 1/3 of 128.13.

That file still does not have the injector data copied in from the file I posted. Flow Rate vs KPA; Min Injector Pulse; Offset vs Volts vs VAC need to be updated.