Bad E38 ECM?

[Richard F.]

I have a constant MIL light on with no DTCs present at all. I thought it may be a harness issues, so I ran my own wire from pin 68(J1) to the instrument cluster, still no change. The ECM is constantly sending a ground from pin 68, and I cannot command MIL off with HP tuners.

Also I have PRNDL ?invalid? in the scanner, I?ve tried two different T42 OS?s still no change on that either. The E38 OS is 12617631, and T42 OS is 24239927, I?ve also tried 24235341. Do 4l80e?s need range a switch? I have P/N signal going to ECM. Just wondering if this could all be related to a faulty ECM?

[blindsquirrel]

Tune file. Log file. Year/make/model and any modifications from stock.

"E38" does not narrow it down much at all. Need real info.

[edcmat-l1]

Lemme get my crystal ball. BRB

[Richard F.]

Tune file. Log file. Year/make/model and any modifications from stock.

"E38" does not narrow it down much at all. Need real info.

It is a LS Swap with a 2.9L Whipple LS3 and built 4L80e. It's using a E38 ECM and T42 TCM controller flashed with a 2008 Savanna Van OS; the VIN number is 1GTGG25KX81151305. It has 80lb injectors, so I did scale the tune using by doubling the stoich and then cutting the flowrate and IVT terms in half. I haven't done much tuning on it, as I am still trying to work out any of the bugs before taking it on a good drive to get some tuning done. I've done a few Gen 4 E38 swaps without any issues; however, they were all manuals. I am attaching the Tune and a Log File below, let me know if out left out any important information that you need.

[veSS]

quick look at your tune and log, you have 10 degrees of knock in boost, your high octane table is too aggressive and you have PE/COT adding spark as well

[edcmat-l1]

quick look at your tune and log, you have 10 degrees of knock in boost, your high octane table is too aggressive and you have PE/COT adding spark as well

Even worse than that it's dead ass lean in boost @ 3000 rpm. Check at the cursor.

155 Kpa, dead lean and about 23 degrees of timing commanded. The CEL circuit is the least of OP's problems.

Lean at cursor.jpg

[edcmat-l1]

THE CEL is most likely lit up because it has the MAF failed but all the MAF codes set to no error reported. Set them to "MIL on first error" then uncheck the SES box. Bet the light goes out.

[edcmat-l1]

THE CEL is most likely lit up because it has the MAF failed but all the MAF codes set to no error reported. Set them to "MIL on first error" then uncheck the SES box. Bet the light goes out.

^^^ Once you do this, it's gonna run pretty bad. The VVE table is less than accurate.

Whipple VVE.jpg

[Alvin]

I have a constant MIL light on with no DTCs present at all. I thought it may be a harness issues, so I ran my own wire from pin 68(J1) to the instrument cluster, still no change. The ECM is constantly sending a ground from pin 68, and I cannot command MIL off with HP tuners.

Also I have PRNDL ?invalid? in the scanner, I?ve tried two different T42 OS?s still no change on that either. The E38 OS is 12617631, and T42 OS is 24239927, I?ve also tried 24235341. Do 4l80e?s need range a switch? I have P/N signal going to ECM. Just wondering if this could all be related to a faulty ECM?

It looks like other people have found issues that would cause a legitimate SES light.

In the case of the SES light being on (sometimes dimly) in a swap car.. its because a LED needs such a small amount of forward current to illuminate that the PCM is never truly air tight OFF. You can fix this with a pull up or down resistor. If you post the schematic for the light I can edit it for you. I can show you where to add a resistor/power ground and fix it.

Again this is only for situations where the scanner is saying the light is OFF but the check engine light (led) is ON, or dim

[Richard F.]

^^^ Once you do this, it's gonna run pretty bad. The VVE table is less than accurate.

Whipple VVE.jpg

I am no where near an experienced tuner lol, it will go to an experienced tuner with a dyno and let them dial it in properly. I wanted to get the engine started and idling to work out any potential issues before taking to the tuner. I haven?t done any other revisions to it since getting it started and idling; that log was the first test drive to the end of the street. I completely missed that the MAF is failed still Im sure that?s the issues with the CEL also. Thank you! I just have to figure out the PRDNL issue next.

Also, I will definitely take some timing out and adjusting the fueling in boost . If you don?t mind me asking, being that I doubled my stoich how do you get correct histogram readings for the graphs containing commanded AFR or AFR Error. Possibly Copy and paste into excel, and then half that data? Thanks for the Whipple VVE graph and tuning advice also!

[Richard F.]

It looks like other people have found issues that would cause a legitimate SES light.

In the case of the SES light being on (sometimes dimly) in a swap car.. its because a LED needs such a small amount of forward current to illuminate that the PCM is never truly air tight OFF. You can fix this with a pull up or down resistor. If you post the schematic for the light I can edit it for you. I can show you where to add a resistor/power ground and fix it.

Again this is only for situations where the scanner is saying the light is OFF but the check engine light (led) is ON, or dim

The car has a Dakota digital HDX, I haven’t had any issues with them in the past on swaps. The MIL output wire from the ECM goES directly to the Dakota Digital control box. I think edcmat may be on the right path.

[blindsquirrel]

Not one single change to fail the MAF was done correctly. Min RPM, high/low counts, dynamic disable/reenable, the DTCs...

[Richard F.]

Until 2 days ago the car had no physical MAF sensor, but the engine ran fine. Added the MAF to start tuning it as people said that wasn’t start with than the VVE, but was having transmission shift scheduling issues. I thought it was MAF/ incorrect load issues so I started disabling all kinds of stuff to do with the MAF to see if that would change anything. I had the OSS wrong enabled in the wrong location in the Tune. That ended up fixing my issues there. The MAF stuff completely slipped my mind after the OSS. I will fix that issues blindsquirrel, trying to tackle so many issues at once i forgot.

[Richard F.]

Again this will go to a professional tuner once the hardware issues are fixed!

[TheMechanic]

Use a bidirectional scan tool and command the light on and off to determine if
1. The ECM has the ability to turn on and off the light to verify wiring and bulb condition.
2. The ability to drive the light at the ECM pin.