VSS/DFCO on GMPP LS7 with E67 VCM

[midgetracr]

I have a GMPP Crate LS7 Engine installed in a midengine kit car that uses a Porsche G50 transaxle. A wheel with 36 square teeth has been installed on one of the half shafts that drives a rear wheel. A stock GM VSS sensor is mounted appropriately to sense rear wheel rotation. The VCM sends a proper vehicle speed sensor signal to my Motec digital dash/data logger thru the OBDII port for proper speed and odometer readings. Everything seems to work fine. EXCEPT that Deceleration Fuel Cut Off does not work. ALSO my engine coolant fans properly turn on at 203* and off at 196* but do not turn off when vehicle speed exceeds "X" MPH as they should.

I've searched the forum but find no answers to my dilemma.

My questions are:
1. Does anyone have an LS7/E67 running with VSS, DFCO and fan cutoff all working?
2. If so would he share his .hpt file?
3. It is possibly a GMPP issue that has been fixed but I cannot find any GMPP LS7 tunes in the repository. My VCM was purchased several years ago.

Any and all suggestions will be appreciated.

Thanks

[DSteck]

You need to post the file.

[midgetracr]

File attached. Thanks

[ecotec88fiero]

Never mind, they are enabled I just looked at the wrong calibration.

[schpenxel]

Gtm?

[NTIMID8]

If you are using a true GMPP control calibration, a TON of stuff is disabled/non functional.

[midgetracr]

The original cal came from GMPP. There have been several (conservative) changes to ignition advance and AFR. In addition I have made numerous changes to the speedo section. The speedo section of the cal now matches a calibration I found from a 2012 LS7 Vette on the repository. Nothing seems to make a difference.

[ecotec88fiero]

Do you have a log of when it isn't going into DFCO?
Coolant temp, cylinder airmass, throttle position, and vehicle speed should be logged as well as fuel system status and fuel trim cell I think.

Everything looks enabled in the DFCO section but maybe something isn't properly being met to enable it if it truly isn't being enabled.

I don't see a section in the fans to turn off the fans above a certain speed but maybe I have missed that.

[grubinski]

Do you have a log of when it isn't going into DFCO?
Coolant temp, cylinder airmass, throttle position, and vehicle speed should be logged as well as fuel system status and fuel trim cell I think.

Everything looks enabled in the DFCO section but maybe something isn't properly being met to enable it if it truly isn't being enabled.

I don't see a section in the fans to turn off the fans above a certain speed but maybe I have missed that.

Ancient thread, but I don't see a resolution here. I'm trying to enable DFCO on *my* GMPP E67, and I'm starting to think that it's turned off in the GMPP controllers.

OP, if you're still here, did you ever get DFCO to work? Did you (or anybody else) find out if DFCO is disabled in GMPP engine controllers?

[blindsquirrel]

https://forum.hptuners.com/showthrea...on-Issue-Fixed ?

[grubinski]

Thanks for the help.

My VCM scanner shows MPH all the time (no actual speedo in this car). So the ECU doesn't seem to lose mph as in the thread you referenced. Also, my tach works fine.

Neither the thread you referenced, nor the thread referenced in that thread, say anything about DFCO.

Am I missing something you intended me to see?

[blindsquirrel]

Post #3: "Now my DFCO, reverse lockout, and gear dependent tables all work right! Thanks!!"

Point being, those GMPP things are very weird in unpredictable, undocumented ways, in that changing one little thing like the VSS/speedo configuration, can cause some other seemingly unrelated thing/things to quit working. Have you changed the VSS config at all?

If it was me, I would toss the intentionally-crippled GMPP thing in the trash (or Ebay, same thing, lol) and use a production-based E67 & OS compatible witht he rest of your parts, or you'll be chasing ghosts like this forever.

[blindsquirrel]

I don't know, but suspect, that a lot of the issues are down to the HPT editor not accurately reflecting the actual limits of the special GMPP hardware. In other words the editor will let you input a number in the box that the ECM can't physically use. The fan controls are a prime example. You can select PWM Electric in the drop-down, but the ECM isn't capable of outputting a variable speed PWM signal on the fan pins, it can only do on/off discrete relay fans.

[grubinski]

Thanks very much for the explanation.

I **have** changed the VSS config. So I will scale it as suggested in that post, and see what happens. It's possible I'll be looking for a production ECU.

Do you happen to know off the top of your head if the GMPP ECU uses the same pinouts as production E67 ECUs? I was looking at the pinout GM supplied me for the harness, and there is no CFCO pin on the ECU, even though it's supposedly possible to enable it in the tune. I suspect the production harnesses have it. If I just slap a production ECU in there, and the harness isn't compatible, I could wind up with *worse* problems. And if I'd have to rewire the whole thing anyway, that makes me wonder about a Holley or Megasquirt ECU. I went GM to start with because it was the quickest way to solve the problem. But it may introduce it's own problems.

Thanks again for taking the time to answer this. I will report back to this thread (and my original) with results.

[blindsquirrel]

Do you mean: there's no wire shown at the location for the clutch switch in the diagram, or: the pin is physically not present in the ECM at that location? If it's the first one you can always add your own wire to the connector, if it's the second then no-go.

I don't have any factory diagrams that go up that high, mine stop mid-2009 and I can't think of anything '08-earlier that used both E67 and manual trans. XLR & TBSS were auto trans only for the years I have coverage on, and the '09 CTS section omits the -V parts. Sorry!

[grubinski]

Do you mean: there's no wire shown at the location for the clutch switch in the diagram, or: the pin is physically not present in the ECM at that location?

I don't find a wire for CFCO in the ECM pinout that I have as part of the controller docs. Mine is a relatively early ECM, I bought the crate motor and controller in late '09.