2008 E38 will not crank

[Alvin]

I've got a swap vehicle here with a LS3 crate engine in it. The controller that came with the engine came from a company who used a 2007 OS in it. It had all kinds of issues so I thought I would start off by dropping a stock 08 cal in it with the vats and starter checks disabled.

It absolutely will not fire. Has anyone else had this issue? What should I try

[WS6FirebirdTA00]

Is the car doing anything? Does the fuel pump prime? I assume you can still connect, read, and write or no?

[Alvin]

Yeah, I can flash it back with what it has and it runs. its cranking, just not firing

[Chris@HPTuners]

try logging the fuel cut type PID.

[Alvin]

Good idea..

I get none when the engine is off key on. When I try to crank I get "??? - 20"

Any ideas?

[Chris@HPTuners]

It's an Electronic Throttle low voltage fuel cut

[Alvin]

Why would it do that? I've gone back and forth between the 2006 OS and it works fine.. The 2008 gives me the error. Should I check to see if theres a DTC difference especially regarding ETC?

[Chris@HPTuners]

i dunno exactly but from what i can see it would happen if the ignition voltage is below around 6-7V on whatever inputs the PCM looks at (i think there are two inputs that are monitored). What i do know is that Speartech has this OS working fine with their setup. I did the starter OS patch for them and it was all systems go. Sounds like a wiring issue.

Oh yeah BTW, the earlier OS's don't have this check or fuel cut.

Chris...

[Alvin]

Hey, I spoke to John at Speartech and he said no additional inputs or anything where needed for the 2008 OS's. He said all he had to is disable the starter checks.

I got it to crank and run once with a 2008 OS manual file.. Now its back to the same ole same ole.

[Alvin]

argh..

I think I figured out what is going on. With the LS3 operating system it wants to see X voltage before it will fire. The older LS2 systems don't care. this car is wired with a single 0 wire going up to the starter then a smaller wire coming up to power the accessories and PCM. I believe when the starter first hits the voltage at that pole is just a bit too low and the PCM will not fire. The car turns over great and quick enough it just will not fire. Put a jump box on it and she cranks right up.


I've been driving it all afternoon with a LS3 OS and besides long start times when voltage spikes low she drives like a stock car.. just like it should

[Chris@HPTuners]

i hate these kinds of issues, glad you got it sorted

Now give me some advice on curing this misfire i have on my 408 LS1 at 14psi equally frustrating!!!

[Alvin]

Post your file

LOL.

Shouldn't be that hard.. I'd use a NGK BR7EF @ .028 and let her fly. Sometimes fueling can be so far off the wideband looks sorta right but is completely out in left field. Have you tried adding a good bit of fuel and see if it clears up?

[Chris@HPTuners]

yeah was just kidding, it was one of those late nights on the dyno where everything that could go wrong did! in the end we decided that night was cursed and to try again another day, LOL!

[RomansDesigns]

It's an Electronic Throttle low voltage fuel cut

Any way to turn off this code? I've had a couple of cars that I had to convert to 2006 LS2 Code to get to run... not ideal...

[imaboa]

I had a very similar issue w/ a swapped car using the same PCM.

Looking over the wiring diagrams, we figured out that it had something to do with one of the security features. The ECU needed to think the key was physically in the ignition. I forget what exactly we put power to or grounded and the issue was resolved.

[Jp Tech]

GROUND the yellow and black wire to start and fuel realy