Looking for expert Help

[tracykeyes]

Ok, I just purchased EFI live becuase I am having an issue with LS1 from a 97 vette. It is currently in a kit car so I am not using a BCM. The problem is it sarts then dies after2-3 seconds. Sounded like VATS to me. So I used EFI to check the VATS. It is disabled in the PCM. Now here comes the Expert part!
It appears that when I have an OBDII tool EFILive or other connected to the engine it starts and runs fine. When I remove an OBDII tool the engine goes back to start then die. I tried this numerous times times to validate and it is a fact. When OBDII is connected to a tool the engine runs fine. Very wierd! So I guess my question to you guys is this? Is this older PCM looking for another serial data connection before it will allow the motor to start? If this is correct then is there a way to disable this function or trick it into thinking it is there!
Ok, let the comments and questions fly!! Thanks all.

[Tordne]

So to disable VATS you changed G1201 to "None"?

Very interesting if what you are seeing is correct, that there is a difference to the running when a tool is connected. Also, to verify by connected do you simple mean that the EFILive OBDII cable is plugged onto the OBDII connection, or that you have actually established a connection to the car from the scan tool (through the FlashScan interface)?

Cheers,

[tracykeyes]

Yes the G1201 is set to none. It was this way when I first read the PCM. So my kit factory did disable it. I was using my PC and the ScanTool/EFILive OBDII plug in the OBDII port. It was connected because I was able to disable DTC for a non-existant auto tranny. Also used the scan tool and cleared DTCs and to see which ones to disable. This same thing worked with my other NON-EFIlive hand scanner.

I had another kit builder with the same year say he had to hook up a BCM to get his engine to run. He assumed it was VATS but I think it might be something else.

Wierd! I know but that is what I am seeing.

edit 1-- I think I under stand you question. I need to verify if it the act of pluging in a OBDII plug or actually esablishing a connection is what causes the engine to run..


edit 2-- Ok just tested again. It is actually the establishing a connection to the PCM the allows it to start. Just plugging in the OBDII connector does nothing.

[Tordne]

Is it just plugged on to the OBDII port, or actually connected. Subtle I know but could be significant. The EFILive scan tool connects when you press the tool bar button for instance. Until then not much is going on (at least I don't think so).

[tracykeyes]

Correct. I have to establish the connection before the engine will run correctly.

[Tordne]

Very interesting.. Any DTC's set at all?

[tracykeyes]

Not after I disabled all the auto tranny codes. The EBCM has some but I don't think that would matter.

[Doc]

So is this "Kit" car a manual(or some non electronic tranny)? Instead of disabling the auto codes why not just load a 97 Manual Trans OS(to bypass any possible interference)? Maybe it's not getting a tranny signal? Just a guess.

[tracykeyes]

That is a good thought. I had posted about re-flashing my PCM but I did not get a reply wether it was possible to flash a manual into a Auto PCM. If it is I will give it a shot.
Can I just reflash the PCM using the file on Holden Crazy and select "Program PCM operating system and calibrations"?

The kit uses a porsche G50 manual tranny and no electronics.

[Tordne]

You can absolutely flah an M6 tune over an A4. The PCM is just a hardware platform. It's kinda like you can install Windows 2000 or XP on a PC system.

So, yes you can take a base tune file from my tune site and full flash (OS and calibration) into the PCM no worries :)

[tracykeyes]

Great, that is what i was thinking but it would be a mess if I was wrong! Thanks. I will give that a shot later and post the results.

[tracykeyes]

ok, I have reflashed the OS and Calibrations to a manual transmission. I set the G1201 calibration back to None. I still have the same results. Darn!

[Tordne]

GRR :mad:

I have no idea then. Maybe PM GMPX or wait4me and see if they have any ideas...

[tracykeyes]

So what do you guys think about flashing a different 98 OS "19980400" to see if this changes the behavior? My current OS is "19980200"
Not sure if that can be done or if it should be done?

Edit--

I tried it anyway. The flash worked but did not resolve the issue. Doh!!

[tracykeyes]

Here is what I think is going on:

Under the DTC description I have it says:

DTC P1626 Theft Deterrent Fuel Enable Signal Lost
Circuit Description
The Vehicle Theft Deterrent system consists of the following components:

Powertrain Control Module (PCM)
Body Control Module (BCM)
Ignition Lock and Key
After the Body Control Module (BCM) has confirmed the key resistor pellet, the BCM sends a password to the PCM via the Class 2 Serial Data circuit. When this password matches the password stored in the PCM, the system enables the fuel. If the BCM does not send a password or if the PCM does not receive it, the vehicle will not start unless the PCM is in VTD Fail-Enabled mode. If the BCM and PCM loose communications with each other after the system has received the correct password, the PCM goes into VTD Fail-Enable mode. This allows the driver to restart the vehicle on future ignition cycles until communications between the BCM and PCM are restored. If the BCM and PCM loose communications before the PCM receives the BCM password, the PCM disables the fuel until communications is restored in order to prevent vehicle theft. In both cases DTC P1626 sets. The PCM will not disable the fuel injection once the PCM enabled the fuel within a given ignition cycle in order to prevent stalling as a result of VTD system faults.

I am not throwing P1626 but it seems like my problem. The scanner tools actually similate the BCM by supplying the password. At least that is my understanding. So maybe that is why only having a scanner connected to the PCM will allow the engine to start!
Would EFIlive developers know if VTD Fail-Enabled mode is being set by the G1201 setting? Maybe I should send them a note and see.

Oh yes and some did have validate that I loose ground to the injectors by using a light bulb test. So the fuel is being cut when it does not start.

[wait4me]

Is this an electric throttle car or cable? If it is cable, then put in a camaro manual program and try it.

If that dont work, then at one time that pcm had a checksum failure before you got it and that is what is shutting it down.

[tracykeyes]

wait4me - It is an electric throttle from the same vette. So would this checksum failure still occur if I reflashed the whole OS? I have done that and it seems like that would correct any issues from the previous car? Unless the reflash does not reset the entire PCM. The orignal corvette was having issues with running before I tore it down for parts. Would you have any suggestions other than getting a BCM?

[wait4me]

If the Computers EEPROM triggered the failure then you cant fix it. Even if the flash chip works.

[tracykeyes]

Thank you for the reply. Just so I can get a better understanding is there another chip on the board that contains this failure and therefor the setting remains even after the flash chip is redone. Also, is this only a 97/98 thing or does it cross all models?

[Doc]

This is deep. I am sure you can figure it out. Kinda reminds me of fighting with DOS. I just don't have enought life force left for those battles. Best advice I can give at this point is to migrate to a newer pcm/OS. I know that is not much of a help on the surface but if you want to persue it and are in need of pin swap, electrical help just PM me.
;)

[tracykeyes]

Well I just ordered a new BCM. I'll just wire in a resistor for the key and connect up the serial data wire. Bummer! I really wish I didn't have to use it.

[Rewire]

This an old thread but it is what I am experiencing except for the part about the pluging in..,..I cannot get it to run at all.

[joecar]

Is it possible to do a VATS/BCM relink (...is this the "password" relink...?...) from the scan tool...?

[Rewire]

We do not have the BCM so no relink possible. I don't understand why G1201 set at "none" does not work??

[joecar]

Oh, no BCM... I see.

[Doc]

Probably because the pcm is looking for a fuel enable signal that is produced by the bcm. DTC 1626 should set with this type of failure. If this is the problem you are going to have to find a way to get the 5v signal to the pin on the pcm.

Just curious, why did you choose to go with the 97 pcm? This might be a grand opportunity to get on the pinswap train to Custom OS heaven.

:cheers:

[Rewire]

It is actually a 98 and that was the total swap from a 98 Vette included computer. I rewired it to work in the Camaro. so you are suggesting I rewire it to run on a newer computer? It is a fly by wire btw.

[ScarabEpic22]

Yea, I dont know much about anything except the P10 LL8s, but from what Ive read on here get yourself an 02+ PCM and get COS instead.