Flex fuel DBC OS

[turbo_bu]

Starting to try and figure out how to get flex fuel working using a 512 KB PCM. I have found the couple of L59 OS's over on the Tune Depot, but noticed that those are for a DBW setup. Internet reading says that you could have an L59 in either the truck or SUV. The Tahoe/Yukons were some of the 1st vehicles that got the DBW. I am hoping that maybe a Silverado L59 would still of had the DBC. Does anyone have a copy of an 512 kB L59 OS which still used the DBC? The couple of files which people have shared on this forum have also been DBW. I would prefer to try and keep a DBC setup instead of the DBW.

[Chevy366]

Just kind of wondering why DBC versus DBW? You do know that you can adjust the DBW in most tune files to mimic DBC responsiveness?

[Taz]

... The Tahoe/Yukons were some of the 1st vehicles that got the DBW. I am hoping that maybe a Silverado L59 would still of had the DBC ...

With 2002 Flex Fuel trucks (OS12216125) the DBC vs DBW option is not a matter of early vs late production ... it is a function of the Traction Control option. If the truck came with the Traction Control option, then it will be DBW. If the truck did not have Traction Control, then it will be DBC.

E85 has never been available here ... so I have never given Flex Fuel tuning much attention.

[Taz]

Just kind of wondering why DBC versus DBW? You don know that you can adjust the DBW in most tune files to mimic DBC responsiveness?

Funny you should mention that ...

In some custom vehicles controlled by a PCM (512 Kb or 1Mb), using a DBW setup would be easier to engineer, and offer "free" Cruise Control. Some people stalwartly push a DBC install (even when it is more work) because they were told DBC is "better" at their local coffee shop by some unknown subject matter "expert".

[DURAtotheMAX]

In some custom vehicles controlled by a PCM (512 Kb or 1Mb), using a DBW setup would be easier to engineer, and offer "free" Cruise Control. Some people stalwartly push a DBC install (even when it is more work) because they were told DBC is "better" at their local coffee shop by some unknown subject matter "expert".

x2! Drive by wire all the way. Who wants to screw around with routing/mounting a throttle cable in a custom swap vehicle? I built a 1968 VW Beetle on a Jeep CJ7 frame with a Gen III 5.3 in the back....DBW was a godsend because I would have needed a 15+ foot long throttle cable to get to the rear mount engine.

[turbo_bu]

I understand that with DBW you can hook it up without the hassel of a throttle cable or cruise control module, but for some of the swaps that I have done, not having to mess with a TAC and DBW TB have been kinda nice too. Most of the time I end up piecing something together and not having the luxury of a complete take out (PCM, TAC module and matching engine). So, having a DBC setup works pretty nicely. Just need a 0411 PCM and a harness to re-work.

Taz, thanks for clarifying why it either had a DBW or DBC setup with regards to the traction control. I did not know that, but had heard similar logic with regards to later van OS's.

Has anyone happened to run across a DBC, L59, from a 512 kB LS1B PCM?

[Taz]

If Flex Fuel use is your goal, then the 2003 to 2005 truck components may offer the path of least resistance. In these years the APP (gas pedal) and TAC Module are interchangeable - they don't need to be from the same vehicle. Also there was no "special" Flex Fuel OS - they used the same OS an non-Flex Fuel trucks.

The APP and TAC (complete with harness) are very easy to remove from the vehicle - and these won't cost much from your local "pick your own part" wrecking yard.

With a DBC setup, if you wanted Cruise Control in your custom vehicle (many people do), you would have to add a Cruise Control Module - which is essentially a TAC Module with a cable protruding. This cable, and the throttle cable, both get attached to the DBC throttle body. For custom vehicles equipped with Cruise Control, DBW is far more user friendly, and easier to install.

Just my two cents ...

[turbo_bu]

Taz,

Thanks for the tip about the interchangability of the APP and TAC module on the trucks. I didn't realize that group of trucks interchanged. I have always just tried to keep everything together when doing a swap to avoid any issues.

I understand the pitfall of having to do not only the cable TB, but also the cable cruise control module. Luckily, most of the swaps I have done are on old vehicles (pre 1980's) so there is reasonable amount of room to mount stuff. I would still like to find a DBC OS just so I have the option of keeping the cable TB. The current swap I am planning will most likely be a DBC just due to the parts that I have to work with.

[Taz]

Roger that ...

One final suggestion .... try and obtain the Flex Fuel sensor from the donor vehicle. The 2002 to 2006 variant is nearly $800 from GM, although these can often be found in the $300 to $400 range from other sources.

[gpr]

Did you ever find a 512k OS for an L59?

If the OS is DBW, can you convert it to DBC? I would like to do the same thing by installing a flex fuel sensor and Flex Fuel OS on a 411 pcm that is DBC, but need to find an FF OS that is 512k and be converted to a COS for 2 or 3bar.

[turbo_bu]

I did find a DBC 512 kB L59 file on another tuning website in binary file format. It came from a 2002 K1500 Silverado, L59 (5.3L) with automatic transmission (12216125 OS). The only issue is that EFI Live does not have a COS for that OS. There are COS's for other OS's in 2002, just not the one that has the flex fuel turned on. From what I could find, all of the flex fuel OS's in 2002 are 12216125.

The other option is to go to a 1 MB PCM (2003 and newer). There are several flex fuel files out there, but of course, all of those are DBW. The good news is that there is a COS available for the newer flex fuel OS (found a 2003 and a 2004 that would work). The bad news is that they are all DBW. The only thing I could not verify is IF the van's had flex fuel as an option. If there was a van file with flex fuel, it "should" still have a DBC setup. The wild card with vans is that apparently some had traction control (stabilitrac I think) which required a DBW setup. Thus the van can have a DBW setup too :(

One interesting thing, while I was posting around trying to find the 512 kB file, one tuner said that you could turn off the DBW option. I have never tried this yet, but the jist of it was to turn on/off the DTC's and to fill in the necessary tables. Of course you still have to make sure the 1 MB PCM has the IAC driver hardware too, but otherwise you "could" change a DBW OS into a DBC OS. Again, I have NOT tried this yet, but that might be the only option. Get a 2003+ DBW flex fuel OS .... change it over to DBC in EFI Live .... flash it into a compatible 1 MB PCM .... then do the COS upgrade.

One last thing I should probably add for those looking into this is regarding the flex fuel sensor. From what I have read, the specs on the "old style" sensor ($400 - $600) and the "new style" sensor (~$40-50) are same. Both take +12 volts to power them, and they both output a 0-5V square wave signal. One guy even bought an old style sensor to try it out on his newer E38 ECM and it worked. The reason why he started with the old style sensor was that the old style sensor was supposed to be more reliable / robust than the newer cheaper ones. I have not seen that mentioned anywhere else, but the price difference is HUGE.

[turbo_bu]

Sorry, forgot to upload the tune file.

[gpr]

Yep looks like the only way to accomplish this is to change your PCM and run a 1mb OS system that will then allow you to run flex fuel and have a COS.

Searching on the topic it looks like the best and easiest path is to use PCM 12586243 from a 2004 GTO, and then you can run OS 12587604 which is a flex fuel OS and has a custom operating system as well. However doing this will require to move a few pins around in the PCM connector.

In theory this should work, however I haven't tried it nor seen anyone do it successfully.

[turbo_bu]

I might have missed something, but I didn't think that GTO's ever came with flex fuel? Were you thinking of segment swapping in the L59 engine portion? The couple of 2004 L59 OS's that I have seen (12587603 & 12606960) do not match up with the GTO OS.

Or were you planning on "turning on" that portion of the code in the GTO OS? I didn't think that this was an option and that you had to start with a flex fuel OS to begin with ???

[gpr]

I might have missed something, but I didn't think that GTO's ever came with flex fuel? Were you thinking of segment swapping in the L59 engine portion? The couple of 2004 L59 OS's that I have seen (12587603 & 12606960) do not match up with the GTO OS.

Or were you planning on "turning on" that portion of the code in the GTO OS? I didn't think that this was an option and that you had to start with a flex fuel OS to begin with ???

the GTO's did not have a flex fuel option, however they are a 1mb pcm and are wired very similarly to the 411 pcm. Thus there would be a few pins to change around in the pcm harness, but then you can install the 1mb OS that is flex fuel capable onto that PCM. Plus there is a COS for the 604 OS i listed above.

I believe this will work, but i haven't tried it yet.

[turbo_bu]

Yes, GTO is a 1 MB PCM with DBC from the factory. The issue that I am having trouble with is trying to find a flex fuel DBC OS from the factory. So far, all of the 1 MB OS's are DBW, not DBC. The good news is that they have COS's available, just not in a DBC format. That was why when I heard about converting a DBW OS into a DBC OS, it gave me hope. I am still very leary of whether or not it will work, but it might be something to try if you have a spare 1 MB PCM laying around.

That's also why I am curious about the Van OS's .... if they had a flex fuel option, then that would stand a chance of being a DBC setup with a 1 MB PCM from the factory! I just don't know enough about what options were available on the van's from 2003 - 2007.

[gpr]

Yes, GTO is a 1 MB PCM with DBC from the factory. The issue that I am having trouble with is trying to find a flex fuel DBC OS from the factory. So far, all of the 1 MB OS's are DBW, not DBC. The good news is that they have COS's available, just not in a DBC format. That was why when I heard about converting a DBW OS into a DBC OS, it gave me hope. I am still very leary of whether or not it will work, but it might be something to try if you have a spare 1 MB PCM laying around.

That's also why I am curious about the Van OS's .... if they had a flex fuel option, then that would stand a chance of being a DBC setup with a 1 MB PCM from the factory! I just don't know enough about what options were available on the van's from 2003 - 2007.

How do you even know if it is DBW or DBC in the OS? The OS's seem to be the same, and the only place i see any difference in the OS is the vehicle platform options and you can tell it yes or no on if it has electronic control. I don't have a pcm here i could test with on changing this to see if by changing this option the PCM would then start controlling the IAC for the DBC.

If someone could test this and verify the OS will work on DBC or DBW then adding flex fuel this way should work.

[turbo_bu]

The option list under vehicle platform is where I check to see if it is a DBW or a DBC setup. There are a couple of other tables too that end up having some different values in them, but the vehicle platform options is where I look first.

As far as making sure you have the correct 1 MB PCM, the guy on LT1Swap.com has a nice write up telling you what to check for as well as PCM part #'s.
http://www.lt1swap.com/cable_conversion.htm

Unfortunately, I too am in the same boat as I only have a couple of 512 kB PCM's laying around. I need to go out and find a compatible 1 MB PCM to play with to see if you can convert a DBW into a DBC OS.

Anyone have information about Van OS's ... and what options they came with from the factory?