Vortec PCMs

[EagleMark]

I've got a 1998 5.7L Vortec to play with. Looks like 1996 to 1999 is the year frame for this type? Are there differences in the years? Wondering if differant years can be re-flased or other displacements? Sure looks like my LT1 PCM...

On a side note, after I play with this for awhile stock... I got a crazy idea of COP like the LS engine! Have to look at wiring diagrams to see if stock harness could be used and how hard it would be to repin for 411 PCM.

[jameslleary]

no changes from 96 to 99. some 96 g3500 vans with the Vortec 350 had TBI and a 7427 Though....along with some export Tahoe and Suburban models.

[belaw]

some 96 g3500 vans with the Vortec 350 had TBI and a 7427 Though....along with some export Tahoe and Suburban models.

Any idea what bcc's they used?

[EagleMark]

We've got one here and use it for a baseline spark advance Vortec head swap.

[belaw]

We've got one here and use it for a baseline spark advance Vortec head swap.

That's exactly why I'm interested! So what is the BCC?

[EagleMark]

http://www.gearhead-efi.com/Fuel-Inj...ull=1#post2902

[belaw]

We've got one here and use it for a baseline spark advance Vortec head swap.

I loaded BRDW into TunerPro and (using $0D definitions) ran a comparison with BJYL, focusing on the spark tables. Even to my uneducated eyes the results were surprising; main spark tables were identical but the CTS spark advance table was very different.

[JeepsAndGuns]

Any idea what bcc's they used?

Possiably BNKM? BCC find lists it as being used in 95 and 96.
http://www.gearhead-efi.com/BCCFind/...shtml?BCC=bnkm

[pmkls1]

96-99 was the year range for the C/K pickups running the L31, but the G vans kept them until 2002. There aren't any noteable differences in the years, they were pretty much all the same for the most part. The 2500 series and up got 4 bolt main blocks (nothing special in all reality) and the cylinder heads had hardened exhaust valve seats that severely restricted flow and resulted in less HP than the standard version. The only PCM difference is with the G vans as the later models used a 411 PCM. There are a lot of resources on swapping to the 411 PCM into the trucks as it is fairly popular. I believe, though, that in order to use the coil-near-plug ignition system like the LS you must use a special crank reluctor that swaps in place of the original to provide a 24x ignition signal to the PCM. There is a site that specializes in these conversions http://www.eficonnection.com/eficonnection/default.aspx but you better be sitting down when you look at the pricing because it is definitely not for the budget minded individual. But, if you have OBDII tuning and reflash capabilities you can really improve the performance of the stock L31 without any major modifications. The biggest limitation is the stock intake and injector configuration but you have to start getting into bigger HP numbers that would require more than just tuning and bolt on mods anyway.

[CDeeZ]

Mark,

I know basically nothing about OBD2 stuff, but my friend has done exactly what you pondered: CNP distributorless ignition. He calls his engine the "LS31" (cross between L31 and LS1)

here is the article that he wrote detailing this CNP swap: http://www.gmtruckcentral.com/articles/24x.html

[EagleMark]

Cool, I look it over later. I just got wiring diagrams for the 1998 Vortec and 2001 LS engine. Thanks Robert!

I don't plan any major mods to this truck, it fills a basic need right now for transportation and a learning center. Since I have a Roadrunner swapping over to LS PCM and tuning live would be fun. May just use this truck as a hands on learning center to cover Vortec tunes then get one newer with LS engine.

[EagleMark]

What about transmissions? I know pre- 1994 had a couple changes and 1995 4L60E were PWM TCC differant, then I think they were all the same in 1996 up?

[pmkls1]

There are some part and PCM programming differences after 96 as well. Around '98-'01 they used what was called an EC3 converter lock up strategy and I am unaware of the entire range of differences, but I know that there were pump differences and changes to the PCM code. Replacement pumps from GM will work in multiple applications and come with instructions regarding the installation in each particular application. There are also differences in the transmissions used in LS equipped trucks. Although LS style engines have the same bellhousing bolt pattern as the standard V8 chevy, the bellhousing depth is much shallower in LS applications. You can swap in a transmission from a different application regardless of which way you are swapping, but it requires the use of adapters available through GM. Basically, unless you know of the particular differences between different years and applications it is best to stick with a trans from a like-vehicle in order to avoid problems that arise from compatibility issues.

[belaw]

Mark:

I don't even know if there's a hack for the OBDII PCMs, but could you possible extract the MAF flow/frequency table data?

I've found tables for just about every other MAF except for the one GM used with the L31! (And yes, I'm off on another tangent...)

Brian

[EagleMark]

I'll let you know when my EFI Live get's here...