doug_dayson

Anyone here convert a Speed Density L98 Vette to a boost aware 749 ECM?

Some F-Body folks have done it with the their 730's (non-hardened functional equivilent)...
http://www.speedtoys.com/~bort62/7749/Main.htm

...any gotchas (like VSS for shock and chassis computers etc)?

Can you put the 749's guts into the 727's hardened enclosure, and leave it in the stock location?

Thanks...

Doug

-=Jeff=-

All I do know ios you will no longer be running the $8d mask right?

If so, your CCM will not like it and you will always have the SYS ligth flashing.

In a vette the CCM is master and the ECM is slave. using SY/TY ecm and code will not be recognized by the Vette's CCM

doug_dayson

Right, it would be running the $58 Sy/Ty Code, whick I've learned will also run on the Vette's 727 ECM with a minor repinning...

Hmmm, I believe the CCM needs VSS (for the radio's auto gain control), as does the FX3 Computer (for shock valving).

Thanks for the heads up!

I know a guy who's running a FAST, so I'll check with him and report back.

Thanks again...

Doug

-=Jeff=-

Yes the CCM uses the vettes VSS, but the VSS feeds direct into the CCM so you would get a SYS code just stating that the CCM and ECM are not communicating, but the SCV on the radio and FX3 will still work.

doug_dayson

krivera

i am saving up money to go and get my syclone computer and do some repinning and see what happens! i dont think there is a vette on this forum that has done it yet? But if so i would like to have them speak up? If not i guess i will be the first when i get all my parts and stuff?

doug_dayson

Any reason you're not just going to run the $58 Sy/Ty Code on your current 727 ECM?

From Clint: The 749 is missing one quad driver and has an extra injector driver. Because of that you'll loose your AIR diverter valve and canister purge control functionality. Also there is an error in the egr math when you switch the
$58 code to 8 cylinder. You can leave it all on there to pass visual
inspection if they test emissions there it just won't work. I've personally
swapped between my stock 730ecm and a 749ecm both running the $58 code and
wired up as a sy/ty and they both run great. I know the 727 has the
weatherpack connectors going into the ecm compared to my 730, is there any
easy way to just pop the wires out of the connector and repin them? If so
that is what I would do. I know GM makes a couple pick looking tools that
allow you to remove the wire from the connector without cutting it.

...and Tom had an idea regarding building a short conversion harness, which would not require you to modify your car, and allow you to plug the original stuff back in at any time
etc...

From Tom: You can make an interface harness pretty easy. One way is to get a 730 core ECM, desolder the connectors from it so that you can plug in your harness connectors direct. Then get a set of 727 ECM harness connectors from a junk F body harness, as I believe the connectors are the same as the 749 then make up the interconnects between the 730 header plug and your scabbed junk yard 727 ECM connectors, all of the crossover is done in your new harness and would be a plug in fit.

NOTE: Clint has done this in his F-Body, but there are a couple of other issues with Vette's...

a) Losing Cannister Purge functionality will require you to vent your gas cap.
b) The Vette's CCM will not acknowledge the 749, or the 727 running the $58 Code, so the warning light will always be flashing, but everything should work.

I'd suggest making a short conversion harness, and just running the Sy/Ty $58 Code on your current 727 as the easiest, and cheapest solution...

Good luck...

Doug