Will the express van OS run indicidual coil packs, or are you back to running a dizzy?

 

I'm not convinced we can dump the opti (dizzy) anyway. We still need a "24X" signal from somewhere for the LS1 PCM. The opti provides two signals, a "360X" signal (high resolution), and a low resolution (don't know off the top of my head what it is). So putting a "pulse conversion" module in between the opti and the PCM that fires one pulse to the PCM for every 15 pulses from the opti would give the PCM the input it requires.

As for the coil setup, this could be an end-user option. If the customer wanted separate coils and they hooked them up this way, the only purpose the opti is serving at this point is to provide the 24X signal. If they wanted to retain the single-coil setup of the LT1, electronically we'd run all the coil outputs together through diodes into the LT1 coil, and this should work fine, also.

The gauge issue listed a couple posts back is not an issue on LT1 cars because the gauge inputs come from sensors directly, and are not routed through the PCM. I'm fairly certain all that would need to be done to make this work is to have the opti pulse converter, and an adapter harness that essentially converts from the LT1 PCM connector to the LS1 PCM connector.

This is a very exciting project!

 

You could, but you would need the OBDII timing cover and crank position sensor. It's 4x and you could condition that as needed. I'd just keep the opti, though, so I don't have to change any hard parts.

The low res is 4x, but the pulses are not equal in duration.

The Tach and Speedo are both controlled by the LT1 ECM.

Mike

 

Yeah, I like the opti solution, too, because I have an OBD1 LT1. LOL.

Good points on the speedo and tach. Now I see why this is could be a challenge. LS1 cars have an instrument cluster driven by OBD2 data.

However, it might be OK.

There is a separate tach output signal from the PCM (pin 10, RED connector).

There is also a 4000 pulses per mile output on the LS1 PCM used for the cruise control (pin 50, RED connector).

Yes, one of the work items for this project would be to verify whether the signalling is compatible.

 

I know this is a somewhat old thread, but only a month or so. I was sent an email about an LT1 in a 96 tahoe, but doesnt want to do alot of wiring. I suggested using an intake from www.lt1intake.com (just dizzy hole, no water passage conversion) and use the crab style distributor, and re wire the vortec harness injector connectors to go to the LT1's injectors.

This approach completely does away with the Opti-Spark. Of course you'd have to have a 96+ LT1 with crank sensor in timing cover.

This should seem a logical easy thing to do with the guys running 411 code from express vans. I think you could get the distributor to fit in the 4th Gen cars too.

Anyone got any input on this approach?

 

Most people won't want to tun a distributor in a 4th gen.

 

I'm considering this or a megasquirt. Som its time to come back to life.

This will be a solid roller, storker turning 7500-8000.

 

No, the 01-02 Express van engine uses the 96-99 Vortec (L31) crank and cam signals. Let's not get this confused with the LT1 crank signal that is NOT compatible with the 411 PCM.

Coil packs could be used if the LS1 crank signal were being used...and the LS1 uses an uneven pulse (a pattern) where the vortec engine uses an even four pulse signal.

There is no easy way to build a conversion harness for the LT1 due to there being no mating connector to the LT1 PCM connectors (among other hurdles)...however a complete engine harness could be built...when someone tackles the cam/crank signal issue.

EFI Connection might be willing to consider building such a harness once the cam/crank signal issue is resolved. Until then, we're building 411 conversion harnesses for gen 1 engines only.

Mike
EFI Connection

 

Seems like all you would have to do is make a new optical wheel, with slots to emulate the 1X LS1 cam sensor signal and the 24X LS1 crank sensor signal.

 

I started going down that road. The LS1 reluctor is an uneven pulse. Remaking the wheel would be a great challenge.

 

Cutting the wheel would be difficult, but someone has to be making them for Mitsubishi.

The alternative would be an add-on wheel in front of the damper, that could be cut to match the LS1 crank wheel. Something like E'motive makes, but with the specific pattern of the LS1.

http://members.aol.com/InjuneerZZ/im...otos/sdi01.jpg

Then there's the MSD distributor plug, that they used for their CPC system.... and an interface to that.

http://www.msdignition.com/np2002/images/pn7600_big.jpg

 

I think I may be able to weld some alumiinim to the stock LT1 timing cover and machine it to hold the vortec crank positon sensor. I'm going to try to locate all the parts and see what I can do at work. I have access to a 4.3L vortec v-6 if that will give me the dimensions I need to locate the crank sensor. I just need the right reluctor wheel.

 

Security isnt an issue, you just turn it off in the PCM..

 

Any progress on this? This could be great for the LT1 community. Ignition is one of our handicaps

 

Again?