sssalah

Been thinking about the possibility of using an LS1 pcm on the LT1. I’ve worked with HP tuners and the LS1 pcm is much more than the LT1. One of the main reasons people go with aftermarket computers is the higher rpm capability, the LS1 is capable of 8k rpm and can be had for much cheaper.
The only obstacle I see is the signal from the camshaft sensor on the LS1, but this can could be had maybe through a converter from the opti sensor.

engineermike

Craig Moates (www.moates.net) and Geoff Skinner (www.thunderracing.com) were trying to talk me into doing this to my car the other day. The LS1 ECM will do 3 bar Speed Density also.

It can be done, but you need a wizard like Craig to figure the pinouts and wiring. I believe you would have to switch over to a '96/'97 timing chain cover and use the crank position sensor as the pickup, doing away with the optical pickup totally. You might have to switch to indivicual coils also.

Mike

sssalah

I'm already running the LTCC with LS1 coils. Also have the cloyes double roller timing set which will have to be changed to single roller to make space for the reluctor.
Getting rid of the opti is a win win situation, and I came to know that the 4-7 cam swap would be easier.
I'll eventually go with a solid roller and a single plane and so the LS1 PCM should be much better suited to high rpm and a big single blade TB.
Thanks for the references Mike.

VinceTrifecta

This is a very interesting idea.

The LS1 has both a cam and crank sensor, the former being essentially equivalent to the high resolution pickup in the opti. I believe in the LS1, like the LT1, the crank sensor is used for misfire detection and the cam sensor is used for ignition timing.

So, you'd probably have to retain both sensors to use the LS1 PCM in an LT1 application (or at the very least, the cam sensor).

As engineermike points out, the ignition coil setup is an issue as well. If you weren't opposed to retaining the whole opti, you could electronically "OR" (using diodes, perhaps) the 8 ignition outputs from the PCM into a single coil, and use the opti as the distributor.

The knock sensors are different on the LS1 and would have to dealt with appropriately.

If the car was an A4, that should connect right up provided it is a 1995 or newer 4L60E with TCC PWM.

And, of course, you'd need a shrewd PCM programmer to make the whole setup work.

engineermike

So far, the biggest obstacle I see is getting the proper crank/cam reference signals to the ECM. You might be able to use the high-res opti as the cam sensor signal and you might be able to use the crank pos sensor for the crank pos input, but you might not have the right number of pulses per cycle in either case.

Ever consider MegaSquirt?

Alvin@pcmforless.com

Craig ought to come up with a interface to do such a job. he'd make a killing and I'd be glad to take a cut for giving him the idea.

I'd much rather use a LS1 type PCM than a megasquirt. But both are better than the stock LT1 PCM.

Mkos1980

I am accually using the 411 LS ECM on my 89 Formula and 89 RS. I am using a Vortec motor timing chain cover with the provision for the crank sensor. Also, my Vortec dis crab style has a cam sensor in it. I did have to convert to a single roller and also get my balance snout machine down 1/8 to make space in bewtween the ring and snout. As for getting the crank and cam in sync, We just had to do a basic crank relearn procedure. I had to use a 96 and up vortec coil, ignition module and 2 4 wire 02's . I had the partial harness built by my friend at EFIConnection.com and are using EFILive for tuning. Drivability and tuning has been a breeze.

trax

Without knowing much about the way that the LS1 PCM is set up, I would bet that the easiest way to get it running would be to use some kind of crank trigger setup. Wouldn't the difference in the number of teeth on the LT1 crank reluctor wheel cause issues otherwise?

Mkos1980

No, because you can load in a file from an 01 Express van as a starting point which utilized the LT1 crank ring and its crank sensor. They used the 411 Ecm on those motors which were still a Gen 1 motor. You can accually use any crank sensor from a 96 and up vortec motor.

trax

So the Express vans are basically an LS1-era PCM on a Gen 1 motor with an LT1 crank position sensor?

Sorry if I'm not following... I don't know much about what PCM's were available after the LT1 came out.

Mkos1980

Correct. The LS1 ecm also came on certain Year Astro vans as well with the 4.3 When I converted from the Old 89 MAF 165 ecm to the 411, it was night and day differance. Also, you can delete the MAF portion of the 411 ECM and run a custom SD tune solo which I am doing. So far both of my cars are running flawless on this setup.

Tourque

Been a while... I forget.. . what are the max RPMs attainable via. LT-1 ECM vs. LS-1 ECM? Do OBDII LT-1 ECM's have a higher RPM range? Been 3 or 4yrs since I looked into this. Intersted to see what has changed.

CALL911

If anyone were to make this available as a complete kit to change the LT1 PCM for an LS1 one, including everything needed such as directions and the LS1 coil packs ect, they would make a KILLING! I know it would require a bit of work, but there is a HUGE market for such a thing! Someone should seriously do this!!

engineermike

I sat and talked with moates for about an hour yesterday about this. He wants to build an interface box that would plug in between the opti pickup and the ECM to process the signal such that it's LS1 ECM compatible. Then, the biggest hurdle would be wiring up to the correct pins on the ECM. Finally, you would have to muddle through all the gauge calibrations, HVAC controls, security stuff, transmission stuff, etc. . . There's alot of work to be done.

Mike

CALL911

Agreed, much time and work would be required for this, however the pay off for someone who successfully completes a plug and play kit for sale to the public would be a great success for both the manufacturer and the public.