Using a 0411 PCM to run a TBI?

[turbo_bu]

I know this is very redneck, arguably, lazy way to do a setup, but it also has to do with what I have laying around. With all the fantastic work that has been done on LSDroid, I think the usability of the LS1 PCM could be further exploited. My theory is, that one could modify a TBI distributor to work as a crank sensor. I know you wouldn't have a cam sensor, but I don't think that you would need it either. As for injectors, my thought is to wire up 1 of the TBI's connected to half of the injectors, with the other TBI connected to the other half. Spark would be handled by using the old vortec engine distributor config (already an option in the LS OS).

Would this work? Please throw stones about things I haven't thought about. I have no problem with using all the existing tooling to scan and re-burn chips, but was hoping that this option might be more appealing to those with old TBI engines.

[dave w]

Your kinda late to the party.

Dual trigger (cam / crank) '0411 low resolution distributor.

EIGHT Injectors REQIRED!

dave w

Domestic V8_01.jpg

Domestic V8_02.jpg

[turbo_bu]

dave,

That looks pretty slick. Is there no way to keep the TBI injector setup? I know the performance of the TBI is not the greatest, but was hoping for a more "bolt on" setup. There was a guy over on the EFILive forum who rigged up a 0411 to run a 4 cylinder engine by not connecting 1/2 of the injectors. Believe he also just turned off the codes for those injectors, and it seemed to work.

[turbo_bu]

Looking at the TBI wiring diagrams, it looks like the very important crank sensor signal actual comes from the spark module. I think it is called "reference" on the TBI diagrams and comes in on pin B5. Does anyone know what this signal looks like? is it 5V? 12V? Square wave?

[dave w]

Looking at the TBI wiring diagrams, it looks like the very important crank sensor signal actual comes from the spark module. I think it is called "reference" on the TBI diagrams and comes in on pin B5. Does anyone know what this signal looks like? is it 5V? 12V? Square wave?

The attached picture is NOT a TBI computer! TBI computers use an identical ignition module system. The attached picture shows the ignition module converts the distributor pickup coil AC signal to a DC square wave. The voltage is likely less than 5 volts. The ECM is using the DC square wave FREQUENCY as a RPM reference.

gm-ign-module-schm.jpg

[turbo_bu]

dave w

Thanks for sharing that excellent diagram of whats going on with the ignition control module. I realize that it is not a TBI computer, but I am just hoping to figure out what signals are going into / coming out of the TBI ECM. If I can figure out what it uses, then maybe I can determine if there is a way to make a 0411 work with those existing signals.

The TBI reference signal looks very similar to what the crankshaft sensor would put out. The first question that comes to mind is voltage. The 0411 uses a 12 volt hall effect sensor for the CKP. The ignition module most likely is only kicking out a 5 V signal. I went ahead and fired up my 0411 bench PCM and modified my CKP signal from 12 volts to 5 volts. Lo and be hold, the PCM still was able to show a meaningful RPM signal when it was getting only a 5 V square wave! This is promising.

I guess the next thing is to figure out is what kind of signal a 0411 uses to control spark .... I kind of understand how it does the coil packs, but never looked into how it is used on the old 5.7 vortec engines with distributors. Did those engines still have some form of ignition control module? I know that they had actual crank and camshaft sensors.

[dave w]

dave,

That looks pretty slick. Is there no way to keep the TBI injector setup? I know the performance of the TBI is not the greatest, but was hoping for a more "bolt on" setup. There was a guy over on the EFILive forum who rigged up a 0411 to run a 4 cylinder engine by not connecting 1/2 of the injectors. Believe he also just turned off the codes for those injectors, and it seemed to work.

It might be possible to use the '0411 with TBI, but seem highly illogical to me. It might be more logical to replace the 2 injector TBI system with an 8 injector TPI / MPFI system using a "Bolt On" dual trigger distributor.

Perhaps the Learning Curve investment for LS Droid is better spend on an 8 injector TPI / MPFI system?

dave w