Re: 92 LT5 ecu ignition program and control
 

I dont know what a fsm is .
The whole engine electronics system I have including all sensors ecm etc etc so , if the ignition will fire and run its timing control without the fuel injection side of things operational im hopeful it will work with carbys . Dont know if its possible though .

Re: 92 LT5 ecu ignition program and control
 

FSM=Factory Service Manual.
WVZR-1 has it on PDF, or you can probably find a copy on eBay.

Re: 92 LT5 ecu ignition program and control
 

I have bought the books on ebay and am expecting them to arrive in a week or so . I bought them to help me try and decipher the ecm's operation.

Re: 92 LT5 ecu ignition program and control
 

The ignition module works like most any other GM HEI module. The ECM is connected w the same 4 wires as other modules + a DIS Fault line. The crank provides the firing signal w the ECM controlling Spark Advance. No cam signal is used for ignition, just for sequencing the injectors which are managed by the ECM.
Which brings up a point about your carb setup. You will need to shutoff the injector bosses in the Injector Housings. With carbs, you won't be using 43# of fuel pressure either.
Given that you are not communicating w a CCM, you could consider some other Engine Control Management rather than the stock ECM so as to utilize an LS based ignition w a reluctor wheel on the crank nose. Someone just recently did that I believe using a Holley setup.

Re: 92 LT5 ecu ignition program and control
 

Here’s a thought for you.... rather than using carbs you can achieve the same look with one of the new carb replacement systems like the Holley Super EFI. In turn tuning and performance are optimized. It uses the 4 wire system Dominic mentioned, has a built in ECU and is self tuning.
H
:cheers:

Re: 92 LT5 ecu ignition program and control
 

I have looked into a MSD 6010 box with a front mouted trigger on the nose of the crank . 6010 are for ls1 motors and I think I can use one but would just need to alter the coil triggering wire sequence to match the lt5 firing order and fit coil mount brackets for the ls coils .
Done maths on it and would be around $2000 au dollars .
Thats what led me to looking at using the original ignition system if possible .
Big advantage with the msd box though is user friendly timing setup . Plug in your computer and plot your own curve .

Re: 92 LT5 ecu ignition program and control
 

To be accurate, u can plot any ignition curve u want using the stock ECM.

Re: 92 LT5 ecu ignition program and control
 

To plot an adjusted ignition curve on stock ecm with carbys fitted I gues Id need a dyno run and someone who can program the chip . Is the chip programming capable of being done by any dyno company or are lt5s requiring specialists ?

Re: 92 LT5 ecu ignition program and control
 

Spark tuning is spark tuning. What’s needed is someone who knows their way around the LT5 calibration. If u r looking for part throttle, then an engine dyno or driving the car around and datalogging is how u get there. There are stock spark
tables to start with.
I use a dyno for WOT tuning and after I have the driveability down first.
Other than the carbs, what else do u plan on modifying?

Re: 92 LT5 ecu ignition program and control
 

I dont plan on modifying any internals . Only mods will be removal of the secondaries and pluging injector bosses and other vacuum ports etcetc.
I may look at removing the injector boss material from inside the port . Will look closer at that option once I get a good look at what material would need to be removed . Looking down the ports though I see a fair flow obstruction that may benefit performance if I can smooth them .
Also has custom headers.