pcmhacking.net

I'm not sure whether or not it's possible to change the firing order, such as in your example from 18726543 to 13421342, and that's not the way I envisaged it. Using your firing orders I would wire up the coil & injectors as follows:

1 => 1
8 => nothing
7 => 3
2 => nothing
6 => 4
5 => nothing
4 => 2
3 => nothing

and then disable DTCs & fault flags for 8, 2, 5 & 3.

By your logic, if it works as I'd imagine it, each cylinder will receive a spark during the exhaust stroke which won't make a stick of difference such as in all wasted spark systems but it would also get a shot of fuel during the exhaust stroke & I'd imagine that would produce somewhat unwanted results.

From the small bit of research I have done looking into this it should be possible to wire up the coils & injectors as I have stipulated above, as well as disable the DTCs & fault flags for the missing cylinders and simply work assuming you provide it with the correct crank & cam position signals.

Then comes the sticky bit as mentioned by antus earlier:

antus wrote:It would take a quite a bit of tuning, as it'd be set up for the amount of air and advance a v8 is expecting, and thats probably the biggest reason people dont do it. There are a lot of tables in those PCMs, and its a lot easier to start off with a pretty close platform and not need to change most the calibration. Moving to a 4cyl would be more work after you got the hardware working.

But, if you could get correct data into those tables then any custom/programmable V8 binary will work once the DTCs, flags and tables have been set accordingly.

Well, that's the way I see it, but I'm no expert.

Chuff

I think the extra fuel pulse would happen during the combustion stroke, which ought to work just fine. I'd expect it to work better than throttle-body injection, for example... And way better than carburetors!

You'd just have to tell the PCM that the injectors flow twice as much as they actually do, so that it will cut the pulse times in half.

I think it's worth a try. If problems come up, I bet we can find ways around them.

PO1 4cyl testing

This is what I'm working on.
viewtopic.php?f=42&t=7810&p=116204#p116204

Yortt wrote:PO1 4cyl testing

RIMG0667.JPG

RIMG0661.JPG

That looks like it'll be fun.
Tell me about your setup/programming.

Thorwon wrote:

Yortt wrote:PO1 4cyl testing

RIMG0667.JPG

RIMG0661.JPG

That looks like it'll be fun.
Tell me about your setup/programming.

My setup/programing was initiated after Dick at Dick's Electronics was progressing his conversion project on a 4 cylinder turbo Toyota we both have the cars running and drivable now but still require work sorting out fine tuning. Dick is using his RTLS1 hardware/software and operating system which is different to me. I am using HP Tuners with the 1290005 operating system on my turbo 4 cylinder engine. The start tune was sourced from my son's LS1 turbo running a developed E85 tune the PCM thinks it is running a V8 engine with appropriately connected coils and injectors to the 4 cylinder engine. So does it work YES, can the fine tuning be sorted out, time will tell.