225 odd fire fuel injection

I know that this has been discussed numerous times and is currently being discussed in another thread, but I want feedback on a different approach.

I believe that the main problem with setting up fuel injection on an odd fire is trying to use a v-6 fuel injection. The odd fire v-6 is a v-8 minus 2 firing position. Would it make sense then to use a v-8 setup, possibly sfi or mpi and overlay the v-8 timing order with the v-6 order including the gaps. This would give you the order to hook up the injectors. This would allow the injectors to fire at the proper time. With a tbi setup it would be possible to have a custom chip burnt to omit the two pules that the v-6 doesn't have as not to foul out the 2 cylinders that fire after the gap.

Just thinking about this type of a setup and was wanting some other input.

 

Forget about any of the V8 stuff or reburning chips. Either bolt on a ProJection kit or get a 4.3 V6 setup and use a Holley crank trigger for an RPM signal to the PCM. A guy near me even went so far as to modify his stock harmonic balancer to provide an evenly pulsed RPM signal but I think it would be easier to go the Holley route (~$250 from Summit or Jegs) unless you live in Mcruff's house.

 

I would have to agree. I have had really good luck with the Holley kit. It works just fine with the 225 other than the overly rich condition when getting past 95% into the throttle. Anything other than the Pro-Jection, in my opinion, would be a waste of time and $ on the 225.
If I had it to do over again I would have kept the Vortec 4.3 I scrounged this summer to swap in. I don't mind the 225, it has gobs of torque, I just want the smooth as glass idle of a Vortec V6. Being a mechanic by day, the odd idle of the 225 always makes me miss the even fire Injected motors. No bumty bumpty idle and no adjustments to worry about.

 

I have the older analog Pro jection on my 4.3 and it runs great. I was concerned about runability as well, since it's designed for a "V8". Even Holley tech support said it wouldn't work, but it does. You can even buy different flow rate injectors to fine tune it. I have 80 pph ones in now. they are a bit rich, but I can deal with it. I think the newer Holley setups are laptop programmable as far as fuel curve goes too.

 

There seems to be much agonizing over getting sequential fuel injection to work properly with the odd fire V-6.

Does it really matter? Information on the megasquirt site seems to indicate that sequential offers very slight efficiency and emmisions improvement, primarily at idle, over batch or bank to bank injection.

Batch and bank to bank injection are much easier to implement.

I haven't started yet, but my plan would be to use a megasquire ecm and go with bank to bank injection.

Lots of good information on megasquirt and motec websites. Of course motec tout the advantages of sequential injection and their $1500+ ecm over bank to bank and the megasquirt ecm for under $300.

 

I'm skipping the MFI, SFI, TBI, EIEIO discussion today

EDIT: but then again...

I was just thinking after reading comments above. It the previous thread I had a theory that a 1984 FI system might bolt up to a 225. Duh --even fire SFI sequencing on odd fire crank throws --won't work .

Back to the drawing board

 

So you have a Pro-jection kit on your 225? And it works?

I have more questions if it is true.

Scott

 

Yes the Pro-Jection works fine on my 225. In fact I even drove it to work today!
I did notice a new problem though. I left my CJ running this morning to warm up and it was loading up when I came back outside. One hit of the gas and it cleared right up. Guess I've got some more fiddling to do with the knobs.

 

My 231 odd-fire runs on a 1991 4.3 Chevy V6 TBI unit---Holley Crank sensor triggers the injectors through an ignition module that talks to the main computer. The TBI was and computer was taken from a 1991 Chevy Astro Van.
Custom burnt chip from Affordable Fuel injection. It is a closed system with a MAP and O2 sensor (Coolant heat sensor too). It is adapted to the stock intake manifold with home build adapter.

It also loads once between open and closed system transitions as the engine heats-up.

It was running in a Nissan Truck-- but now is mounted in my CJ6 project (far from running again.

Such a system could be run without an O2 sensor or MAP too--- just using the Crank Sensor.


So there are several ways to do fuel injection to an odd-fire.

 

How is the projection kit getting the ignition signal? Crank trigger?

Thanks
Scott

 

Tach signal. Nickmil.

 

I think Steverdenver has the set up! That 4.3 TBI is great simple system. I've always felt that this TBI and a friend with a CNC machine would make for a good Buick conversion.

I assume you run all the stock 4.3 sensors -- Baro, TPS, etc etc

 

How can it run off of the tach signal? Isn't the tach signal an unevenly spaced signal like the ignition?

Scott

 

The Holley ECM uses the tach signal to fire the injectors and keep track of the RPM. It doesn't control anything except spark, so there is no differance whether it's odd or even fire. Works just fine for me whether it's supposed to or not.

 

It doesn't matter when the injectors fire. The injectors do not have to fire the exact time of intake valve opening to offer the advantages of multiport injection over throttle body.

The main advantages of port injection over throttle body are related to improved intake manifold design, better fuel atomization and, the proximity of the injector to the intake port. These advantages remain even if the injector fires at other than in perfect sequence with the intake timing.

Think about how many intake strokes occur even at a high idle of 1000 rpm - 500 intake strokes per minute, 8.3 intake strokes per second, one stroke every 1/8 of a second.

OEM manufacturers are very driven to push every ounce of efficiency out of their efi systems - they have to meet ever increasing mpg and emmisions goals in order to meet governmental goals, to effectively sell vehicles.

Bottom line is - multiport injection does not need to be synced to engine timing to work! Adapting an even fire system to our odd fire engines should be workable.

 

Craig,

You are correct, but the problem with using the tach signal from an odd fire is that the signal is not spaced evenly. Because of this the ECM constantly tries to adjust the RPMs. This is why Steve used a crank trigger to get an evenly spaced signal that the ECM could use.