2.3L ('83-'97) Set timing without cam sensor

[Chapap]

Everything I’ve read says that it doesn’t matter if you have the intake or exhaust stroke identified because the valves determine that. It made sense to me but I never felt good about it. I finally realized why. How do the injectors know when to fire if you don’t have a cam sensor? If you’re off by half a cycle, they would be injecting on the power stroke instead of intake stroke… right? What would be symptoms of this?

 

[scotts90ranger]

On a batch fire system they calculate the amount of fuel needed to run and both fuel injectors (two pairs, 1 & 4 and 2 & 3 since they share TDC on a 4 cylinder, one on compression and one on exhaust stroke) fire at the same time. I don't remember how the intake valve timing works out but it does... It's slightly less efficient to run on batch fire but it works fine, especially for ignition...

 

[Chapap]

On a batch fire system they calculate the amount of fuel needed to run and both fuel injectors (two pairs, 1 & 4 and 2 & 3 since they share TDC on a 4 cylinder, one on compression and one on exhaust stroke) fire at the same time. I don't remember how the intake valve timing works out but it does... It's slightly less efficient to run on batch fire but it works fine, especially for ignition...

Interesting. I never would have thought that was done, but I guess it’s the only way to do it without a cam sensor. Since there’s half a dose of gas in the intake during the combustion stroke, could a leaky intake valve cause odd problems?

 

[RonD]

With a distributor sequential fuel injection is easy because a distributor IS a cam sensor

With distributorless systems sequential injection is still possible, after warm up, using power and efficiency from crank speed and O2 sensors
Computer has LITERALLY a 50/50 chance of getting it right just by guessing, lol, but if injector opens just when intake valve opens crank speed/power will be better and O2 will show better burn, vs slightly leaner if injector timing was on exhaust TDC, because more fuel stuck to intake/port walls
And that takes all of 2 seconds to do