Should all the injectors be firing at the same time.

[240sxRAOR]

I have swaped a dohc ka24de into a Sohc body. It has never run well and had to go through alot of trial and error just to get it to idle and move. The car occaisonaly has intake backfires, random miss at idle and runs rich when you floor it to the point were the engine stalls. I decided to check out the components and one of the tests I tried was removing the fuel rail and cranking the engine to see if the injectors were firing well. All of them fired exactly at the same time, is that not suposed to happen? I can't find an answer to if that is normal. I'm hoping thats the problem cause if not I still have to keep looking and I'm really getting tired of this problem that noone can firgure out.

[PorkChopExpress]

depends some engines will batch fire 2 injectors at a time. not positive the ka does that

[240sxRAOR]

All 4 of them fire at the same time.

[carkook]

All 4 of them fire at the same time.

Can you explain this?

[240sxRAOR]

I had someone crank the engine over and watched the injectors fire. I was looking for iregular spraying and all seemed fine. All 4 injectors were firing at the exact same time. I thougt that injectors fire one at a time in a particular order like spark plugs. That just doesn't seem right to me and all I want to know is if its normal.

[carkook]

Yeah I would assume they should fire at different times, but I could be wrong. Now I want to know

[240sxRAOR]

I have worked as a mechanic for a year but don't have alot of this kind of experience. Its not normaly dealt with. My coworkers couldn't give me a strait answer either. Apperently some cars the injectors fire togather but with electronic control that doesn't make much sence. I could take my running car apart but I don't like finicking with a parts that are in order for they might break in the process. Of course if fireing all togather is the problem then the next question is. What can cause them to do that? I've eliminated the ECU.

[grecco28]

yes it does when you the engine is cold at the first start the inyector work twice every turn of the crankshaft(all) this is called simultaneous inyection,then when the engine reach his normal temperature change the mode to secuencial inyection (two cylinder at the same time) one time every turn of crankshaft...

[240sxRAOR]

Thanks man, so it wouldn't be the problem then. Looks like I'm going to have a feild day with the testing the sensors. Once again thanks for the help.

[tercel drifter]

no they should not fire at the same time. The explosion should happen right before piston tdc. as the pistons do not move at the same time, it makes no logical sense why the injectors be firing at the same time because some pistons will be at bdc as some will be at tdc

[the converted]

Nissan computers are set up so that when it sees any movement of the cas it will fire the injectors, then it will wait untill it gets a sync on where the engine is and fire individual injectors from there out. It's a strategy that most manufaturers use to start engines quicker.

[r3v_v3ng3]

I had someone crank the engine over and watched the injectors fire. I was looking for iregular spraying and all seemed fine. All 4 injectors were firing at the exact same time. I thougt that injectors fire one at a time in a particular order like spark plugs. That just doesn't seem right to me and all I want to know is if its normal.

the injectors fire so fast your naked eye won't tell the difference of the milisecond it took to go on and off but i don't they fire at the same time.

like someone above says it fires on tdc on waste spark ignition 2 cylinders fire at the same time. can't remember the details

[240sxRAOR]

Actualy the fireing is fast but at cranking speed you can see the firing order just like spark plugs with a timing light. Difference between all fireing togather and fireing in order can be seen at cranking speed.

[youngun21a]