I'm troubleshooting a no start / repeat flooding issue.
I have compression & spark & 12V @ injector ecu pins.

My question is when I'm turning the car over to start it, what should the duty cycle be on my injectors? More specifically what should I see on my multimeter at the ecu pins?

And what should duty cycle be at idle?

Thanks guys

 

On my Power FC duty cycle at 850 idle reads about 3.5-4.5% if I remember right. Hope that helps. I dont remember the injector duty cycle on cranking but can check if you need me to. These are with stock 550cc primaries.

 

So when you say 3.5-4.5%, that's a % of 12V, so you'd see approx 0.5 volts at the primary pins at idle?

I would be interested in your cranking duty cycle if it's easy enough to get.

Thanks again

 

I'm actually not reading the voltage directly off the ECU pin. I'm reading off the PFC commander (like how all the FD guys) do through the PFC. When I go move my car during lunch I'll see if it reads the duty cycle during cranking.

 

*********So when you say 3.5-4.5%, that's a % of 12V, so you'd see approx 0.5 volts at the primary pins at idle? ***************

Just the opposite. You would start with a voltage of somewhere around 12vdc plus on the injector before you crank the engine and as you crank the voltage would drop to the high elevens (guess).

 

Checked injector duty during cranking and it started out at 3-4% then jumped to 9-10% right when itactually started (all within a second or 2). Then proceeded to drop back to 3-4% at idle with a warm engine.

I should also mention there are automatic fuel map corrections based on air temp and water temp but I'm in SF, CA and it's pretty mild weather for the most part.

 

injector PULSES
not hold open the valve according to the voltage

3% means it applys 12V for 3% of the time.

 

I'd use a digital storage oscilliscope and check the injector pulsewidth and wave pattern.

 

There's a number of digital volt meters out there that will measure duty cycle. Just tap into the fuel injector wire at the ECU and it'll register the duty cycle. I even saw one at Radio Shack a couple of years ago that had that feature. Fairly cheap if I remember right. Or you could buy a used Fluke88 automobile meter off E-Bay or??? Not as cheap but out there somewhere.

When you really get on the pedal the voltage drop will be in the five volts or less range. Yo I know duty cycle is shown in percent but the voltage drop is interesting also.

 

Hmmm...how does it know duty cycle when there's no reference to engine RPM's?


-Ted

 

http://assets.fluke.com/admintools/m...pplement=false

 

Who is this question directed towards?

 

I think he was asking HAILERS.

The original question was what should I see on a multi-meter at the ecu primary injector pins at start up and idle.

My car seems to be dumping an aweful lot of fuel for no apparent reason. So much so that it won't run and continues to flood itself.

 

Leaking/sticking injectors maybe?

 

1 injector pulse.....one crank revolution.

 

RPM doesn't matter for duty cycle calculations. On for 1ms, off for 9ms = 10% duty cycle. You just measure the on & off time, divide the on time by the total time for the cycle, and display the percentage.

-=Russ=-