could anybody tell me how far the s4 afm opens during idle and starting?

 

the actual angle of the door?

voltage is 5v with KOEO

not much during starting, ECU ignores the signal during cranking

at idle i dunno, voltage is about 2.25-2.5

AFM is fully open (depending on mods) by 5000/6000, voltage is 0

if you're into that kind of thing, the afm is pretty adjustable

 

it seems that it will only start with me pushing the flapper door open a little bit

thats why i ask

thanks j9fd3s for the info

 

you might have a vacuum leak somewhere. Check all your vacuum lines and intake manifold gaskets.

 

A small amount of air bypasses the afm. Even with the flapper all the way closed. The bypass is built into the body of the afm. Excluding the bypass, even when the flapper door is closed, unlike a throttle plate, it isn't 100% air tight.

 

the fuel pump comes on when there is a start signal from the ECU (cranking) and when the AFM is open some (running)

 

IF somebody has bypassed the stock electrical starting circuit, then when you hold the key to START, the circuit opening relay won't get a signal and won't cause the fuel pump to work.

IF the above is true, that would explain why the engine starts if the vane in the afm is pushed aft a touch. You make a small switch when you move the vane aft (1/8" or so) and that switch causes the circuit opening relay to pull in and power the fuel pump.

Then again.....it could be another thing.

One way to prove the above TRUE or false, is to pull the trigger wire off the starter solenoid. The HOLD the key to START. The fuel pump should run as long as the key is HELD to START. Listen for it. Takes but a moment to do this. Just reach under the car.....feel for the starter....feel for the small wire......pull it offf.........do the above.

 

i was hoping we'd be putting an LED on the fuel pump wires! the LED on the o2 sensor plug is genius BTW.

 

Most all the posts above have a good answer as to why the thing won't run. You have to figure out which one is the problem though.

Could be a big *** air leak so the vane in the afm won't move aft to make the internal fuel switch in the seires four afm.

HEY I HAVE AN ANSWER FOR YOUR ORIGINAL QUESTION. THE vane has to move aft enough to CLOSE the fuel switch in the afm constantly. How far is that? Put the key to ON and push the vane aft slowly. When you hear the fuel pump start to run............measure how far you pushed the vane aft. That distance is the minimal distance the vane has to move aft for the car to keep running. Ain't far a'tall.

Not very far at all. That's why a big *** air leak in the ducting b/t the afm and throttle housing could cause the afm not to move enough aft to CLOSE the fuel switch inside the afm.

 

thanks for all the replys.
i already hardwired the fuel pump, it is on with key switch
and the tps is in spec of the fsm 4k ohm +/-5

 

so does the ecu get a "start" signal?

 

that is a good question! i will look at that

if it is not getting that signal, would it not be delivering fuel as needed?