RX200013B

what or how is the best way to test for injector pulse, i dont seem to have any

86 s4 n/a

i have spark and fuel pressure, no injector pulse

pfsantos

iTrader: (1)

You can use a mechanics stethospcope on the injectors to hear for clicking. The secondaries don't fire up until you have engine load and around 3500RPM's though, so keep that in mind (the FSM shows how to test them at idle under no load).

A little more work (for the primary injectors), but you can unplug the injectors, put an LED (oriented correctly) across the two pins at the plug and look for blinking.

The last and probably best way is to find the right pins at the ECU under the pass. footwell, and see if the wires from the injectors are grounding in pulses, using an LED (which the ECU does to fire them). The injectors are fed power, the ECU grounds their circuits to fire them. See FSM for pin-outs of ECU.

edit: don't think you're looking for actual pulse length, for that you'd need an oscilloscope (sp?) or something.

RX200013B

what else to check if i dont have injector pulse , i was checking at the ecu

arghx

iTrader: (3)

plug a spare crank angle sensor into the plug (or remove the one you have if you don't have a spare). spin the CAS by hand and listen for clicking with the stethoscope.

RX200013B

i do have a spare

what about the afm?

fuel pump is hard wired

HAILERS2

Pull the white plugs off both lead and trail coil assy's. Attach the spare CAS to the harness. Key to ON. Spin the CAS. You should be able to hear the primarys click as you spin the CAS.

Or buy a single LED like the ones you use to set the TPS. The negative lead wire of the LED to either of the primary injectors. The other LED wire to the White/Blue wire on the left side of the small plug on your series four ECU.

Eveything connected up. All plugs connected up. Then turn the engine using the starter. The LED will blink each time it operates.

Primary wires on the small ECU plug are light green........and light green/black. The secondarys won't operate doing this.

Just spinning the SPARE CAS does it for me. Either way.

Also do this: STARE at the tach needle. Now while staring, turn the key to just ON. The tach needle should make one small bump. When it does that, the injectors also pulse. Been there, seen that using a LED. Primarys only.

RX200013B

and if i dont have a tick, where sould i go from there?

HAILERS2

Then you'd put the LED light on the wires as described. Before I did any of the above I'd check each light green wire in the small ECU plug for batt power (key to ON). The plug should stay connected to the ECU.

Also make sure the solenoid resistor package located below the airfilter/afm, is bolted to the fender and has it's large round plug on it.

A single LED as shown in the jpg in my other post would do the job if monitoring the light green or light green/black wire on the small plug of the ECU while spinning the starter (all elect plugs connected).

LED light cost a buck fifty at Radio Shack.

RX200013B

isnt the resister pack pos+ and the light green coming from the ecu neg-

HAILERS2

The solenoid resistor supplys power to one wire of fuel injector coil(s). Another wire leaves the fuel injector and goes to the ECU. THAT wire gets a ground pulsed on it by the ECU to make the injector work.

If a LED is used to visually watch the pulse of the injector, you find a source of constant battery voltage and connect the positive wire of the LED to that source. Then you attach the other wire of the LED to the light green wire (front primary injector wire). You can do this by backprobing the light green wire on the ECU plug. The plug must be left connected up to the ECU.

So you now turn the key to ON. The LED light stays off because it has batt voltage at both wires. NOW you spin the starter with the key to Start. The ECU will now pulse a ground to that wire of the LED and the light will blink on/off as the engine is rotated.

Personally, I have some degraded hearing from too many TF-30/F100229/F110-129/F220 etc and way too many rounds from a Colt 45 without hearing protection (one round was too many in my case). Meant to say if I remove the white plugs to the Trail and LEAD coils, and spin the CAS, even I can hear the primary fuel injectors pulse.

RX200013B

pulled pri injectors and replaced w/ diferent ones and she worked

thanks for all the advice