Hi All,

I'm having an issue where when I start my 97 Ford Ranger 4.0 OHV from cold it will run for a few seconds and then die. I start it right back up and it’s fine but it’s now progressed to the point it has started cutting out while I’m driving and place my foot on the clutch. It isn’t frequent but is becoming more common and I’m looking to get to the bottom of it.

Essentially when i place my foot my foot on the clutch I see the engine oil pressure flicker and then the engine dies. As I’m still moving if I release he clutch it jump starts the engine and continues as normal. It’s absolutely fine when driving in gear and has zero issues otherwise.

I have caught it almost cutting out a few times and if I give it some gas it revs up and sorts itself.

My initial (uneducated) opinion points me to the Idle Control Valve but wondered if anyone else had any ideas/suggestions to try first?

Thanks
Scott

 

Flicker oil pressure needle would indicate electrical issue.

To see if IAC Valve and computer are working, cold start should be like this
Key on
computer boots up and opens IAC Valve all the way for starting
Engine starts and RPMs should go high, 1,400+, IAC Valve is open all the way
Then immediately after starting RPMs will drop to about 1,100, cold engine target RPMs, from computer closing IAC Valve a bit
As engine warms up computer continues to close IAC Valve until warm engine target idle is reached, on manual trans that should be about 650rpm, although emissions standards may make it higher in 1997

If your cold starts are not going to high RPMs, "Choke mode" then could be ECT issue
Cold or warm engine is set by ECT(engine coolant temp) sensor data going to computer.
Your engine will have TWO ECT units, a sensor and a SENDER, sender is used only by dash board temp gauge
Sensor is used only by computer and will have Grey/red and Green/red wires
Sender is usually only a 1 wire unit, red/white

You can test ECT sensors but they are not expensive to replace

If RPMs don't seems to be changing at all then Clean and test IAC Valve
Cold engine
Remove IAC Valve, connect it wires
Turn key on
IAC Valve should now be open all the way
Unplug the two wires, it should close all the way
Plug wires back in and it should open all the way
repeat as much as needed to determine it is working and not sticking

IAC Valve is a 12volt solenoid with a spring and valve
It gets 12volts with key on and Computer controls it's ground wire
With 12volts and full ground solenoid pulls open valve all the way against the spring pressure
Computer "Pulses" the Ground which in-effect lowers the voltage so spring pressure pushes valve closed a bit as voltage is lessened
Simple system but still a "moving part" so can wear out

Vacuum leak test
After engine is fully warmed up and idling
Unplug 2 wires on IAC Valve
RPMs should drop to 500 or engine may stall, either is good it means no vacuum leaks
In your case I doubt there is a vacuum leak or engine would not stall
But still a good free test to know about

 

Thanks Ron, this gives me a lot to go on for cold starts, but would this be related to the engine cutting out while it is driving at normal operating temperature when I press the clutch occasionally? I just suspected the two were linked.