2.3L ('83-'97) 1990 2.3 5-Speed 2wd Ranger won't idle

[LurkerMike]

1990 2.3 5-Speed 2wd Ranger won't idle
Very hard start with throttle 1/2 way open
Starts fine on starting fluid
Won't idle unless throttle used to keep idle above 1100 rpms
New:
Fuel Pump
Fuel Filter
Fuel pressure regulator
Fuel injectors
TPS
MAF
Spark plugs and wires
EGR inspected, not stuck open
Intake vacuum leak not detected with smoke test
New ECM/PCM ordered

Any ideas would be greatly appreciated as throwing money and parts at it has left me broke. It's still a one-owner with around 200k miles and has been a good ole girl survivor until I let it sit 2 years. Fresh gas and some Berryman's made no difference. Thanks

 

[SenorNoob]

Was the tank drained then fresh gas? Or just added to what was in there? That usually just results in a full tank of bad gas...

 

[LurkerMike]

Was the tank drained then fresh gas? Or just added to what was in there? That usually just results in a full tank of bad gas...

Thanks, there was maybe 4 gallons of ~year old ethanol free gas that had stabil added when filled. I added 5 gallons of fresh ethanol free and a can of berrymans with zero change. If there had been even the slightest improvement, I would have drained the tank and started fresh. The fact the truck will run at part throttle and WOT, make me think the gas isn't the main problem. It has the slightest stumble sometimes when reved to WOT before it warms up.

I should have noted my scanner won't connect to the ECM/PCM. But that makes no sense as there is no check engine light, and how does it run at all with a bad ECM/PCM?

 

[SenorNoob]

Sounds like you should be good on the gas front then. Tried a propane torch (unlit) around the intake to see if that makes any changes? Smoke test should've caught that tho... How's the wiring look mice/squirrels nest anywhere? Starts fine with starting fluid sounds like there is too much air or not enough fuel? What is the fuel pressure?

 

[LurkerMike]

Wiring looks good, no rodent signs. I think the fuel pressure is around 25psi, same as the fuel pump that was replaced. I agree, too little fuel or too much air. Which make me think now to check the throttle plate to make sure it is closing all the way.

 

[scotts90ranger]

You only have control of the air valve (throttle), it is supposed to meter the fuel according to preset tables and oxygen sensor feedback to meet the amount of air you are getting it based on engine speed and data from mostly the MAF with some input from the air temperature sensor and coolant temperature sensor.

I need to get to bed so not reading up at this time of night but do you have any trouble codes? Unfortunately hooking it to a scanner isn't really easy like an OBD II would be.

I think the MAF is 3 or 4 wires, I would check continuity from one end to the other and possibly voltage at the sensor end. do NOT stab the wire insulation to test, unplug and check at the terminals of the connectors...

 

[LurkerMike]

It looks like the ECM/PCM is the main culprit. Swapped a different part number ECM/PCM in and it starts but idle is off. Sending original unit off for rebuild or will order correct ECM/PCM.

Again, no check engine light and won't communicate with scanner. I hope this helps someone else in the future to avoid throwing unneeded parts at this kind of problem.