Please, in the name of all that is good and decent, somebody please tell me what is wrong with my 1990 F150 with 300/E4OD. I been trying to figure it out for 2 years.
Here's a pretty good summary:

1) Stalls a lot when in gear and coming to a stop. Computer does not bump up the RPMs when put in gear. Idle air control valve does work. Computer does bump up cold idle speed & returns to normal idle after warmup. Idles too low in gear.

2) Starts hard cold. Cycling the fuel pump several times before cranking makes no difference. A shot of starting fluid & it starts right up. Starts fine when up to operating temperature. Fuel pressure 48 psi @ 20”, 52 psi @ 10”, 54 psi @ 0”.

3) Off idle surge.

No check engine lite. No codes. Passes KOEO and KOER test. Engine is mechanically sound. Acceptable oil pressure. Acceptable compression (1) 160 (2) 150 (3) 160 (4) 140 (5) 150 (6) 155

When I got the truck, the TPS and the EGR position sensor were bad. These have been repaired.

Temporarily blocked off the EGR valve: made no difference.

Tried several different good used parts: coil, ignition coil radio capacitor noise filter, IAT sensor and MAP sensor: made no difference.

Local repair shop replaced the coolant temperature sensor: made no difference and I already knew there was nothing wrong with the original sensor.

No vacuum leaks.

New ignition module. New distributor pickup. Distributor shaft and bushings are not worn. New idle air control valve. New cap, rotor, spark plugs, plug wires, fuel filter, air filter, PCV valve. Injectors cleaned twice. Gas is fresh. Under hood condition is (mostly) stock and unmolested. 3G upgrade.
Thank you.

 

Have the grounds ever been cleaned?

 

Interesting. Have you verified the computer is the correct one for the truck? You didn't mention any issues with the transmission but are there any? The E4OD should shift smoothly and at a comfortable RPM for every throttle position, it should not slam or require high rpms to shift.

What condition is the smog(air injection) equipment in? All original and functional? Does it have anything that sounds like an exhaust leak?

 

Have you used an ohm meter to check the closed throttle TPS voltage, and the linear voltage to wide open throttle?

The TPS can be installed with the rheostat catches behind the throttle shaft catch, and not advance the voltage.

 

Grounds: clean and present.

ECM: F0TF-KA Correct as far as I can tell. Nothing obviously burned up inside.

Transmission works great. Obviously has been rebuilt at some point because the shifts are slightly firm as they should be in a truck. Not a mushy slush box like Ford built them.

Smog pump and associated parts present, original, and working.

No exhaust leaks.

TPS is new and working correctly. It has a linear voltage output to wide open throttle.

I should also mention that any new parts I installed where of good quality, not Amazon no-name cheapies. New TPS is an Echlin that I bought about 16 years and never used. New idle air control valve is a Hitachi (same as Ford used). New distributor pickup is NTK/NGK. ETC.

Also inspected the vast majority of the engine harness and associated plugs.

 

Is it like hitachi as if hitachi only produces one line or is it hitachi like "AC delco" Silver which just means its an elevated low quality part(idk if hitachi does or not just dont assume its the quality of OE on that alone)

 

If it is the right computer then it sounds like a bad Manual Lever Position Sensor or its wiring going to the ECM Computer.

Edit:
You say it shifts OK so disregard the above.

 

I think it's Hitachi "good stuff" not Hitachi "cheap stuff". I'm trying to remember where I bought it so I can possibly check. The IAC does work, however, as it does take control of the cold idle RPM. Forgot to mention that the minimum idle speed screw has been adjusted per the manual.

Inspected the vast majority of the engine harness and associated plugs. No issues found.

This is just great! Wife and I have 3 vehicles. Two of them are currently fouled up and we both have to be at work on Monday.

 

Nissan service manuals say 'check the sensors, check the wires. If those are good, replace the computer.'
My '89 Mustang 5.0 had a weird quark where I would start it up in the morning and it would immediately stall. It would start up and idle perfectly after I restarted it. I changed out the ECU and it immediately fixed the problem.
Is there anything else on the truck that doesn't work? Thing like inop tail lights, or inop air-conditioning could be a hint.

 

Regardless if the PCM is good or bad, it is the correct one according to the number posted.

 

Talked to a mechanic yesterday. He was recommended by a different mechanic for being really good. He suggested everything I've already done. I brought up the computer, he said he doubts it's the problem. He's gonna look at the truck Saturday next week.

Everything else on the truck works.

 

Does the idle kick up when the ac compressor is on?

 

Just, offering thoughts.

The computer also adjusts timing, which will change idle speed. So, does the cold start high idle still happen if you pull the spout connector?

 

Truck built without A/C. Idle does kick up during cold starts.

 

I don't recall ever pulling the SPOUT connector while cold. When pulling SPOUT connector for setting timing, etc., engine should be at operating temperature.

I don't recall the exact procedure but there is a procedure for testing if the ECM has control of the timing. I did that test and it passed.