Greetings,

I inherited a 1994 Ford Ranger 2WD with a 3.0L engine from my father when he passed away recently and I need some help. It seemed to work okay at first for starting up and taking a very short drive. But then I noticed that as soon as it starts getting warmed up it begins to stall, knock and eventually completely die if I continue to let it run. Once cooled off it would start again, then run again until completely warmed up, with knock and power loss getting more severe as I continued driving until it completely dies.

I've replaced the plugs, plug wires, MAF, Idle air control valve, throttle position sensor, distributor cap, rotor, coil, ICM, and engine coolant temperature sensor. None of that has changed anything in terms of performance.

I am going through the list of things left to try and have the following:

1) EGR valve does not appear to be present on this engine
2) PCV valve
3) Air filter
4) Fuel Filter
5) Crankshaft position sensor -- I believe that is part of the distributor cap that I replaced
6) Oxygen sensor - before catalytic convertor
7) Oxygen sensor - after catalytic convertor
8) Fuel pressure regulator
9) Thermostat
10) Air Intake Temperature sensor (already replaced as part of MAF)
11) Powertrain Control Module

Of these items, it seems that a defective camshaft position sensor might be the most likely culprit since it should be in a position to get very hot, but I'm not sure there is one on this year and model (with distributor) --- does anyone know if there is one (the auto parts store shows one but I'm not sure they're correct).

The other thing that seems most likely is the PCM

Would like to hear your thoughts on this

Thanks,

Jerry G

 

Sorry to read about your Father, condolences on your loss


Now Stop replacing stuff, lol
New parts are NEVER EVER TESTED now a days, so are worse than old parts because you "think" you have eliminated that cause because its a "new part", but you haven't
But most of the stuff was good to replace, its just the sensors that can be an issue as "new" is a roll of the dice

1991-1994 3.0l uses a distributor with TFI module, so no Cam sensor is needed, a distributor is a "cam sensor" since its driven by the Cam, distributorless engines(1995 and up 3.0l) got Cam Sensors, just FYI

Struggling to run after warm up was a common TFI issue on the 2.9l engines with TFI mounted on distributor, so 1991-1994 3.0l was changed to a Remote mounted TFI module, its away from the engine on the rad support to try and keep it running cooler, sill has a big heat sink around it

Because it has a distributor the base timing does need to be set now and then
Now would be a good time
Need a timing light
Need to unplug the SPOUT Connector which will be near the TFI module(ICM) that you changed on the rad support
SPOUT is a plastic connector on 1 wire, you pull it out and that disconnects Computer(PCM) from the spark system, so you can set base spark timing without PCM interference
Based spark timing is 10-12deg BTDC

The timing light will also tell you if spark is the issue for the rough running, because you should adjust base timing on warm engine, so if the strobe is not steady then spark IS THE ISSUE

1994 3.0l spark system is autonomous, the TFI module with coil and distributor, does spark for start up and RPM advance no need for PCM input
The SPOUT wire is for "Vacuum Advance" AKA Load advance, the PCM has sensor inputs so it can calculate engine load and best air/fuel mix, air/fuel mix decides best spark advance
But without the SPOUT/PCM connected to TFI, the engine can start and run fine it will just hesitate on acceleration

Anyway, fuel system don't tend to be effected by heat but spark system are effected by heat
Yes, you can pull out the PCM and open it up, there are 3 capacitors that leak/fail after 20+ years and can be easily replaced, but they only effect fuel system, 1994 PCM didn't have much for spark, just load advance, which shouldn't stall an engine


1994 shouldn't have Downstream O2 sensor?????
Should just have two O2 sensors, one on each exhaust manifold pipe

 

First.....thanks for taking the time to provide such a detailed response.

I'm still a bit confused, and maybe it's because Ford made modifications during 1994, but it appears I have both a distributor and a camshaft position sensor (which doesn't make sense to me either). Take a look at the picture and see what you think of this item, and whether it could cause a problem. O'Reilly's carries a replacement for it, not sure how difficult it will be to change out.

What are your thoughts on this part replacement?

Thanks again for the insight!




?

 

That's the TFI remote mount connector with sensor attached

Its the Hall Effect sensor and could be called a "cam sensor" in this application, but never heard that reference before, just called the Hall Effect sensor, but good info thanks
Yes, you can try a new one
Also check if distributor shaft has a wobble, but that shouldn't be a cold/warm thing, but anything electric can be



Inside the distributor is a wheel with windows and vanes that is attached to the distributor shaft, seen here: https://www.therangerstation.com/tec...ryarmature.jpg

On the "Cam sensor" you can see the curved slot this wheel spins in, Hall Effect sensor has a Magnet on one side of the wheel and the sensor on the other side, like this: https://www.therangerstation.com/tec...ibutorvane.jpg

As the engine, cam and distributor turn this Hall Effect sensor pulses 12volt on/off as the windows/vanes pass by the sensor, this is called the Profile Ignition Pick-up (PIP) signal, TFI uses this for timing on when to pulse the Coil off to send a spark, PIP is also sent to PCM for RPM and injector timing

 

Okay,

I ordered a new sensor, but it's special order, not arriving for a few days. Hopefully, access and removal of the old one, and replacement with the new one won't be too difficult.

I'll keep you posted.

Thanks again,

Jerry G

 

The Cam Sensor arrived and it looks to be the correct component as shown in the picture I sent you previously.

I thought this would be an easy removal/installation, but after removing the distributor wheel I found another piece of hardware that prevents me from reaching the cam sensor. I'm not sure if I should use a wheel puller device to spring the metal plate loose or if it's welded on, but it is in the way of accessing the cam sensor.

Please take a look at the pictures I've attached and give me your opinion on how to get down to the sensor. That rusty plate is a nuisance.

Thanks!