The Problem: When I start my Ranger it dies right away, I do this about 10 times or so (worse when it is wet or has rained) then I can finally keep it running, by hitting the gas. Once I get it running it will cut out while driving as well. The idle is normal and if fires properly, I just took it in to the shop (non-dealer) and they said it fires normal and has normal fuel pressure, and the their computer returned no error codes. Their sugestion was replace the throttle position sensor. Do you all think this part could be the cause and where is the this sensor and is it hard to replace?

 

I had the exact same problem on my 98 4.0L. Start it up, and it immediately dies. Keep your foot on the gas (not hard, just nudge it up closer to 1000rpm), and you can keep it going, even drive it (keeping your foot on the gas at lights), but it'll die immediately if you take your foot off. Mine was very flaky with the problem, sometimes it would do it, then a few hours later it would be fine. No codes, no CEL.

One time, I tapped on the TPS and the IAC and the problem seemed to go away (at least I was able to drive home without riding the pedal). I didn't have a chance to determine which it was, as I didn't see the problem ever again. I ordered both the TPS and IAC to have them in case it happened, I could replace them and know for sure, so I also replaced them both just after that because I didn't see it again and I figured I may as well be sure and use the new parts.

The TPS is screwed to the throttle body by two screws and has an electrical connector on it also. Basically, it isn't so much of a switch as a variable resistor that turns with the throttle plate. Very easy to replace, just unplug the connector, unscrew the screws (don't strip one like I did), pop the old one off and the new one on, screw it down, plug it in. There's a pic of the TPS below.

The IAC (Intake Air Control Valve) is a silver metallic cylinder hanging off of the plastic upper intake on my 4.0L. It is also 2 screws and an electrical connector.

-Jim

 

Sounds like your IAC valve, instead of the TPS. You can try cleaning it first to see if it helps.

 

I have a VERY handy litlle gadget called a sensor tester. It generates it's on reference voltage & monitors the signal voltage coming back from a sensor.

To test a TPS takes about 30 seconds.

If your mehanic isnt able to do something as simple as testing a TPS, it's time to find a new mechanic. Did the mechanic test the TPS?

As mentioned, this is more likely an IAC problem.

 

Seems to me, If either of these parts are faulty, there should be trouble codes set, so I'd look to your favorite autoparts store for a no cost, second opinion, computer trouble code scan.

Then post ALL the codes found.

If none are found, then test before replacement.

 

I wish there had been codes for mine. Unfotunately, there were none there. I have my own scanner and none showed nor was there a CEL. Perhaps his truck will be different, but I doubt it.

I'm not a big fan of blind replacement either, but when it happened to mine there was very little diagnostic information available. A "live" scanner might have better luck in saying what was failing. Now that I have a friend at a dealer, I could do it, but unfortunately the symptoms are gone.

-Jim

 

It does not sound like a TP sensor, I would expect that to give you problems while driving, not at idle and not at startup when cold. Try disconnecting the electrical connection to the TP sensor to see if that makes a difference. Suspect the idle control valve but that shouldn't have an effect while driving (except at idle). No computer code makes me think it is something besides an engine sensor gone bad. Because it is worse when wet I would suspect ignition (or electrical).
Hope that helps.

 

Try cleaning the MAF sensor.

https://www.ford-trucks.com/forums/s...hreadid=126093

Something else to at least consider:

https://www.ford-trucks.com/forums/s...77&postcount=5

See: https://www.ford-trucks.com/forums/s...d.php?t=315257

 

Thanks for all the tips and solutions. I will try them and see what happens. Thanks again.

 

I have the same issue on a 1994 4.0, I don't have a a code reader yet and I live quite a ways from town. I do realize this thread is almost 11 years old I found it and figured I would recycle it rather than start a new thread for the same issue.
Anyhow like I said same symptoms so I check volts on TPS and it is about 5 volts, so my voltage is where it should be. I could not find what ohms I should be seeing from the sensor so I unplug it altogether and it runs about the same as when plugged in maybe slightly worse.
So I am thinking almost 100% it is the TPS.
Rick

 

I really like Rockledges idea here, and it wont cost much to try it. Reps to Rockledge.

Since I like doing things the easy way I have a 30 buck Actron CP9087 sensor tester. It will test the MAF or TPS in a couple of seconds.

When my 87 Ranger was pinging and stalling off the line I pulled the codes and got a code for the TPS. Connected the CP9087 and in 30 seconds I knew the TPS was shot because the output voltage was jumping all over the place. I'm surprised the ECM/computer didn't have a nervous breakdown.

 

Perform this TPS operational test with your multimeter & let us know how it goes. Explorer: Testing the TPS (throttle position sensor). ECM code 124 - Ford-Trucks.com

 

On the TPS resistance readings, throttle fully closed, about 3-4K ohms, throttle fully open 350 ohms & the readings should change smoothly, no jumping around, hang-ups, or open spots. Use a analog multimeter for this test, as its easier to watch the needle sweep & detect momentary opens, than trying to watch the constantly changing digitial display.