Alright to get you guys up to speed I just bought a 94 Ranger 5 spd 4wd with a 3.0 v6. It has 89k miles on it. I got it cheap cause the guy couldn't get it running right so I bought it thinkin it would be a simple fix, but i havn't figured out what that "simple fix" is yet.

1.The truck had a horrible mis-fire when I bought it.
2. No power
3. When first started it would idle normal then rev up to about 2 grand and misfire horribley for about 5-10 seconds (sounded like it had a monster cam)
4. If you shut it off or stalled it, it wouldn't start up again till it had sat for hours (the cooler the engine is the quicker it starts).
5. Check engine light would come on when truck was at idle but go out when moving/reving.

The previous owner said the truck had a new fuel pump (FP), throttle positioning sensor (TPS) and mass air flow sensor (MAF).

As soon as I got the truck home I installed new air filter, plugs, wires. 2 of the plugs were completely fouled out and soaked in fuel. Changing these things made no real differance.

I sent the truck to the local ford garage to have them pull codes, check for vacuum leaks and put in their two sense on the issue. They told me they found no vaccum leaks but they said the cap, rotor, intake air tempeture sensor and throttle positioning sensor were bad. And they pulled the codes...
114 Out of range voltage air change temperature sensor (ACT)
116 Out of range Engine coolant temperature sensor (ECT)
118 High voltage Engine coolant temperature sensor (ECT)
121 Outside range throttle position sensor (TPS)

So after getting it back to my garage I replaced the ECT, ACT, TPS, cap, and rotor.

The cap and rotor replacement helped with the misfire a lot. The ECT, ACT and TPS replacement really didn't do much, if anything.

I went ahead and replaced both O2 sensors. This seemed to help it get some more power but still you had to slip the clutch like crazy just to get the thing to move.

After all of this the truck now has a slight miss-fire, still is running pig rich, has a little more power then it had before but not much, check engine light still comes on, idle still jumps around when first started, and still if you stall it it still won't start again till it has sat a while (like it won't even try and start, just turn over).

I found a new PCM on ebay that I'm thinking about buying. I'm running out of ideas for this truck quick. Anyone have any other ideas for me to try? I'm gonna change the fuel filter here this after noon we'll see how that goes. Thanks for the help guys!!!

Sorry this is long but I'm trying to give as much info as possible. Thanks again!!!

 

Little update here.
I don't know if it makes any differance but while I was writing this up I left the truck sit outside idleing to let the computer re-tune a little and when I went out it was idleing at like 2200 rpms and didn't idle down till I tryed to move it. Still runs like crap. haha but just figured I'd throw that out there.

 

Sounds like a bad vacuum leak but with other underlying issues. Can you hear any sucking noises under the hood?

 

Its already been tested for vacuum leaks and none were found.

Also I just replaced the fuel filter and still no differance, i poured water through the old filter and it flowed fine through it.

 

Alrighty update. So I got the truck running good today. Go figure the dude that had the truck before me put the spark plug wires on backwards for cylinders 1 and 2. I never cought it cause when i did the wires and cap and rotor and what not I just put it all back together the same way they already were. STUPID. Anyway still when u shut the truck off after its warm it doesn't seem to want to start again till it has sat a while.

It still has spark and I can hear the fuel pump prime but i'm guessing the injectors are not firing because it won't even try to start. Does anyone have any ideas as to what would cut power to the fuel injectors? I know their is a fuel shut off switch on these trucks somewhere but i don't know where and if the fuel cut off switch was the problem would the fuel pump still prime?

Any help would be appriciated!! Thanks!

 

I keep answering my own questions. But I found the fuel shut off switch and tested it. Its good. I AM getting fuel. I AM getting spark at the coil. But not at the plugs. Every once in a while i will get a random spark at the plug but not offten. There is a plug in the back of the distributor, can anyone tell me what that is for? i'm guessing there is some type of sensor in there and I think that might be my issue... thoughts?

 

You guys have been so much help! (sarcasm noted) :/ But I decided to go with the ignition controle module and that got rid of a very slight miss that i still had but the truck still won't start after it has run a little. The pick up assembly is my next guess but I just don't see how that would be heat sensitive.

 

The pickup in the distributor bowl can become heat sensitive. When it goes open, you get no spark. Have you checked the fuel pump pressure? The regulator could be setting the pressure too high, and causing too rich a mix. The injectors could be dripping after you shut it down hot, and loading up the intake with extra fuel making it hard to start after you have run it, and then let it sit for a short period of time. Try cracking the throttle open a smidge when you try to start it hot.
The TFI module, mounted on the distributor, has several contacts that mush into connectors on the bottom side of the distributor. The contacts, female style, are molded into a plastic piece that is in turn fastened to the inside of the bowl. If the plastic deteriorates, which it does, it can allow the female connectors to 'move away' from the male connectors on the top of the TFI. You would then get intermittent contact from the TFI to the pickup... Does that sound familiar?
There is a plug i the harness, mine is near the distributor, yours may be over near the battery under the plastic cover, that is disconnected to set the base or static timing. With the plug out, the ECM won't mess with the timing, leaving it for you to set the distributor to 10deg BTDC. After you set the base, put the plug back in, and the ECM will take over from there handling the timing chore. If you don't do it right, the engine will be gutless, well, mine was.
tom

 

On the too rich problem, pull the fuel pressure regulators vacuum line & see if it's wet inside with fuel, if so, the regulators diaphragm is leaking fuel into the vacuum line/intake manafold & causing an uncontrolled over rich air/fuel mixture, so replace the fuel pressure regulator.

Have you rescanned the computer for any remaining trouble codes???? If so, post all code Numbers, as they can offer up good trouble shooting clues.

Most autoparts stores will scan the computer at no cost, if the CEL is lit, or your having problems

After scanning for any remaining codes & all of the new parts replacement/repairs you've done, have you pulled the B- battery cable to clear the codes & wipe the computers KAM, so it can begin to build new fuel trim tables, using the PID inputs from the new parts????

I like tomw's ideas on checking fuel pressure & while your at it, do a pressure leak down test too, as it can point to fuel pump, pressure regulator, or injector problems. I like his TFI ideas too.

Keep us posted on your finds.

 

Alrighty thank you pawpaw and tomw for the help! The pick up ended up being bad. I got a good deal on a whole new distributor and put that in and timed the truck. She seems to be running great! No stalling and it starts every time.

The only issue I am still having is the idle is still really high. When you first start the truck and it is cold it will idle around 2000 rpms which seems fairly normal when cold, but after it runs about 10-15 seconds the idle will drop suddenly to about 1000 rpms then the truck lopes like it has a heavy race cam for about another 5-10 seconds, then it revs up to about 3200 rpms and will hold there for about 3 minutes, then it will idle down to about 1500 rpms after its warm.

Both the idle control valve (that sits ontop of the throttle body) and the throttle positioning sensor have been replaced with brand new ones.

If you unplug the idle control valve when the engine is warm it will idle normal (around 800 rpms). I would just run the truck with out it plugged in but the truck has trouble starting up with out it plugged in.

Is there anything else that controls the idle on the truck other then the idle control valve and the throttle positioning sensor?

The check engine light is on, but none of the shops around here have the tool to read it accept the ford garage and they want to charge me an hour labor to pull the codes ($68) screw that. If it comes to that I will do it. I really need to get this truck running good soon.

 

Without pulling codes and looking at DCL display data (you know, DIAGNOSING the problem) you are likely to keep throwing money at it. You already replaced some parts that were probably good. Just because you have a code for a sensor does not necessarily mean the part is bad, and in fact it usually isn't. For example, the ECT code you got could have been from the Ford tech running the self test without the engine warmed up. It could also be a problem with the PCM, or any of the connectors or wires in that circuit. Unless you actually check these, you are wasting time and money.

One of the codes you got before was for the TP sensor. This rarely means the sensor is bad. It usually sets because someone has been messing with the throttle stop screw on the throttle body. Contrary to what some think, this is not used to set idle speed like on a carburetor. It is used to set the closed throttle position of the throttle plate, and must be set to very tight tolerances using a multimeter or a scan tool as directed by the shop manual. If it is not set correctly, you will have hard starting, erratic idle speeds, and the MIL on. Sound familiar? What value did you set the TP signal to when you installed it? It is not plug-and-play.

My advice is to have someone competent recheck the system after the changes you made. By competent I mean more than just pulling codes. Codes only tell you what the computer sees is out of range. They DO NOT tell you what to replace. Around here, $68 an hour is less than the corner gas stations charge. Most dealerships are in the $90-100 range. It sounds like you are getting a bargain.

 

Alrighty well I drove the truck to a garage today and got the codes pulled. FireMe I think you are right about the throttle positioning sensor not being set right, because the shop said that was the only code that came up this time.

I looked around in the forum and I'm sure its here I just can't seem to find it, but how do you set the throttle postioning sensor? I'm used to the ones that you can just loosen the bolts and move it till a certain reading is made then your in good shape but this one is new to me.

Thanks guys!!

 

UPDATE:

Disregard that last message. I ended up finding out how to set and test the throttle positioning sensor. The wire that is supost to be around .95 volts is at 4.50v at idle and 6.30v at WOT. I tryed my old tps and it gave the same reading. So is that telling me that my main computer is scrap metal?

Here is what the wires that go to the TPS are reading:
Top (ecu current) 4.80V
Middle (tps sending wire) 4.50V
Bottom (ground to ecu) "if i test the voltage from the battery to the ground" 8.80v and the actual battery voltage is 14.30v

So there is some resistance on the ground for the TPS, is there any reason I couldn't cut that wire and make a direct ground to the battery?

 

Post All of the trouble code Numbers found.

The computer provided TPS V-Ref voltage should be 5 volts to ground at KOEO.

At KOEO, the reading from the center TP lead, to the Sig Rtn lead with the throttle closed, should be between .5-1.0 volt. At WOT it should read between 4-5 volts.

With the throttle fully closed & the TPS electrical connector disconnected, you should read 3K-4K ohms, between the TP & V-Ref terminal. At WOT it should read about 350 ohms between those terminals.
The resistance value from Closed to WOT should change constantly, but smoothly, no flat spots, opens, or erratic readings.

 

Make the checks like pawpaw said and show us the specific code they pulled.

To make sure we are on the same page, the three wires at the TP sensor are:

Signal Return: A dedicated ground for the engine sensors.
TP Signal: The variable value that correlates to throttle plate angle.
Vref: A 5.00v supply circuit that feeds many of the engines sensors, used only by the PCM.

There is no way your TP signal should be 6.3v. The sensor is only fed 5v so all values must be less than this unless there is a short to power on the vref circuit, which would cause many, many other issues. Is it possible you were measuring incorrectly?

Checking the signal return circuit to the negative battery post should give a value very close to 0.0v. If not, you have either a harness problem or a problem within the PCM.

DO NOT ground the signal return circuit. This is a dedicated ground used only by the computer components. It is buffered to reduce noise on the system. Connecting it to chassis ground will cause other problems.