Now I need help...

[a31ford]

.
Ok people, I need to ask a question (OMG, NO not a31...

I've got an issue after the truck gets up to temp. (Closed loop mode).

Truck will "stumble" and "fart" while doing highway speed, (1800-2500 in 5th) but ONLY after it's warm, (tach bounces around as well) BUT, until then it acts like it has a supercharger on it, power like crazy, and no tach bounce.

One Other thing, the ALT lamp (beside the engine lamp) "Flickers" some what, BUT, only while letting off on the throttle, if you even "Match" the speed you are doing (or accelerate) the ALT lamp quits flickering.

It's a random flicker, and only when it's stumbling.

the flicker is NOT in time with the stumble, BUT only is present when stumbling with the throttle 'backed off".

TFI is new, Codes in both KOEO off and running KOER are "11"

The only thing I can think of for Diag, is remove the PIP jumper and see if it still does it when warm, this would rule out the ECM and TFI.

Greg

 

[kimcrwbr1]

Have you cleaned all your connectors and sanded all the grounds metal to metal maybe a shorted wire to a O2 sensor. Look for any burnt cracked or broken wires especially around the exhaust solder splice and shrink wrap all repairs if possible. Clean all the electrical connectors you can find with electrical cleaner use dielectric grease to put them together and push the pins on both sides with a small screwdriver fully in. sand all the grounds you can find. I believe you mean remove the spout jumper do that and check the timing is correct and steady. Intermittent faults are normally wireing/ground related. Go throught the wiring and then pull the codes if it dont cure the problem.

 

[kimcrwbr1]

The computer has several grounds find them all and make sure they are good. I like to do things in sections and see if it fixes the problem. If you do a bunch of stuff at the same time you dont know where the problem actually was unless you find a bad wire then you fix that and immediately check it out.

 

[a31ford]

totally agree with you. one thing at a time.

Some time today, I'll do the spout thing (ya, that was what I was talking about), I'll check timing (was good a month ago, BUT you never know). and then leave the jumper off, and go for a drive (I know this will set a code) but I'm thinking that if it's a bad coil or SP wire, It will still do the stumble thing when warm.

It could be that the alt light is just a coincidence, and it simply needs brushes..........


Greg

 

[alwaysFlOoReD]

You're more knowledgeable about electrical than I am so I don't see me helping much. However, I have a question.... Is it possible for the alternator diodes [or whatever that controls current] to be loose in such a way that they only screw up in a coast situation?
The stumble /fart....I've had the same problem and never found the answer, but next time, boy oh boy, watch out! I've bought some books and have been watching the trs forums like a hawk.....oh who am I kidding [jk]
Could the open loop mask a mechanical issue? such as valve guide wear, sticking valve - though I don't know enough to know if that would cause the symptom.

Richard

 

[RonD]

For the alternator you may have a bad "jumper" connection or failing regulator.
This diagram:
http://www.therangerstation.com/tech_library/EDiagrams/files/Diagram_charging_1991_2.JPG

It shows the charge light indicator wiring, it operates from the "jumper" wire and regulator circuit, the "jumper" can have a bad or partial connection, I would give it a close look.

With all lights and accessories off the voltage at the battery with engine idling should be about 13.8volts.
If you then turn on all lights, fans, radio, and anything else you can think of, the voltage should drop then come back up to above 13.6volts, if you raise RPM it should go up to 14+volts
If voltage is lower in general then at least 1 of the 3 fields(stator) in the alternator has failed, this reduces the overall amps the alternator can provide under load.

The charge indicator circuit also powers some devices via a 10amp fuse, not sure what those are, but since the stumbling does not occur at the same time it is probably not related.

Since there are no trouble codes, 11 = OK, maybe fuel pump screen or filter is partially blocked, fuel supply is being limited in higher RPM after 5 to 10 minutes, seems like a long shot though, a partially blocked fuel tank pressure return could be causing negative pressure in the fuel tank, limiting the ability to suck gas from the tank after awhile, you could remove gas cap and run for a bit and see if it helps.


The 2 wire Coolant temp sensor decides when system should run in closed loop, if it is giving wrong reading system may stay in open loop, but that usually doesn't effect higher RPM, but if sensor has failed near closed loop OHM point it could be jumping back and forth between closed and open with normal engine temp getting cooler and warmer under load and then no load.
Or it could just be a loose wire, lol.

 

[a31ford]

Small update, (had to do a service call yesterday afternoon), So.... I pulled the SPOUT connector and engine ran well, BUT, I didn't get a chance to get warmed up. today, I have to go to town, SO, I'll do the timing check and run without SPOUT (I'll code all three after the run)

until then.

Greg

 

[a31ford]

`
FOUND IT !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

(Well Kinda...) Caught it in the act... ECM connector, at the low end (as mounted) the bottom end of the connector, (in the 1,21,41 end) haven't exactly, BUT I'm able to kill the engine by just moving wires.

will follow up shortly.

Greg

 

[a31ford]

`
Latest update (went to town today), After the killing it with touching the ECM connector wires, I got it going with NO stumble, NO farting, BUT, the ALT light is still flickering (coming home). SO, What it comes down to is that the harness has a bad wire(s) IN the harness about 6-8" FROM the connector (IMO it's from other people dicking around with the ECM and breaking the copper strands in the harness wires, so far, about 4 are "spastic").

Another thing is that the ALT light gets it's power from pin #4 of the ECM, for now, I'm going to assume that this is also a harness issue, as it WAS OK, until the trip home.

Wreckers later this week for a new ECM and the harness part about the first 3 feet including the connector......

Can you say "linesmen's wrap, and miles of heat-shrink, and solder" ??

Greg

 

[RonD]

Nice work in tracking that down

 

[Andy D]

So far, I have just had to re- terminal some of the wires to the starter and wired a new radio to the existing speakers. But that is it.

Old car wiring is a PITA. The insulation gets brittle and the colors fade or get dirty. Wires fray at the ends. As stuff rots out, wires get wet and turn into green mush.

I'm a low voltage tech, I used to work in COs and comm rooms. 25 pairs or 28 pair cable. I'm down with color codes and DC voltage and meters and stuff. I just pretend I'm tracing a bad line. Patience (stubbornness) helps.

 

[a31ford]

Small update (we just got over a foot of snow in 10 hours.)

Pin 26 in the ECM, it's the common voltage reference for TPS, and MAP (throttle & air pressure).

If I touch the wire about 4" from the connector (while holding the wire AT the conector steady, moving the 4" away part, I can kill the engine....

LOTS of other things found, #3 had a plug that showed "open" (all others where roughly 7K ohms resistance (which is common for resistor plugs)

#3 also had a funny glaze on the porcelain in the tip, replaced it. with a known good plug. (would attribute the glaze to the open).


took the brushes (and IR) out of the Alternator (blinking BATT light on dash). found film of grease on brushes, cleaned, and slip rings cleaned, NOW, the light stays on, UNLESS you rev the engine, BUT, charges no problem, (thinking the "stator line") still working on that one.

The IDM line (can't remember the ECM pin for it) in the Haynes manual it says that it ges to the instrument cluster AFTER the 22K resistor. WTF ? is this the line for the SEL lamp ?

Gona have to rip the dash apart.

So far..... bad cap on the little board that runs the fuel level sensor (this would explain some OTHER issues I was having..)

FUNNY, the cluster on top of it has a sticker, "For 4.0L ONLY" now I KNOW this is a parts truck....
Still working on it.

As I get into it.... The TPS is now throwing a code (over voltage) 53, and setting the SEL almost instantly (about 3 seconds after starting, HOWEVER, voltage is 5 on the nose, BUT, here is the funny thing it was doing a 23 (Clutch Sw failure) changes the multi function (6 wire) switch on the pedal shaft, after that BANG, 53 over and over every start.

Slowly getting there....... Mar 5/13 6:45 pm

THIS TRUCK IS POSSESSED, PERIOD !!!!!!!!!!!!!!!



Greg

 

[a31ford]

Final Thoughts for today (Not done yet).

Many prior owners of this truck have "Had there way" with the wiring I've traced and fixed over 61 wiring problems since I purchased this truck.

Everything from "extra grounds into the engine harness" OMG ! to some weird 9 pin connector in the steering harness (I know the connector is NOT OEM).

ever so slowly, the truck has gotten better and better, starts easyer, better on gas, more power, and last but not least, MORE reliable.

The T-case, front and rear ends are in awesome shape, body is not bad (rear fenders above wheels).

for the 500 bucks I paid for it, (and drove it home), mind you I did have an engine head anti in oil problem.

All told, 2000 into it, (and counting) was/is it worth it , DAM RIGHT it is.

Greg

 

[Andy D]

Yah , I pretty much did the same thing with the Rat. You dont get much vehicle for 600$. But 1200$ gets you a lot of parts. I am quite satisfied with the Rat. It was a rescue from the crusher. Had I known more about Rangers, I wouldnt have bought it. Way too much money and time was spent making it the total heap it is today.

 

[a31ford]

OK, so I've had a Scope on every line out of the ECM, and Found the issue,

It appears that at some point someone added an extra ground to the floating negative that runs the HEGO, MAP, TPS, ACT, & ECT (pin 46 of the ECM)

Because this is NOT to be grounded except at the ECM, I measured a 1.2 volt "offset voltage" that was fooling ALL the above sensors..

NOW.....

FLIPPIN FAST, (for a 2.9) climbs even steep hills in 5th (at 70) with only a small decrease in RPM).

AND...... best of all 140 miles (mixed 100 hwy, 40 city) on are you ready... NOT even 3 gallons of fuel, WOOOOOOOO HOOOOOOOO !!!!!!!!!!!!!!!!!!!

Done, thread finished.

Greg