Hello guys, new person here but have successfully used your forum working on my truck for the past 2 years sop first off thank you for your write-ups! Many posts on the 2.9 curse but still need a little information..

So I have a 1986 Ranger for about 4 years or so, it is a Long bed, 2 wheel driver 2.9l v6 automatic.. Only has 79,000 original miles from an old man. I absolutely love this truck.. at about 100k miles I got the 2.9 curse... sounds like it was running on 1 cylinder.. replaced spark plugs as they were very very fouled ran rich smelled gas... added best spark plug wire set (only 40 ohms of resistance Standard Ignition Blue Streak) new cap...CURED... 3 months go by does it again.. replaced the rotor under the cap as I apparently forgot all Standard brand Blue Streak added a new fuel pressure regulator CURED added new Standard bran coil to match.. 3 days later, same thing.. smell gas, fouled plugs, won;t really run when it does sounds like its BARELLLY running like 2 cylinders.. i bought a new o2 sensor have not put that in...

I saw a youtube video seen here


So I bought standard brand fuseable link wire in the correct gauge... cut out that part of the wiring harness as seen in the video.. first thing I noticed the wire in the 1986 Ford Ranger harness in cheap garbage ALUMINUM!! Spliced it on perfectly... CURED truck is fixed AGAIN..... 2 days later not cured same 2.9 curse runs rich, wont start if it does start sounds like running on 2 cylinders ..

My friend told me there is a company called "Painless wiring" and they can make a new custom harness, that will likely not be crap aluminum.. SOO here is my question.. Would a new quality wiring harness fix the 2.9 curse or is it merely mechanical in nature? Or both wiring and mechanical? I see people on these forums and The Ranger Station with my same trick and some of these people have way more miles on their ride...

I have found a local mechanic that has done engine conversions for Ford Rangers and am ready to pay him to put a 2.3l 4 banger of a 4.0 v6 in it and junk my poor 2.9. Before I do that was just wondering if there is anything else I should try? I'm trying to figure out if its even worth it because I have seen so many 2.9 threads were poor people LITERALLY replace dang near every single thing they can throw on to it...

OH BTW when I spliced the new fuseable link wire in I also replaced the MAP sensor and it worked and was "cured" again for only 2 days.. forgot about that part.So there you have it... junk my 2.9 with 100k miles well taken care of, or junk entire engine or look more into a custom wiring harness? Not getting rid of this truck, body is in awesome shape... found a $55 same era black aluminum canopy for camping, new brakes I did myself etc.. love my truck.

Sincerely,
Knight Owl

 

Welcome to the forum

Pull out the computer and check its 2 or 3 cylinder capacitors, they tend to fail after 20+ years, easy fix
Also just give a good look at the circuit board, clean it up, and check the connector pins, need to be corrosion free

You replace FPR(fuel pressure regulator), thats good
What about the ECT(engine coolant temp) sensor?

Replace the 1 O2 sensor if you haven't yet, they only last 12 years, these are the ONLY sensor that has a time limit

 

Thanks for your reply RonD!
I didn't think my 1986 Ranger had a computer? Are you referring to the MAP sensor/computer? thats mounted right on top, high in the back just under the hood and literally just plugs right in? And how do I know if its a 2 or 3 cylinder capacitor? I'll look at this circuit board too... I'm not naturally mechanically inclined but worked at a tractor shop for 8 years so I've been able to do everything so far, feels extremely rewarding too.

Definitely have not done a ETC temp widget, I'll buy one asap. Have not bothered with the o2 sensor yet but I will now, thank you. Thanks in advance about this "computer" and the curious 2 or 3 capacitor, definitely am jot familiar with this part and trick. Thanks again, in the mean time I'm going to try to figure out where this computer is if its not the MAP sensor.

Sincerely,
KnightOwl

 

In 1986 computer is in the cab behind passenger side kick panel

Pretty much any engine with fuel injection must have a computer

 

Thank you again, I'll scope all this out on the weekend. I already ordered the ETC Temp sensor, I have the o2 sensor and am looking to buy the special socket tool for it, I'll likely take photos of the computer area, I had NO CLUE about the computer behind the passenger side kick panel!! Thank you so much! At that point I'll have some pics and harass you about capacitors or whatever I find. Thanks again

KnightOwl

 

So is there a good and bad way to pull pout this computer to see if there is 2 or 3 cylinder capacitors? I admit I'm overly careful with electrical stuff because i seem to not get along with computers.. Thanks again, I'm anxious to figure out this computer see if she needs replaced. Thanks so much bro.. appreciate it, worried if i take it wrong I'll yank some wires or something.

the sticker on this computer box says,

EEC-IV, EFI-SD6, BK (BACKWARDS "N"ROM

E6TF-12A650-E2A 6EC2336A03 4670-420 6F09

Sincerely,
Knight Owl

 

I would unhook one battery cable before pulling out computer

You should be able to slide computer up now.
Unclip the black plastic cover from wiring and you can then access the bolt holding the connector to computer, unscrew it, bolt doesn't come out all the way but you will feel when its unscrewed

Pull off the connector
Pull out computer all the way and open it up

E6TF-12A650-E2A

E6 = 1986
T is truck
F is electronic part

12A650 is Fords part number for ANY engine computer in ANY model, still used in 2021

E2A is the firmware/software on this computer, its important but only for 1986 and Ford NEVER released a cross reference for these numbers
But it is specific to engine size and transmission type

 

WOW, you know your stuff... Thank you! I would have totally forgotten about unhooking the battery cable. ANY computer ANY model lol funny Ford.. Great information thank you, I'll give this a whirl and see her condition and if it has 2 or 3 widgets. Thanks a lot!

KnightOwl

 

So I take it I have a unit with 2 cylinder capacitors? Looks like its corroded just like you said, what do you think? Appreciate your help, we've had so much rain and today its nice out so I'm all over this thing today. I also see 2 things that could be the WTC temp sensor both under the intake, one is a 1 wire the other a 2 wire but have no IDed those guys yet but one thing at a time... Thanks so much. You were totally right about this computer!! Guessing I should replace it... i think ill try orileys carid or autozone... tell me what you think and thanks a million..

KnightOwl

 

Use Q-tip with isopropyl alcohol or electronic contact cleaner(MAF Cleaner) to clean up the corrosion as much as you can
Also open up computer and check its internal contacts and the board in general, same cleaning as needed

Electronic cleaners are just very low water fluids so they don't leave residue behind that causes more corrosion

Do NOT use di-electric grease on metal pins or slots, the point of using di-electyric grease is that is does NOT conduct electricity, so can't cause a short inside a connector
You can use it on the plastic areas so when the connectors are pushed back to together it seals it against moisture getting back in

 

Hey Ron! Had another break in the weather snow/rain.. we opened up the old computer after cleaning the pins and everything inside had green corrosion dots so we chucked it got a core charge and installed the new one.. battery still unhooked.. all I need to do now is the new non fouled spark plugs and the Electronic Temperature Control Sensor ..idiots at the parts store kept ordering automatic window switches lol. I bought the motorcraft version as it was the only one with a 2 year warranty. I've still been getting conflicting info on where to mount it, I see 2 sensors in close proximity but I'll take good photos when the weather breaks again this week.. The new one didn't come with any wires so I might end up having to replace the wire connectors but we will see.. Thanks again for all your help..

Sincerely,
KnightOwl

 

The temp sensor for computer has 2 wires

The temp sender for the dash gauge has 1 wire

 

Dang your good, you keep it so straight forward and easy...I went ahead and replaced bout the sender and the sensor... topped off the fluids, even with my weak battery from sitting so long it started right up!!! Smoke isn't black.. doesn't seem to be running rich or fowling plugs... I can't believe it! You sir certainly know your Ford Ranger 2,9... I'll do more testing tomorrow on a cold start and see what happens, but my, Super grateful! No one else has match your knowledge.. Just curious what part of the country are you in? Thank you, can't wait to test it more.. seriously impressive!

 

Good work


Live near Vancouver, BC, Canada

 

Wow, always wanted to see BC... Most beautiful territory I know of for what I like.. Thanks again! You just saved me re-engine-ing this whole vehicle! I changed the bulbs out of the dash too, now I'm going to fix the windshield wipers they don't turn off. with the money I save I will re do the entire interior.. going to test it some more for a few days to trust my work, after all its a 2.9 lol but it did great today! Ron your my dang hero :o)

Jamin

 

Quick question, been testing it this week and it actually works perfectly. My only concern is I noticed my engine gets hot really quick, to the top line HOT... It has never ever run this hot before? It to my knowledge has never had a thermostat changed.. my question is when I bought the ETC Sensor napa said they had the good quality one (with the highest warranty) but they were misinformed and only had a cheap looking 19 buck one that I didn't like but bought to finish the truck so I wouldn't have to wait 4 days to finish my truck. Can a CHEAP ETC Sensor although brand new cause my engine to run HOT? The radiator antifreeze coolant looks fugly so I will change that, and was going to buy a thermostat... should I just do that, and shut my pie hole? I don;t know how long themostats are suppose to last or how often they should be changed... anyway thoughts appreciated. Just thought it was strange she has never run hot but I've changed alot of parts so maybe I pissed off this thermostat in a round about way ie domino effect? Thanks so much, the best warranty thermostat part i see is a motorcraft one with a 2 year warranty

KnightOwl

Thanks for everything.. been fun driving hewr to work all this week!!

 

There are 2 temp units on most computer fuel injected engines
The ECT sensor, which is 5volt and only used by the computer to set choke mode and when O2 sensor can be used, these always have 2 wires

And the coolant temp sender, its 12volt and only used by dash temp gauge, only has 1 wire up to about 1995 or so, engines have had these since 1930s, lol

Not at all interchangeable, lol

Yes, if engine is running warmer than usually I would flush it and install a new thermostat, 190-195degF, not 180deg
Also pull of both radiator hose at the radiator and flush the radiator
Put hose in upper rad hole and put garden hose on a reasonable flow, and make sure rad can handle it, doesn't back up in the rad, that means its clogged
Radiator can/should handle pretty fast flow or water without backing up
Also flush heater core in both directions, you should reverse the heater hoses at the firewall on any vehicle every 2 years to help it last longer

Leave a heater hose off when refilling the system, it lets the air out of engine side of thermostat, when water comes out out heater hose back on
Refill with water only after new thermostat and flush..............if local temp is above FREEZING, lol
Drive it a few days to see if its running cooler
If so then drain and refill with coolant
If not then there are other issue

 

WOW, Well I think we found the potential problem... we yanked the ****/drain plug widget...with the radiator cap OFF... LOL Literally NOTHING drained... my brother said to pull it out already and I handed him the drain plug and he laughed.. I poked down that hole with a small screwdriver... and it was covered in tanish greenish red colored gunk consistency of clay!! Bought some BLUE DEVIL radiator flush ran with water for 20 mins as directed and now we have a tiny but steady stream... ran out of light, cold now so will do it again tomorrow but it suggests if you want a more thorough flush to drive and or run it for 1-2 hours... so I will do that tomorrow and hopefully that does the trick... absolutely never seen anything like this have you? I have the new thermostat the 195 degree jobber as you suggested with new water-jacket something rather. They had many I opened the box and picked the one that has the beefiest spring.. what a crapshoot... most people told me get OEM part and nothing else, everything else sucked, but when I started reading reviews it said the exact opposite. The brand was some sort of FAILSAFE thermostat. See good bad reviews about all of them so who knows. I had no idea they could actually get clogged... very interesting to me.. Thanks again can;t wait to hopefully finish tomorrow. Also in the middle of the project my battery almost caught fire east fix for $168.00. lol Oh well better then having it go in the middle of the woods where I like to explore..

KnightOwl

Thanks so much, seriosuly though had no idea radiators could clog, I mean clay!? wth lol

 

well I'm running some more BLUE DEVIL in her right now, it stays at normal temperature only when idling... Once I driver down the street it raises to "H" very quickly, like before the end of the street. Kinda tricky, new radiators are only $166 so I'm trying to figure out at what point i stop putting money into my clay filled radiator. Thanks again I forgot to tell you, I have not yet installed the new thermostat.. My brother says my thermostat my have failed giving my a false reading of my engine overheating. but i dont know squat, all fairly easy work if i can get all t]he clay out

KnightOwl