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Rough Running 1994 4.0 V6 Auto       #: 739
 Moderated by: Mike69, MaDMaXX
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 Posted: Sun Apr 1st, 2018 11:36 pm
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RangerNed
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Hey there folks. Got bored in the fall and decided to change my valve cover gaskets. Easy enough process, right? Since I needed to remove all of the \"stuff\" to get to the valve covers I figured I would change the thermostat and the water pump for giggles, just because it was there. I put everything back together and fired it up. I crossed two wires and shut it back down. I developed a miss after that and then ordered a new coil pack, wire, and plugs (all Motorcraft). Ran great, for a while. Was traveling with the wife to the movies one night when the truck seemed to turn off at 45 mph. No notice, no engine lights, no noise, nothing. Whipped off to the side of the road and as I slowed down the truck just fired right back up as if nothing had happened. It did it a second time that night and I got her home and parked it (it isn't my DD and winter was coming). I did drive it to work one more time after this happened. On the way home it bogged down, wouldn't idle, and could barely get it to move under power. If I shut it down, it would fire back up and run, not great, but I got it home and parked it for the winter. It is decent enough to drive around now, but it is definitely not driving well at all. 

Here are the KOEO codes that I got tonight: 159, 159, 114, 157

My KOER codes that I got tonight are: 412, 116, 159, 312, 116, 159

Here is where I can use a little help. I found a site called \"easyautodiagnostics\" and checked out the MAF, and the TPS and they seem to be working properly (according to following the directions on how to check them). I have 34# of fuel pressure at KOEO (i did not see anything leak down while it was hooked up) but I did not check at KOER. Also, I haven\'t double checked to make sure that I am firing on all cylinders (hopefully when I have a second person around). When it does fire up it runs very poorly; I have black crap shooting out my exhaust. I am able to put parts into my truck if needed so that isn\'t an issue, but still, if the part is good why replace it? If i am missing other diagnostic areas, I am open for the help. A little guidance to check other things out would be awesome. Thanks in advance for the help!



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1994 Ford Ranger Extended Cab XLT
2WD Automatic 4.0 V6 OHV
MODS: LED Dashlights, Wired for OHC (don't have the guts to cut the headliner), Lighted Visors, Auto-Dim/Mirror, Auto Headlights, other than that it's pretty much stock
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 Posted: Mon Apr 2nd, 2018 10:18 pm
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Undrstm8ed
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RangerNed wrote:
Hey there folks. Got bored in the fall and decided to change my valve cover gaskets. Easy enough process, right? Since I needed to remove all of the "stuff" to get to the valve covers I figured I would change the thermostat and the water pump for giggles, just because it was there. I put everything back together and fired it up. I crossed two wires and shut it back down. I developed a miss after that and then ordered a new coil pack, wire, and plugs (all Motorcraft). Ran great, for a while. Was traveling with the wife to the movies one night when the truck seemed to turn off at 45 mph. No notice, no engine lights, no noise, nothing. Whipped off to the side of the road and as I slowed down the truck just fired right back up as if nothing had happened. It did it a second time that night and I got her home and parked it (it isn't my DD and winter was coming). I did drive it to work one more time after this happened. On the way home it bogged down, wouldn't idle, and could barely get it to move under power. If I shut it down, it would fire back up and run, not great, but I got it home and parked it for the winter. It is decent enough to drive around now, but it is definitely not driving well at all. 

Here are the KOEO codes that I got tonight: 159, 159, 114, 157

My KOER codes that I got tonight are: 412, 116, 159, 312, 116, 159

Here is where I can use a little help. I found a site called "easyautodiagnostics" and checked out the MAF, and the TPS and they seem to be working properly (according to following the directions on how to check them). I have 34# of fuel pressure at KOEO (i did not see anything leak down while it was hooked up) but I did not check at KOER. Also, I haven't double checked to make sure that I am firing on all cylinders (hopefully when I have a second person around). When it does fire up it runs very poorly; I have black crap shooting out my exhaust. I am able to put parts into my truck if needed so that isn't an issue, but still, if the part is good why replace it? If i am missing other diagnostic areas, I am open for the help. A little guidance to check other things out would be awesome. Thanks in advance for the help!

So just for reference I'm adding these in here for others to see:

KOEO
159 - MAF fault, above or below normal
114 - Air Charge Temp higher or lower voltage than expected
157 - MAF sensor low voltage

KEOR
412 - Cannot control RPM during KOER high RPM check
116 - Engine Coolant temp higher or lower than expected
312 - Thermacter Air system/fault during engine run self test

I'd start with your TAB and/or TAD solenoid(s). The thermactor bypass and diverter valves are actuated by small solenoids called TAB (thermactor-air-bypass) and TAD (thermactor-air-diverter) valves. The computer tells the solenoids to open/close, and the solenoids in turn direct vacuum to the the actual diverter and bypass valves.

Those or one of those acting up would cause a vacuum issue throwing of MAF, Air charge temp following that and give you a rich indication. Thats the black smoke coming out, unspent fuel [White is coolant, blue is oil, black is fuel].. you're seeing a "rich" condition because the truck thinks its best to run rich as a self preservation 'limp mode'. and that would understandably explain the rough idle.

 The best way to troubleshoot this stuff is to use one of those hand-held vacuum pumps -- I think it is called a "Mitey-vac". put a vac gauge on it and then attach it to the various components under the hood and pump them up one at a time. If the vacuum holds, moved on. It's time-consuming, but I can't think of any other way to pinpoint the problem..

Also, I think the FPR on the V6 is supposed to be  at 40-42lbs (?) can't recall at the moment but if you pull the vacuum line off it should increase pressure and engine idle too. if it doesn't then it may be bad equally.



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 Posted: Tue Apr 3rd, 2018 01:14 am
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CBB9M
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After you have carefully and faithfully performed a visual and corrected anything under the hood, emission system, etc that needs to be fixed, there is one and only one correct way to address the codes you have found. That would be to fix them in this sequence: KOEO, KOER and finally, CM. You start with the lowest # code in each family, one at a time, fix it, clear codes, drive, check for codes. Repeat the just noted correct sequence. I cannot emphasize enough how important it is to follow that exact sequence when troubleshooting and fixing problems on Ford EEC-IV engine management systems. Also, it really helps to have the FSM since within it are diagnostic flow charts for the DTC's that essentially lead the way for a systematic, organized and methodical diagnostic process for each of them. Beats the snot out of guessing, hoping, hyphotisizing, posting and getting guesses, spray-n-prey parts swapping, and overall waisting time and money. FWIW, I bought the FSM for my old 94 around 96, great investment for many service reasons during the time I owned it. Anyhow, this all this will get you pointed in the right direction.

Last edited on Tue Apr 3rd, 2018 01:17 am by CBB9M



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 Posted: Fri Apr 6th, 2018 02:21 am
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RangerNed
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Hey guys! Thanks for responding. FWIW, I do not have an EGR or the other incidentals mentioned as part of my motor (that may have made things easier to diagnose)! I have a rather simple vacuum system on this truck and the lines seem pretty solid (no leaks). I had checked the MAF, TPS, IAC prior to posting and they had seemed to have checked fine according to the instructions that I had found on-line. I spoke with my son-in-law who had a Mustang at one point in time and on that car that he needed to change the ECT sensor.  I did a lot of reading on other ranger forums with similar symptoms to what I have posted and the ECT (engine coolant temp sensor) was mentioned several times as a possibility. So tonight (Thursday), I said the heck with it and replaced it (AZ Duralast part $22.00). The connector on the sensor was rusty and covered in dirt. I cleaned the female connection and tightened things back up. Pulled and cleaned the plugs (driver's side plugs were pretty fouled up). Turned the key and things fired right up. No stumbling, no rough idle, no crap blowing out of the exhaust. Drove around for a bit and was coming home when it threw a CEL.  

The codes KOEO: 159 157 177     KOER: 137

Do you suppose these are the aftermath of what went before (way too rich condition)? I do not know if any of the O2 sensors have ever been changed on this vehicle. Thanks for any guidance.



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1994 Ford Ranger Extended Cab XLT
2WD Automatic 4.0 V6 OHV
MODS: LED Dashlights, Wired for OHC (don't have the guts to cut the headliner), Lighted Visors, Auto-Dim/Mirror, Auto Headlights, other than that it's pretty much stock
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 Posted: Mon Sep 3rd, 2018 08:07 pm
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RangerNed
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Hey there folks! It has been a long summer (too short if you live in Michigan!) The reason for the original post was twofold. The first being that the truck motor would cut off and turn back on while driving with no notice. The second reason was for the "rough running" symptoms that I was experiencing. I did a lot reading/researching in most all of the Ranger Forums and there are many, many posts just like mine. The problem was that I did not come across any with any solutions. Like I stated in one of my earlier posts, all of my major sensors checked out OK. I researched our ignition firing system (EDIS6) and checked the components. This is what I found at my Crank Sensor:

I thought that this may have been the cause of my problems, especially with the motor intermittently cutting out. So, I taped the wires carefully and plugged it back in (I will be changing the plug this fall sometime). The truck drove great for a couple of weeks. Great, its fixed!! Then I drove the truck to my sister's in KZoo and (2) miles from her house and the truck cuts out!! I got it to limp there and then later in the evening I had to drive it the 2 1/2 hours back to "Metro Shores". The truck wouldn't drive over 68 mph and I had to leave the CC on to get home. If I had to come off the CC the truck would die. That was a fun drive home!! Not. Anyways, more reading/researching and I found this video: 



So I figured what the heck do I have to lose? I pulled my PCM and sure enough, just like the video, one of my capacitors had leaked out. I replaced the (3) capacitors per the video for a whopping $5.00 (highway robbery actually, since they are less than a buck a piece on line). Re-installed the PCM and the truck has been running great ever since!! So, I hope this helps someone out with an actual answer to their "rough running" Ranger problem.



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1994 Ford Ranger Extended Cab XLT
2WD Automatic 4.0 V6 OHV
MODS: LED Dashlights, Wired for OHC (don't have the guts to cut the headliner), Lighted Visors, Auto-Dim/Mirror, Auto Headlights, other than that it's pretty much stock
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 Posted: Mon Sep 3rd, 2018 08:37 pm
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JAMMAN

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That is a substantial discovery and a great ending to the story! Thanks for sharing it!

I would still replace that crank sensor plug though.

Was there anything in the articles you read that explained why the caps leaked? There is usually only a couple reasons why a cap lets go... over voltage, bad run of capacitors to begin with, poor circuit design making the capacitor work too hard.Basically they are lazy, if you even run one at rated voltage it will puff up after a while. Some of the early ABIT server motherboards had a problem with this. Trust me LOL.



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00 XLT 2WD RCSB 5.0 swap Gherkin
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00 XLT 4WD RCSB 3.GO! Jalapeño
00 XLT 4WD RCSB Steppie 3.blown. Mistake
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00 XLT 2WD RC Steppie 2.5 Dee Dee

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 Posted: Mon Sep 3rd, 2018 10:44 pm
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RangerNed
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Jamman, no. I do not know why the capacitor failed and I did not read anything as to why it would. I assumed "old age" as my truck is 24 years old. My electronic knowledge is no way near yours. I basically watched the video and did it, which means pretty much anyone can. If it did not work, I would have had to buy a "new" PCM anyways. Any how, from the reading/research, it would appear that most PCM repair would have been replacing the capacitors as a start.



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1994 Ford Ranger Extended Cab XLT
2WD Automatic 4.0 V6 OHV
MODS: LED Dashlights, Wired for OHC (don't have the guts to cut the headliner), Lighted Visors, Auto-Dim/Mirror, Auto Headlights, other than that it's pretty much stock
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 Posted: Tue Sep 4th, 2018 12:22 am
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I love endings like this. You did the research, found the issue, and fixed it without just throwing parts at it. And you're more educated for it. Nicely done!

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 Posted: Tue Sep 4th, 2018 12:36 am
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JAMMAN

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And since you shared, we all learned something. Kudos :)

50 rep points to ya



____________________
00 XLT 2WD RCSB 5.0 swap Gherkin
00 XLT 4WD XCSB 4.0 G2
00 XLT 4WD RCSB 3.GO! Jalapeño
00 XLT 4WD RCSB Steppie 3.blown. Mistake
99 XL 4WD RCSB 3.0 PJ (Plain Jane)
00 XLT 2WD RC Steppie 2.5 Dee Dee

ALL Amazon Green Metallic
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 Posted: Sun Sep 9th, 2018 12:13 pm
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Mike69

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Good job & thanks for posting your solution to what fixed your problem.



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08 Escape 4x4(spare)
00 Ranger Extd Cab 4x4 4.0 OHV, Auto(My DD)
99 Explorer Sport 4x4 4.0 SOHC, Auto( Wife's DD)
69 Mustang Coupe 5.0, 5 spd(Project & my future toy)
14 Kawasaki Vulcan (Wife's Toy)
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