Rough Idle, Missing, Pulling my hair out.

[DasBaldDog]

Okay,

After a year of spare time working on this truck, I'm at my wits end and ready to scrap it.

1994 Ranger 4.0 OHV (Has a leftover 93 engine in it, I think)

Tests done:
Tested MAF good
Tested TPS good
Tested Ignition Coil good
Tested Fuel Pressure good
Tested Compression fairly good/decent
Tested Vacuum good after LIM Gasket job

New stuff
Tried new ignition coil
Tried new maf
New ECT Sensor
2 new sets of plugs
2 new sets of wires
LIM Gasket
O2 sensors
Cat and Cat back exhaust (old one was rotted out)
New coolant
New fuel filter
New fuel pressure regulator
new speedometer cable
new clutch slave cylinder
2 new injectors and pulled all of them out and soaked in carb cleaner and blew them through with compressed air



She is missing, and is most noticeable at idle. I can't tell if its missing above 1000 rpms but the truck seems a bit down on power.

Tonight for ***** and giggles I unplugged the passenger side O2 sensor and I didn't even get a CEL.

BTW: All this time it's missing and down on power, low mileage, no codes of ANY kind.


While I was trying to reconnect the O2 sensor, I found a black 2 prong round plug/connector right on the main harness where the O2 sensors connect. Anyone know what it is?


And anyone have ANY idea what I should do now? I feel like all I've done is toss money at this thing and have gotten almost no where.




I have tried everything I can think of, even just for *****

 

[FIND]

I really wish I had the time to drive out there. After watching your other threads..... I just want to see this truck myself. I just can't think of what to do at all right now.

 

[Roadrunner777]

Are you getting 111 passing codes? If the engine is a transplant, have you checked to see the engine computer matches the engine versus being left over from the other one? 93 to 94 are some significant changes.

On the mystery connector, what is the color of the connector, and if possible, the wire colors going to it?

 

[BIGTREAD]

Okay. Just to keep the juices flowing I'll tell you about my 98eng into a 2000. The camshaft position sensor on the 98 is a two wire Hall effect system. The synch on the 2000 is a three wire variable reluctance sensor. The 2000 sensor fits nicely atop the 98 synchronizer. The 2000 computer don't like it much. I get what feels like a miss below 1500rmp under load, and am missing that edge an engine should put out at higher rpms. Mostly it idles okay now that I've cleared out all the vac leaks.

 

[XltExplorer33]

Have you checked all the vaccum lines?

 

[Ageman]

Have you checked all your vacuum lines.

 

[XltExplorer33]

I had a 92 ford explorer and my felt like it was missing and when I could give it gas it was sometimes delay. I changed the fuel regulator and I checked in the intake and had gas on inside there. So i would clean it out but it still kept getting gas inside there because it was all in the other vacuum lines. So would i would do is do a complete flush of vacuum lines and go from there.

 

[wood1]

So, sounds like you have hit pretty much everything. What were your compression numbers? Also, and I know this is pretty basic and you likely have done this already, did you pull plug wires to see if any individual cylinder had no effect when unplugged?

Cam worn funny, bent pushrod, ECM, er... you say you think it's a left-over '93 so it doesn't have EGR or it does? If it does there's a possible vacuum leak... think that's all I got... you must be very frustrated. I would have employed the BFH by now if I were you. Sorry to not be of more help, just trying to brainstorm a bit.

 

[huntman58]

On my 93 I fought a miss for over a year also. I could not find what was casing it at all and went threw most of what you have. In the end I changed out all vacuum lines and the Air tube from the air box to the TB. I also went back to a stock size MAF and air box from my 70mm MAF and Swiss cheesed air box once I did all of that I now have only a very very small miss at idle now and I feel its more vale and rings then any thing other. as for power yes it is down some and this shows on a vacuum gage when going up a hill or an over pass as it some times drops down to about 5 inches of vacuum with a steady speed held or no gas peddle movement. now is this some thing your fighting may be but it may be worth a try as vacuum line is not that expensive and normally they will not give you a code if the leak. Do not for get to check the lines also going to the heater controls or the passage side vacuum dash pot for the inside out side air control.

 

[mr cribb]

you must be very frustrated. I would have employed the BFH by now if I were you.

Ahh yes the BFH.... I love that thing!

The hose from the MAF to the TB isn't cracked or leaking of any kind? If you answered this question already I apologize for not paying attention.

This is all I can think of though.... I almost bet it is something retarded we're all missing.

 

[DasBaldDog]

Engine is not a transplant, just from some of the sensors the parts for a 93 match and a 94 do not.

I have checked all the vacuum lines a dozen times, used half a dozen cans of carb cleaner trying to find a leak, and am getting ~20 inches of vacuum at the tree. That and on the tree, I only have;
-Line going to FPR
-Line going to whatever the hell is on the airbox
-Line going to PCV
-Line going to brake booster.
All in all, not much to check.


I have checked the tube from the MAF to the TB atleast 3 times and cannot find any sort of crack or whole in it. (There is a hose going from a nipple on said tube to the oil filler spout but that looks like its supposed to be there).


Compression numbers were something like 1 of them was 125, two of them were 140 and the rest were 145.



That connector on the back of the engine that has nothing plugged into it, I can't see the colors of the wires but it is;
Black
Round
2 Prong
Female
Roughly 1/2 - 3/4 inch in diameter
Is on the same couple of inches of wiring harness that connects to the O2 sensors



The questions I am currently trying to ponder are,
-What is this wire connector
-Why doesn't the truck throw a CEL when I unplugged the Passenger side O2 sensor
-Could the ICM be a problem? Autozone has told me they can test it, but I am having trouble figuring out how to remove it.

 

[Roadrunner777]

There is a reverse switch on that harness that is a possibility, but I may be off by a foot. I am working from the wiring book, there are some other possibilities I am looking into. Do your backup lights work? I'll be under my ex this afternoon, see if I can do a visual.

 

[DasBaldDog]

I believe they do. Am at work abd the truck is at home, but I remember driving at bight and am pretty sure the reverse lights work.

 

[Roadrunner777]

Well, I just realized you are talking about a ranger, not an explorer. Ignoring that, let's go on. The passenger side O2 sensor goes about 12 inches to a 4 wire grey connector and another 6 inches up behind the intake manifold. At that point, it joins a larger harness. At least 4 other smaller harnesses join here too. One leg goes to the camshaft sensor. I think another goes down to the drivers side O2, and I can't tell, but probably goes on to my automatic transmission. It's tight back there, I am doing some of this by feel.. I saw no meaningful picture moments.

Is any of this familiar, and if so, where is your connector in relationship to it?

Are you getting 111 pass codes from the computer?

 

[DasBaldDog]

Getting 111's previously, but that was before I unplugged the one o2.


On the back of my engine at the tail end of my harness are 4 connectors.

Two for the o2's( they are white)
1 large white one for the tranny
And the mystery black connector.


Side question, on level ground in 4th gear, what is the lost rpm you can pull convincingly away in? I am trying to figure out if I just have a bad idle but the rest of the trucks performance is acceptable.

 

[DasBaldDog]

I don't think my engine has a camshaft sensor.

 

[MrShorty]

Why doesn't the truck throw a CEL when I unplugged the Passenger side O2 sensor

While we're checking things just for fun. Can you get any codes (besides a 111) out of the computer? Run the KOEO test on a cold engine and you should get KOEO 116 (ECT) and 114 (IAT) because the engine is cold. IAT is easy to unplug, I might even try unplugging it. Run the KOER test on a cold engine and you should get 116, maybe 114, 172 (O2 sensor will be cold and nonfunctional), and, if you ignore the BOO test and the goose test, 536 and 538 codes. Maybe even a 411 or 412 code if the engine is running rough during the test.

Should only take 10 minutes (and costs nothing). The idea here is just to see if the PCM can generate fault codes. I don't know if it will mean anything, but it might give us somewhere to go.

 

[DasBaldDog]

Okay.

Unplugged the MAF and the IAT, left the one O2 sensor unplugged and ran a KOER test first

Here's what happen.
Code 998
Code 113
Code 157

Repeat 998
Repeat 113
Repeat 157

Engine went to High/Low Speed.... initially trying to speed up, it initially stumbled and seemed like it would die for 1/100th of a second.

Then the CEL came on and stayed on. I left it running for about 3 minutes and the CEL never turned off.





Then I ran the KOEO test and got

Code 113
Code 157
Code 158
Code 543
Code 556
Code 122 (possibly 123)

 

[DasBaldDog]

Okay.

Unplugged the MAF and the IAT, left the one O2 sensor unplugged and ran a KOER test first

Here's what happen.
Code 998
Code 113
Code 157

Repeat 998
Repeat 113
Repeat 157

Engine went to High/Low Speed.... initially trying to speed up, it initially stumbled and seemed like it would die for 1/100th of a second.

Then the CEL came on and stayed on. I left it running for about 3 minutes and the CEL never turned off.





Then I ran the KOEO test and got

Code 113
Code 157
Code 158
Code 543
Code 556
Code 122 (possibly 123)

Code 543/556 Which I think are Fuel Relay/Pump codes may have something to do with my pulling the fuel relay to drain the fuel from the rail before I pulled the injectors.

The Code 122 may be from me swapping TPS sensors.

Have no idea what 998 is or why the CEL stayed on during the KOER test.

 

[DasBaldDog]

Okay....


The Mystery black connector near the O2 sensor connectors has two wires going to it.


It looks like there is an Orange wire with a yellow stripe and a Purple wire with a yellow stripe.


Don't know if that gets us anywhere.




Hooked everything back up, and unplugged the battery. Will drive it in about 10 minutes to see if it all comes back 111's.