I'm a newbie!

I love my Ranger. I'm quite impressed with the power and durability. I'm ticked at Ford for stopping production.

I have searched my problem and could not quite narrow it down. I have also tried several remedies with no improvement. I'm hoping one of you or some of you can help narrow it down to a specific item.

2004 Ranger, 4.0 liter, 4x4, 131,000 miles, runs great above idle.

Problem: rough idle, idles at about 750 rpm's. If i raise the rpm's to 850 and up, smooth as silk.

The truck did this a few years back. Not quite as rough and it went away by itself.

Engine light came on this time with P0303 & P0316 codes.
I have replaced: plugs, wires, coil pack. I know that the #3 plug is sparking quite well. the #3 injector is getting signal to spray not sure if it is. I have 4 O2 sensors and I believe I tested them correctly (passed). The passenger side upstream or pre cat sensor has not been tested yet. Had to rent a tool and will do that in morning. I slid a piece of aluminum roof flashing between the crank position sensor and the crank pulley. Not a noticeable difference. While at idle (750 rpm's) I pulled each (#3,2,1,) (one at a time) injector wire plugs off the injectors. No noticeable difference. I pulled the vacuum line off the egg and operated it with a vacuum tool. Seems to be working fine. Sprayed carb cleaner around on vac lines. No engine surge.



Not sure what to do next! I will replace the crank sensor tomorrow because it's a cheap experiment. Unless someone tells me not to.

Please help!!!

 

I know the 3.0 liter engines had some problems with valve seats but not aware of the 4.0 liters having this trouble.

 

I do know that the V6 4.0 liter motors have a tendancy to have the intake manifold fasteners to loosen after time. I donnot know if this is applicable to your V6 3.0 motor.

 

Also changed all o2 sensors, crack sensor (sorry thats my thong) I meant crank sensor, checked all vacuum lines no leaks.

I'm at a loose! help if you can!

Thanks!

 

While you were doing all this, did you disconnect the battery negative cable so the computer could wipe the fuel trim data and whatnot?

If not, disconnect the cable for a few minutes then reconnect. If you have an automatic transmission, there is a procedure to be followed for the computer to re-learn things - that procedure can be found in this forum if you search for it. If you have a manual transmission, just drive it around like you normally would and the computer will re-learn everything.

Also, after having the cable disconnected, you'll want to re-check for codes...

 

Fury

Thanks! I disconnected the the negative terminal for at least 15 min two times during all the changes but did not drive the truck just started it up to find the rough idle is still there. This morning I was talking to my dad and asked him if I needed to give the computer time to readjust. We did not know so I tried to search it but didn't know exactly what I was looking for until now.

Thanks again

 

Seeing as how the computer is unhappy with cyl #3, concentrate your trouble shoot with it.

Listen to #3 injector to determine if its "click" sounds different than the other injectors.
If it does, do a resistance check, it should measure between 12-16 ohms & all injectors resistance should be closely matched.

If thats ok, pull #3 spark plug & do a read on its internal ceramic deposit loading, looking for carbon deposit loading (signs of a leaking injector), or signs of a lean mixture, (white or blistered ceramic), which would suggest the fuel injector giving a lean shot in that cyl.

If the plug read checks out ok, do a compression check on #3 to see how its doing.

If compression checks out but the plug read doesn't, if it looks to be carbon fouled, do a fuel pressure leak down test to see if maybe #3 injector is dirty & weeping fuel into the cyl.

If the plug read indicates a lean mixture, it would indicate a lean injector fuel shot.

So if you have indications of an injector squirt problem & the injectors resistance & compression checks out ok, give her a 20oz dose of Chevron Techron Concentrate Plus at the pump before filling up (so you get good mixing), with Chevron, Texaco, CalTex, or Shell gas, which have PEA in their fuel ad pack, so the 20oz Techron dose will raise the PEA treat rate 10X above pump gas alone, then run most of the treated tank out & see how it goes. If its better but not cured, do a second Techron treatment & see how it goes. If its still better but not completely cured, maybe consider doing, or having a pro injector cleaning service done.

More thoughts for consideration, let us know how it goes.

 

Pawpaw, Thank you for the help!

I reset the computer overnight and then drove the truck to work (25 miles) It seemed fine at speed but always rough when the engine gets back to idle. After work I took a stop & go route and it bogged down on me. I had stopped for a light and then started up again. It felt mushy didn't spit and sputter just would' go like normal. After about a block it went away and didn't come back. Just rough idle at each stop.

Tonight I removed the 1,2 & 3 injectors, making note of 3. I then hooked jumpers up to a battery and touched the inj. terminals. It clicked and some fuel came out. Not sure if it means anything but fuel didn't come out of 2 or 1 when i tested them. My multi meter may be bad because at first it came up to 16.??? then settled at .496 for 3 & .483-2, .49?-1. I then placed #3 inj. back in the #1 hole. Put the others back in buttoned the rest up and started it. Still rough! I only let it run for 10 min. then shut it off and disconnected the B-. I f the light comes on again we'll see if its for 3 or 1 and that should eliminate another possibility. While running I also disconnected the cam sensor for a few min. to see if that made a difference. No such luck!

I didn't read your reply until I came in after doing all that so I couldn't do as you request.

As for the plug. The computer gave the same code with the old and the new plug.

I did a compression test a few days ago and 3 was 164 and 1 & 2 were 160 & 162. Note: I used my comp gauge a few years back and discovered it was reading low and I believe it was 5 pounds low but can't swear to it.


At one point during the comp test I compared plug 3 to plug 1 and they looked identical. I was searching for some clue as to what was happening in cyl 3.

Last, the techron, I will get some tomorrow and start the process.

While 3 inj was out I thought I could see carbon build up down in the hole so I gave it a few squirts of carb cleaner.

Sorry for the lengthy post but I'm trying to give as much info as possible.

Thanks!

 

I had another thought/question.

If the timing belt/chain was loose wouldn't the error codes be more disburse through the cylinders? Also, Wouldn't there be issues throughout the RPM range and not just at idle?

Trying to eliminate another possibility.

 

Search "symptoms of a loose timing chain" and some of that sounds close to my problem.

Any chance this could be it?

 

Swapping the injectors did not repair the issue. Rough idle and P0303 & P316 came back.

Added the double dose of Techron concentrate. We shall see!

Any other thoughts?

 

Right now, with the symptoms & clues you've posted, the computer being unhappy with just the #3 cyl, the problem coming & going, the results of your compression & fuel injector swapping tests, ignition parts replacement, its kinda sounding like Combustion Chamber Deposit Flaking (CCDF), which is combustion chamber deposits flaking off valves, piston crown or head, getting lodged in the intake or exhaust valve seat & causing mischief & if so, the Techron along with part of Fords 4.0L decarb proceedure of high rpm/spirited daily driving, of 3600 rpm 3 mile runs, may tidy things up.

The other thought I had was maybe the #3 fuel injector electrical feed, or a computer ground switching driver problem.

Maybe the injectors electrical connector pin/socket, or its wiring has an intermittent problem. So, if no joy with the Techron, maybe do a KOEO voltage feed check at the #3 injector connector, along with a wiggle test, to make sure there isn't an intermittent problem. Seeing as how it seems to run fine at higher rpm, this is kinda a long shot.

A noid light hooked up to the #3 injector electrical connector & watching to see if its blink rate changes or goes missing at the rough idle rpm, might be worth considering.
Most autoparts stores have the Noid lights in their "Loan-A-Tool" program for a refundable deposit.

Edit: With the computer being unhappy with just one cyl, I don't think the timing chain would likely figure in.

Let us know how it goes.

 

Have you tried a Seafoam treatment?

 

thanks for the help

 

Tried the techron treatment and it did not work. No change still a rough idle and no ideas anymore.

Any other suggestions?