Hello All,

I have a 2004 Ranger Edge, V6, 2wd Manual. It has about 75k miles on it; I’ve owned it for about the last 8 months. Since I have owned it, it has had random engine troubles. Was really rare (Like once a month), and now it’s more frequent. What happens is, once the truck is warmed up, and engine starts to idle (700ish rpm). If it idles too long, say I’m at a stop light, and it’s a long one, 2-3mins. Sometimes, the engine light will start to flash, and the motor seems to run in its “safe” mode. I have restarted the truck and it starts fine, no issues after. I have even had it drive it in the safe mode to get out of a turning lane, and before I could pull over, the safe mode turns off and my truck drives like normal.

Now in the last 2 months, this has been occurring more often, (once every 2 weeks), engine will idle really ruff when it sits for 2-3mins, while warm. I have replaced all spark plugs, spark plug wires, and igniter coils. The engine idle and performance has increased, it’s been a lot smoother, but still having this random issue.

I am leaning towards an O2 Sensor malfunctioning, as once the truck is at temp, the o2 is not reading the idle flow right, and it thinks the motor is misfiring. I have no codes or CEL light up. I have had the CEL show up twice, and within 10mins of driving, it clears itself. I did check the codes, and nothing showed up.

I’m at a loss and I don’t want to just throw money at a problem, if it’s not the cause. Any ideas, hints or information would be great.
Thanks.

 

Probably not O2 sensor issue, you would get a steady CEL for that as it is part of the emission system.

Run a can of Seafoam in the gas tank to clean injectors, that always helps my '94 4.0l, I do it once a year.

At idle the computer runs the engine rich, that is normal, not sure if computer even uses the O2 sensors at idle.
Flashing CEL usually means bad misfire is occurring, the unburned fuel flowing into the Cat Converter can damage it over time, so CEL Flashes.
This should leave a History code, but not always.
CEL being on almost always stores a code in History.

From what you have said the CEL comes on but engine never runs rough???
is that correct?
Or is there a vibration at idle, misfires?

What do you mean engine seems to run in "safe mode"?
What are you seeing or using to determine that?

3.0l has a Cam Position Sensor(CPS) in the old distributor hole, the syncro shaft on these have bushings that wear out at about 80k miles.
The CPS controls the injector timing, if timing starts to drift off at idle that could cause misfires.

The EGR system has a computer controlled vacuum switch(EGR Modulator) to open the EGR Valve.
The EGR valve should only open when RPMs are up and engine is under load.
If EGR Valve opens a bit at idle, you will get misfires, if EGR modulator was leaking vacuum thru to EGR Valve you would notice this more at idle as that is when vacuum is highest.
After engine is warmed up and idling, remove the vacuum hose on the EGR Valve, it should have no vacuum on that hose, if it does then EGR Modulator is most likely leaking.
BUT.........it could also be the DPFE sensor going bad, DPFE sensor tells computer if EGR valve is open and how much it is open, stock Ford DPFE sensors often start failing around 60k miles, failing DPFE sensor almost always turns on CEL.

 

I havnt run Seafoam through the tank yet, just SLP Injector Cleaner, I’ll give that a shot to help clean things up.

So my CEL, normaly flashes when it starts to idle really ruff. If I try and drive it when flashing, and the ruff idle, the truck is really slow and sluggish. The other day, this happened at a red light. As I was getting off the road to take a look, the truck just started to drive like normal.

It wasn’t a slow transition from ruff to steady, it happed at about 2700 rpm. It felt like a switch got hit that made the engine run like normal. As soon as that happened the CEL Stopped flashing and everything was normal.

I have had the CEL stay lit twice, but never long enough for me to get a computer on it and check the codes. By the time I got to the store, the CEL was gone, and codes cleared.

 

that injector cleaner is fine, no need to do seafoam now.

So there is rough running, that can cause flashing CEL, but only while the misfiring is happening.

Codes can't clear themselves.
CEL being on means a code or codes are in active memory, if CEL goes off then these codes have been moved to Historic memory, and they will stay there, for, I think 100 restarts of computer, or they can be cleared with code reader.
How are you getting the OBD II checked?
Operator may be clearing codes by mistake


If it happened at higher RPMs as well, and it was sudden start and sudden end, I would suspect ignition system as you did.
Since you have replaced the coil already then only thing I can think of that could cause it would be the CPS, along with fuel injector timing it also plays a part in spark advance timing.
You should have the 2 wire CPS('98 and older used 3 wire), it can be tested with engine running.
You need a volt meter, AC volts, and a couple of straight pins(like used in sewing)
Pierce each wire with pin, far enough apart so pins can't short together
Clip volt meter to pins
start engine, you need access to throttle so you can vary RPMs so remove that cover piece before starting.
Voltage should vary by more than .01vAC as you change RPMs and remain steady at set RPMs.


There is a longshot issue that effected 3.0l engines around your year('04), they have floating(bad) exhaust valve seats, this caused on again off again issues
TSB here: http://ww2.justanswer.com/uploads/s4...b05-26-03.pdf/

 

For the CEL Codes, I just went to a local O Riley’s auto parts, they plugged it up and didn’t see anything (CEL was out by the time I got there), and I can go back and see if it’s in the history still. It wasn’t in the active.

The sudden start only happens when coming from a long idle tide after the truck is at running temp. If I start it up and let it go from cold. I let it run about 25mins, had no issue (after I did the coil and wires/plugs). So I thought it was all good, but issue still happens. This is why I was thinking 02 sensors, but if the computer ignores them at idle then it can’t be that.

I have notice no problems when driving, I drive about 30miles a day, and 90% of the time, no issues. I wish the CEL would stay on, give me an idea where to look. I suspected a vacuum leak, but if this was true, I would expect more problems then what I am seeing.
I’ll check the CPS sensor when I get home. The sticking EGR value sounds like a cause too, if it gets stuck open at idle, the longer it sits the more bogged down the engine will get. I normally cruise at 1500-1800rpm. Is the EGR open at these levels?

 

So, after reading these posts, and investigating, it turns out the 3.0 V6 model does not have an EGR system.

Atleast Im not going nuts, I probably spent a good 20mins looking for it under the hood. Found where it should be, but no components installed.

So, this just leaves checking the CPS (Cam poisition sensor).

Is there anything else that would cause these issues?

Truck runs good, if I let it idle for 2-3mins, it starts to misfire, No codes stored in active memory(CEL goes off as soon as misfire stops).

I have a code reader coming tomorrow, so I'll dig through the memory and see what it says.

Im at a loss, CPS makes sense, but a leaking egr valve sounded so much better.

 

Whats the MPG like?

Wondering if you have a sticking injector, so engine is getting to rich at idle, O2 sensors probably wouldn't see this, I believe at idle and WOT(wide open throttle) the O2 sensors are ignored.
But I would expect a puff of smoke out the exhaust when you did get RPMs back up.

Hopefully you will find some codes in history

 

So far MPG been decent, was getting 20 in the city. About a month ago I get new tires, 32" so I havnt been able to really see a change, but as far asI can tell MPG is the same, if not a little better. Able to cruise at lower RPM at higher speed with the increase in tire size.

I think I need to just wait for the codes, may be over thinking the issue now, Im dreading the idea that I have to replace the heads.

 

Your year 3.0 does not have an EGR, but the earlier 3.0's did.

 

Using this site:

Calulators from www.4Lo.com

Roughly, a 32 inch tire is almost equal to a 285/75R16. If we use a stock size tire for calculation (say a 245/75/R16) for your setup, your adjusted speed is as follows: If the speedo shows 55, you are actually driving 59 MPH with the 32 inch setup. This again is assuming you have 16 inch rims, and increased the tire size.

And the larger tire size equates to a heavier tire combo, increasing the load to move it, so MPG should drop slightly.

 

So I checked the codes last night, and I had nothing stored. The truck did missfire the day before so I know it has happened recently.

I was a little surpised to not see anything, but a little relieved.

So Next step, I have a nice 3 day weekend here, things to check/fix, let me know if Im missing something Simple.

Ohm Check Each Fuel Injector, see if one is malfuctioning, (was told if these go bad, it will cause the misfires, but will not throw a code).

Volt Check Cam Position Sensor (worth checking, but I dont think it will be bad, would expect codes if the sensor was malfunctioning)

Clean/Replace IAC Valve.

Clean MAF

Compression Check (though since no codes have been thrown, this seems like a last ditch check)

My friend who owns his own mechanic shop seems to feel I have an injector that is having some issues, Im tending to agree with him. From everything Ive read here, and the research done, Im at a lost.

 

Ya, I expected a slight drop, but with how I drive on to/from work, I have been able to cruise at a lower RPM, with an increased MPH. I love my manual truck! I dont have much start and stop, so added weight isnt a big deal. Going off of my miles traveled/gallons pumped. Nothing has changed with the new tires. But, since miles are off, seems I got a sligth increase. I'll crunch numbers and get estimated mileage later. It hasnt been a priority :).

I also went from the 16x7" rims to 15x8" rims with the BFG Allterrain KO 32". Was like 70$ more then trying to get a "32" tire" on the 16x7 rims.

 

Cool setup with the tires. I inherited a set from my son, who had them on his Toyota 4Runner. They are 31 inch. I wish however I kept my old rims and tires, as these 31's are noisy, and somewhat of a paristic (spelling?) drag, or at least it feels like they are.

Let us know how the injector inspection/testing comes out. I'm interested as to the what the outcome of your problem ends up being.

 

Will do for sure, been trying to figure this out for almost 2 months now. Its starting to get worse is why Im starting to stress.

As far as the tires, I doubt they are creating much drag, may be more friction with the ground or overall weight compared to the old tires. If there under inflated, that could really slow ya down too. Less air means more surface area where the tire contacts the road. Good for traction, bad for mpg :

 

I do keep them on the higher side of the recommended inflation that's posted on the tires. That helps, but these knobby style tires are just noisy.
My son has a 1995 Toyota 4Runner 4x4. He raised the body 3 inches, so these 31's where no longer "cool looking" (as he put it) on that vehicle. So 33's went on. Now he needs a rope ladder to get into it. Since dad paid for the 31's he had on it, dad ended up with them for the Ranger, because I was ready for a new set, and mom thought it would be a great idea to simply use the sons tires on the Ranger.

New Rule: Don't listen to mom (and son) when it comes to tires and my Ranger.

 

Well, things are always interesting with my truck. Thursday Night, I got home, check codeds, and nothing.

I checked my fuel injectors on passenger side, the driver sides were blocked by throttle body and intake. I cleaned iac, maf, air filter. Put everything back together. Started it up, went filled up the truck, came back home, and it started to idle ruff and misfire at the house.

I plugged scanner right in, and wala, I got codes finally.

P0304, and p0316. Cylinder 4, and misfire at start up.

So it doesn't seem to retain those misfire codes for long, but seems to do it while the engine is hot. I was able to check cylinder 4 fuel injector with a ohms meter, it checked out. I pulled the plug, it did look a little fouled out now, gapped a little tight so I brought it back to the 44thou. I think I may have tapped it while replacing it? I did ensure the spark plug and wire were firing.

Right now, Im at a loss. Its either I pull the intake, replace injector. Test it out.

Or do a compression check.

Any ideas or suggestions? Injector is 50bucks, not terrible, but thats yet another $50 replacement on something that may not need it.

 

Are you sure the plug wire/coil of the coil pack are good that serve that #4 cylinder?

 

Well, I swapped out the fuel injector, it idled fine finaly no load. I drove to work this morning, about 30mins of driving. Pulled up, let it idle, after about 3mins it started to misfire again. I left my code reader at home so I cant verify its cylinder 4 again, but Im pretty sure it is.

So I have a new plug, wire, igniter coil, and now fuel injector installed.

Only thing I can see left to do is the compression check, as I have this gut feeling my head is bad. IF I had a cracked valve or seal, I would see it more then just at idle.

I'll post results of the compression check when I get to it, probably wont be untill Tuesday/Wednesday.

Bucko,

I did check to see if my spark plug/wires were firing by pulling the plug, hooked up the wire and started it. I had a good spark which was expected.

Id like to belive if it was a plug/wire, id have "worse" problems. The drive to work this morning was smooth, no isues/lag/bogged down acceleration.

Any advice is very welcome.

 

Sounds like you're doing all the right tests...if the injector is clean (good spray pattern), the cylinder's firing, then compression or valve sealing is the next step.

Good luck!

 

Thanks, Just dreading the outcome that I know is coming. Every post ive read with my issues, all point to the TSB with valve recession on the exhaust valve. Which will mean brand new heads.

Just trying to find the best replacment, as well as figure out if I can get these heads off with the engine still installed.

God knows Im going to have to pull my tires off and "lower" the truck so I can work in the bay. Had to climb into my engine bay to get the upper intake off this weekend, must have been a sight lol.

The only part of the entire swapping heads part that makes me nervous is dealing with the timing chain components. I have replaced chain tensonors in the past, but never had to pull the heads/cams, so it was always, make sure nothing moved, and put it back together.

I know i can do it though, just may lose some of my T-day vacation.

 

TSB here: http://ww2.justanswer.com/uploads/jm...sb05-26-03.pdf

Compression test on all cylinders would be a good choice.
All spark plugs removed, throttle plate opened

Yes, heads can come off with block still in vehicle.
No timing chain to deal with, cam is in engine valley and lifters and push rods are used, 3.0l vulcan is OHV, not OHC(over head cam)

Good info here on 3.0l vulcan engine: http://www.therangerstation.com/tech..._0-build.shtml

 

RonD!

Thats great news! I used to own a V8 Mustang, SOHC, 16 valves on each head. I replaced the valves on that and it was time consuming, chains were just as tricky with restricted space. I learn by doing and I just keep picturing that head, but with 12 valves. You just made my day. So it really is just pull cover, and unbolt the head.

Head swap just lost like all difficulty in my eyes.

Thanks! Will do my compression check and leak down after if I do have an issue.

More to come!

 

Well I did the compression test, Got the following
#1 170
#2 165
#3 165
#4 120
#5 160
#6 165

I put a little oil in #4 and it raised up 20psi, but still low. It was also on a cold engine. My mechanic friend (owns his own shop) says oil on the cold will raise the compression no matter what, so its not really telling me anything. Reading back I probably should have done it on a hot engine, but really didnt want to burn the crap out of my arms getting to cylinder 2 and 3.

When my truck was misfiring really bad yesterday, you could hear it through the exhaust, he suggest this is a tell tail sign that its leaking into the exhaust.

So as far as I can tell, everything is pointing to the recessed valves on the head. I will start pulling everything apart tomorrow morning. Found heads from O'rileys for $180, looking to get a discount through my friend hoping to bring it down to 300ish for a pair.

I'll let everyone know what I find on the head tomorrow.

 

#4 has a bad valve or seat, even at 140psi it is right at the 15% threshold, and other cylinders would be higher with oil added so it would be closer to 25% difference.

Having done it both ways when I was younger, I can say I have never found a warm compression test telling me more than a cold one.
Purpose of the test is to get an average compression number, so the actual numbers aren't the point, the difference in the numbers is the point.

If you raise the PSI by 10 or 20 across the board you still get the same conclusion

 

So, Aftermath of the job, I got both heads off, replaced both of them, and now my ranger feels like new. In fact I believe it is now running better than I have ever felt it, given that I bought this truck about 6 months ago, and it was already having issues, but was very rare in occurrence at that time.

Both heads had recessed valves, and the #4 cylinder was the worst as expected. That cylinder head had about ¼” to 3/8” of recession into the head. The new cylinders were all protruding from the head when fully seated. Someone with no mechanical knowledge could go, I see a problem here, when comparing new to old.

I took pictures during the tear down; I’ll post up later if anyone is interested.
Things to note, if anyone reads this thread that plans to do this rework, who like myself, was the first time doing this task.

#1: Buy the Fan Clutch tool, or ensure you have a away to remove your fan/shroud. This will make getting to the 3 bolts holding power steering pump and ac compressor to the head off. Of the entire job, these 3 bolts gave me the biggest problem. Probably a good hour to tear it down, another hour and a half to build back up. I had one hell of a time getting the bolts to line back up for build up.

#2: Be ready for a big mess. Drain the coolant first, and make sure you got rags ready as you remove intake/heads for residue.

#3 Have a large ½” breaker bar or larger ready for head bolts, or a functional impact wrench to remove them.

#4 Best way to get to exhaust/header bolts is through the side wheel well, take the front wheels off.