Rough idle and no codes. Need advice!

[cnj]

Hi all.
I have a 2002 Edge 4x4, 3.0, Automatic. Truck has ~96K original miles. Runs excellent (except for rough idle-never stalls, just "stumbles"). No codes are being thrown. I have replaced the following with no improvement to the rough idle condition: Plugs, wires, cam synchro and sensor, PCV valve, fuel filter, air filter, IAC valve, throttle position sensor. I also cleaned the MAF sensor with specific MAF sensor cleaner! I also ran a few bottles of EFI cleaner through the tank, and had the fuel system cleaned w/Seafoam. It burns no oil whatsoever, and there is no oil in the coolant, and no coolant in the oil.
I gave up and took it to a mechanic. Compression ranges from 145 to 155 (good). Mechanic said it is missing on cylinders 4 and 5, and the problem is most likely that the valves/valve seats are bad (said it is a common problem on Ranger 3.0 motors). He recommended heads be rebuilt to the tune of ~$2700. I paid $4K for the truck 6 months ago, and have been fixing stupid little issues (paint peeling, airbag light on, burned out bulbs, etc). I won't put that kind of $$ into just the heads.
The truck is really clean, and I kinda like it, so I guess I am just looking for advice or guidance at this point. Any thoughts on what else the issue could be?
Should I: Run it till it breaks? Sell it? Throw in a motor? What does the brain trust think?????

 

[crokarlo]

I had the same exact problem. I replaced to maf. The ideal air. The cam position sensor. Turned out to be a vacuum lines. Get carb spray from your local car parts store and start spraying all your vacuum lines while your car is on and listen to when the rpm goes up. I did that and found that lines that were leaking. Trust me. Same problem! Also when you replaced all your parts did you reset your computer and let your car re learn ?


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[cbxer55]

When you replace electric components, the negative battery terminal should be off, so the computer is automatically reset.

 

[Rearanger]

Compression ranges from 145 to 155 (good). Mechanic said it is missing on cylinders 4 and 5, and the problem is most likely that the valves/valve seats are bad

What was the specific compression on #'s 4 & 5?

You're not getting misfire codes so it can't be that bad.

If you could get some fuel trim numbers that would tell you if vacuum leak.

How does it run above idle and under load, like up hill?

If you pull the #4 plug wire and the #5 plug wire (individually) does the idle get worse or stay the same?

 

[red2003xlt]

Check for a sticking fuel injector

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[Froggmann]

Check the resistance on the injectors. If your truck is Flex Fuel, run a couple tanks of E-85 through it--Ethanol is a much better cleaner than seafoam.

As stated before, also check vacuum lines very closely--a cracked vacuum line can have one chasing their tail.

 

[cnj]

Welp, following up on this. Took it to an independent shop, and then to the local Ford service dept. Both place's diagnosis was the same. Cracked head or cracked valve seat(s) on #4 and/or #5 cylinders. Not sure what to do. Probably a $2500 repair, but truck is worth $4K. Hmmmmmmm.

 

[55trucker]

Do you have your own compression tester?

Do a cold & a hot test...a leak down test would be of advantage as well.

another test is to pump compressed air via a spark plug fitting into each cylinder knowing that each is at top center on the compression stroke & to listen at the tailpipe for airflow (the exhaust valve/seat is more prone to fail than the intake) and also look in the coolant for any sign possible of bubbles.

offhand chance the head gasket has failed between the two cylinders?

$2700 seems a bit steep for two fresh heads & the labor to install,

a pair of over-the-counter exchange heads might be $400, the bolts another $40, a top end gasket set $90.....$2000 labor?

 

[cnj]

I had the same exact problem. I replaced to maf. The ideal air. The cam position sensor. Turned out to be a vacuum lines. Get carb spray from your local car parts store and start spraying all your vacuum lines while your car is on and listen to when the rpm goes up. I did that and found that lines that were leaking. Trust me. Same problem! Also when you replaced all your parts did you reset your computer and let your car re learn ?


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Thanks. Did all of this. Apparently no vacuum leaks. Went through almost a can of carb cleaner, and no change to idle. Yep, reset the computer by letting it sit overnight w/battery disconnected.

When you replace electric components, the negative battery terminal should be off, so the computer is automatically reset.

Thanks. Yep, did that.

What was the specific compression on #'s 4 & 5?

You're not getting misfire codes so it can't be that bad.

If you could get some fuel trim numbers that would tell you if vacuum leak.

How does it run above idle and under load, like up hill?

If you pull the #4 plug wire and the #5 plug wire (individually) does the idle get worse or stay the same?

Thanks. I don't recall what he said the compression was on 4 and 5, but for sure, 4 was the lowest.
Yeah, the mis-fire isn't bad enough to stall the truck, but it is not right, and that bugs the crap out of me.
The truck runs great right off idle, and has plenty of power (as much as a 3.0 Vulcan can have, anyway). Truck runs great under load.
When disconnecting the #4 or #5 wires, there is definitely a difference in how the truck idles, so I know those cylinders are firing.

Do you have your own compression tester?

Do a cold & a hot test...a leak down test would be of advantage as well.

another test is to pump compressed air via a spark plug fitting into each cylinder knowing that each is at top center on the compression stroke & to listen at the tailpipe for airflow (the exhaust valve/seat is more prone to fail than the intake) and also look in the coolant for any sign possible of bubbles.

offhand chance the head gasket has failed between the two cylinders?

$2700 seems a bit steep for two fresh heads & the labor to install,

a pair of over-the-counter exchange heads might be $400, the bolts another $40, a top end gasket set $90.....$2000 labor?

Thanks. I can do the work myself, but I don't have many tools any more. I don't really have the space or time to work on this kind of stuff with where I live and my job, unfortunately. Kinda got to rely on a shop at this point.

As to the cost, I agree. I can get remanufactured heads for ~$350, or brand new ones for ~$800, so looking into my options there.

 

[Blitz]

I know this thread is 5 years old but did the new heads fix your problem with the rough idle? The reason I ask is because my ranger has the same symptoms except now the reman heads are $550 and labor is $130 an hour

 

[Richard2000]

Hey Blitz did you resolve your miss issue? Mine occurs at idle with air on. I ran fuel injector cleaner and premium fuel and it went away, but returned later when I went back to regular fuel.

 

[Blitz]

No I have not gotten to the smoking gun yet on the rough idle. I have replaced just about everything possible. Do you want to hear something amazing? My brother has a 2002 Ranger Tremor that is only a few hundred off my Vin number so we basically have the same exact truck. His has 105,000 miles on it and mine has 85,000 miles on it. His has same rough idle. He was working on it one day and a screw dropped into intake and ruined his engine. He found a 2002 3.0 motor with 80,000 miles on it (Ranger Tremor again) so that is 3 Tremors out of the 6000 made that year. He installed new timing chain, water pump main seals, ect... before having it swapped with his motor. Guess what, It still idles with a stumble. So that makes all 3 engines have the same stumble. He sent his original injectors out to get cleaned and rebuilt and if that does not work then I would guess its the head issue. I personally will just drive it with the stumble and not spend the now $2000.00 plus head job. if I ever do decide to do it I will have my mechanic pull the motor and do everything at once and re-install. All gaskets, seals, chains, sprockets, pumps etc.. My Tremor is probably worth $10K right now so sticking $3500.00 in it will suck but in todays world there might not be a better option. As soon as he replaces Injectors I will shoot out the result. The old injectors did look horrible.

 

[O No 3.0!]

$3500? You should be able to get the heads done for under $2000.

 

[Blitz]

$3500? You should be able to get the heads done for under $2000.

I was planning on doing all the oil leaks and defects on the engine at one time.
1. oil pan gasket
2. main seals
3. water pump
4. timing chain and gears
5. valve cover gaskets
6. intake o-rings
7. valve cover gaskets
8 Heads
= guestiment = $3500.00 and I will have a new engine with 87k on it. I have learned that buying a 20 year old truck with low miles is a nice find but old man time is just as hard on the old girl as many miles are on a newer truck. For now I am just driving it and waiting for something to fail.