3.0 rough idle and missfire

[clayborne]

Hello all and thanks in advance for anyone willing to read the long-winded breakdown below and comment anything they deem helpful. I have a 2006 ford ranger 3.0. It was idling rough intermittently starting about 3 weeks ago but now has been doing it consistently. Pulling the error codes, I get the following codes consistently:
1. P0303 (misfire in cylinder 3)
2. P0316 (misfire detected on startup)
3. P1000 (System Redieness test not complete)
What I have been able to rule out:
1. Vacuum leak: I have hosed that engine down in carb cleaner and the idle though rough as all get out does not change
2. PCV valve: replaced the heated PCV valve on the driver’s side no change as far as I can tell there is not one on the passenger side
3. Spark Plugs/wires: have changed the plugs and plug wires with no change
4. Coil pack: have 3 brand new coils a motorcraft a duralast and a screaming eagle same idle with all 3
Not wanting to throw anymore money at the problem (PCV valve was 80$ not to mention the price of the coils) I was planning on doing some test this weekend to rule some stuff out.
1. Compression test on the number 3 cylinder as I have heard the valve seats are an issue with the 3.0
2. swapping out the #3 injector with the #1 injector and seeing if the problem moves to the number 1 cylinder
3. Renting a fuel pressure gauge to ensure I don’t have a low-pressure problem.
4. checking to see that the purge valve isn’t stuck open
Any other tests you guys could recommend would be helpful or any advice in general. I have read that bad gas could be a culprit so I put some injector cleaner and 98 fuel in it and have almost run a whole tank through it so I am not sure if that would be the case.

 

[rusty ol ranger]

Sounds like cylinder 3 is the issue.

You changed the plug so youre down to either injector or compression.

Id do compression first because its eaiser then pulling the injectors, even though its more likely to be an injector

 

[clayborne]

That was the exact route I was going to try. I am praying it is an injector and not an issue with the rings or the head. I purchased the truck 3 months ago for a hefty sum of money because I live in the south and it is a 4x4, but it ran smooth as silk and the body was in fantastic condition so I felt it was worth the asking price. The motor, however, is pretty high mileage so any of these in my mind is just as likely. Thank you for your input sir it is kindly appreciated!

 

[rusty ol ranger]

That was the exact route I was going to try. I am praying it is an injector and not an issue with the rings or the head. I purchased the truck 3 months ago for a hefty sum of money because I live in the south and it is a 4x4, but it ran smooth as silk and the body was in fantastic condition so I felt it was worth the asking price. The motor, however, is pretty high mileage so any of these in my mind is just as likely. Thank you for your input sir it is kindly appreciated!

How many miles?

As much as it pains me to say (im a 2.9 guy, so complimenting a 3.0 is against my religion lol ) they are good engines. They live forever. I would bet pretty heavily against it being more then an injector

 

[clayborne]

How many miles?

As much as it pains me to say (im a 2.9 guy, so complimenting a 3.0 is against my religion lol ) they are good engines. They live forever. I would bet pretty heavily against it being more then an injector

200,330 showing on the odometer. I ordinarily wouldnt have invested in a vehicle with that many miles but the carfax showed regular maintence so I felt relatively safe in doing so.

The 2.9 is a great engine! the 88 broco II i drove for 20 years had one and it was on up there in mileage and never gave me a lick of trouble.

 

[rusty ol ranger]

200,330 showing on the odometer. I ordinarily wouldnt have invested in a vehicle with that many miles but the carfax showed regular maintence so I felt relatively safe in doing so.

The 2.9 is a great engine! the 88 broco II i drove for 20 years had one and it was on up there in mileage and never gave me a lick of trouble.

My 1st 2.9 went well over 300k with the original water pump, alternator, wholt nine yards. Matter of fact that alternator is on my current 87 ranger lol. Only time it ever quit was when the TFI went.

My only qualm with a 3.0 over a 2.9 is the fact the ones ive driven have felt completly nutless compared to a 2.9. But that said they are alot less quirky then a 2.9.

200k on a 3.0 thats been maintained wouldnt bother me a bit. I owned a 3.0 aerostar for a while that was pushing 200k, it ran perfect. The rest of the van was garbage though. A guy i knew needed money so i bought it for 500 bucks. I literally tried to kill that thing....and couldnt. It almost killed me one night when i had the cruise set at 60, someone pulled out infront of me and it wouldnt cancel. I hit the brakes it just downshifted and kept pushing lol.

 

[clayborne]

I only did compression check on the left bank and I dont think the numbers look good
1-125
2-120
3-100
not sure where to go from here. I would think if 3 months ago when I bought it if it had compression issues it wouldnt have ran very welll but maybe there are things a seller can do to hide it. I read that the engine cold should be around 120-130. I feel completely devastated.

 

[Dave18]

I'm in a similar position with my 3.0... I've had a gradually worsening rough idle for the last year or so (mine is a 2002, 230k miles). I've also ruled out the ignition side (new motorcraft coilpack, plugs and wires), and have new fuel injectors on the way. I tested the fuel pressure and changed the fuel filter, so if the injectors don't have an effect that rules out the fuel side too. After reading about the recessed exhaust valve TSB...

04-06 3.0 question

I just bought a 06 stx 3.0 its at 122k miles now. I read some people had issues with the valve recession. Is that all 3.0s for 04-06 or just a certain batch?! If you have that year with high miles let me know. Also it seems this should be on the 3.0 technical link above about the valve recession?!

www.therangerstation.com

I'm coming around to the likelyhood that my engine has this issue. On mine it's cylinder #4, with a compression reading of only 75psi... Although this isn't as bad as it sounds since the test was performed at 8300 feet, I was calculating a target compression closer to 100psi. I'll get the injectors installed this week and see if that makes a difference, otherwise I'll be shopping for new heads.

Sounds like this really should have been handled as a recall back in the day, had Ford been responisble about it...

 

[clayborne]

I'm in a similar position with my 3.0... I've had a gradually worsening rough idle for the last year or so (mine is a 2002, 230k miles). I've also ruled out the ignition side (new motorcraft coilpack, plugs and wires), and have new fuel injectors on the way. I tested the fuel pressure and changed the fuel filter, so if the injectors don't have an effect that rules out the fuel side too. After reading about the recessed exhaust valve TSB...

04-06 3.0 question

I just bought a 06 stx 3.0 its at 122k miles now. I read some people had issues with the valve recession. Is that all 3.0s for 04-06 or just a certain batch?! If you have that year with high miles let me know. Also it seems this should be on the 3.0 technical link above about the valve recession?!

www.therangerstation.com

I'm coming around to the likelyhood that my engine has this issue. On mine it's cylinder #4, with a compression reading of only 75psi... Although this isn't as bad as it sounds since the test was performed at 8300 feet, I was calculating a target compression closer to 100psi. I'll get the injectors installed this week and see if that makes a difference, otherwise I'll be shopping for new heads.

Sounds like this really should have been handled as a recall back in the day, had Ford been responisble about it...

I hate to hear that for you brother! I went for a short test drive today and she threw another code this time amongst the #3 misfieres there was an P0231 was pinging and running so poorly I was wondering if I was going to make it home. The first round of codes had an P0171. Maybe its low compression combined with a failing fuel pump or clogged filter for me. I will test the fuel pressure and decide where to go from there.

 

[clayborne]

Just checked and the fuel pump is putting out a steady 65lbs so I am back to square one.

 

[Dave18]

I haven't looked too far down this path yet but I get the impression changing the heads is fairly do-able if you buy a set of assembled remanufactured ones... I'm hoping that is the worst case for me. If the fuel injectors don't help I think I'll have to take it to a shop for some advice - I'd just want to make sure the rest of my 22 year old block is in good enough shape to justify the cost of new heads.

 

[rusty ol ranger]

I only did compression check on the left bank and I dont think the numbers look good
1-125
2-120
3-100
not sure where to go from here. I would think if 3 months ago when I bought it if it had compression issues it wouldnt have ran very welll but maybe there are things a seller can do to hide it. I read that the engine cold should be around 120-130. I feel completely devastated.

100 is a bit on the weak side. But its still pretty close to spec (the lowest cylinder should be no lower then 20% of the highest)

Repeat the test and squirt a tiny bit of oil down the plug hole before testing. Oil helps seal the rings and gives you a closer reading to what running compression would be.

You also need to disable the ignition during the test and hold the throttle open.

If its still low, i would also run a leakdown test. This will tell you if its rings or head/valve issues.

That being said if it does turn out being a head issue, its probably a valve or a gasket. If it were me (at that point) id just take the head to a machine shop, have it magnafluxed (checked for cracks) and trued up (i just had this done to a tractor head, costed 140 bucks) and replace the valves/springs/keepers on that cylinder.

Be much much cheaper then buying heads.

 

[clayborne]

100 is a bit on the weak side. But its still pretty close to spec (the lowest cylinder should be no lower then 20% of the highest)

Repeat the test and squirt a tiny bit of oil down the plug hole before testing. Oil helps seal the rings and gives you a closer reading to what running compression would be.

You also need to disable the ignition during the test and hold the throttle open.

If its still low, i would also run a leakdown test. This will tell you if its rings or head/valve issues.

That being said if it does turn out being a head issue, its probably a valve or a gasket. If it were me (at that point) id just take the head to a machine shop, have it magnafluxed (checked for cracks) and trued up (i just had this done to a tractor head, costed 140 bucks) and replace the valves/springs/keepers on that cylinder.

Be much much cheaper then buying heads.

Machine shops are going the way of the dinosaurs here in middle TN but I know of one an hour away with a good reputation. I will squirt some oil down in there and see if my brother can come and help as that sounds easier with 2 people. Again thanks for your advice sir!

 

[rusty ol ranger]

Machine shops are going the way of the dinosaurs here in middle TN but I know of one an hour away with a good reputation. I will squirt some oil down in there and see if my brother can come and help as that sounds easier with 2 people. Again thanks for your advice sir!

No problem

 

[Dave18]

So if the issue is the recessed valve seats per TSB 05-26-3, is there anything a macine shop can do about that? Or would we need new heads with hardened valve seats? I don't think I understand well enough what the valve seat looks like to tell - is it just a part of the same iron casting but with some form of surface hardening?

I may be getting ahead of myself since we don't know that's the issue in either of our cases, but just trying to understand better how things work.