I ask an auto mechanic about my rangers idle during high rpm. It sound like there is a misfire on one of the cylinders when the rpm is raised to 3,800 and up. The mechanic said its normal for this kind of engine since it's not designed to run on high rpm and he also experienced it on his own ranger. No code nor engine stops, just a misfire like symptom when engine idle is rev up to 3800 rpm. Truck runs fine and no others sign of trouble.

 

what are the symptoms? shaking/rattling? sounds?

 

Engine will shake. Shake will stop when you ease the pedal and rpm drops below 3800 rpm.

 

Spark plug may have too big of a gap, or may have worn down to a larger gap.
Could be a spark plug wire or even a coil heating up at that high of an RPM.

At high RPMs the recovery time for the coil gets critical, i.e. voltage doesn't have enough time to build up and jump the larger gap.
Smaller gaps require less recovery time, but larger gaps are better for cold starts and lower RPM performance.
3.0l lists 0.044 as the average gap
If you will be running more at highway speeds and higher RPMs then I would set 0.041 to allow better recovery time.
If you were hauling loads and needed better low RPM performance then set 0.047.

Factory spark plug gap is not optimal, it is average for general use, you should change it for your primary use, +/- 0.005 is about as far as you would want to go.

 

3800 RPM is not that high peak power is 4750 RPM on your year now that would be seen under load which there are different engine parameters for that but the blanket it doesn't like high rpm is BS for this issue. Also is it auto or manual?

 

I will check the gaps soon, it's not giving me any trouble for now. It only has 67k miles and the truck has automatic transmission. It's not being use too much, 3 miles/ day- 4x a week use only.

 

Automatic has a rev limiter in neutral the stutter/misfire you hear is the PCM cutting fuel and retarding timing to keep it from blowing. Shouldn't be an issue its programmed to do that. I had the issue when i swapped my manual in since is till run the auto PCM and it always thought it was in neutral. I had to raise mine up so it would actually accelerate.

 

So I'm good with this condition, no need to check my gaps for now.
Thanks for the clarification. This is my first Ranger and I like.
I'm studying now about giving it a cold air intake. I read some forums that it helps the engine a little bit by having more air intake. What do you think about this?

 

The 3.0 rangers have a pretty good intake setup i have an aftermarket adapter to allow for a cone filter and am actually probably going to swap it back to the factory air box as it doesnt provide a noticeable gain. The heads are the bottleneck on these motors so unless you plan to port/polish the heads and upgrade the rocker arms/ cam it won't really breathe any better with just the intake it still gets bottled up in the intake/head. Port/polish is really the only way to open them up short of forced induction.

 

Yes, I missed the part about reving engine in neutral(0 on speedometer), rev limiter would start cutting engine at around 3,500 on most models.

By the start of fuel injection(mid-80's) pretty much all manufacturers had added Cold Air Intakes.
They used to be a good add on for carbed engines that drew air from engine bay, but not any longer.
For looks and sound they can be worth while, but not for power, and if done wrong you will lose power.

 

Yep. The aftermarket floods the interweb with ads that boost "up to 12 HP gains" with a CAI. This was most likely true for applications such as a carbed engine, where it sat on top of the engine, and drew in hot engine heat. Then a brain engineer came along and created cowl induction; the engine was able to draw cooler air from the windshield area into the air cleaner.

With the modern engines, they moved the air intake to the front grill area to draw cooler air into the intake. The engineers have this right on 99% of stock to mild upgraded engines. Leave it that way unless you plan some sort of induction system, such as a turbo, or supercharger. This means you'll also be upgrading the exhaust (more air in requires the spent exhaust to get out quicker), plus a tune to re-adjust the fuel/air mixture and timing. All three of these will compliment each other.

If it's that "roar" your after, then remove the "muffler" type system that most stock air boxes have. Some have a square box along side the tube that runs from the air cleaner box to the intake. Others, like the Rangers, use a cone thats located in the air filter box. There's a write-upand Youtube on this forum or one of the others that show this simple mod. Or, if its eye candy your after, then its hard to beat a CAI with a off color air tube, and a nice pink/red/blue air filter.

Me? I've left everything the way it is. My 3.0 equipped Ranger was not intentionally built to set speed records. With 216K on its odometer, I think the Ford engineers got itn all just right the way it is.

If I want some weekend excitement, I hop into my 2011 Mustang!