Needing help with 3.0

[Sweeten34]

I have a 04 ranger edge 3.0 that's got a slight miss at idle but when put under under load the motor bogs an misses horribly an won't get over 30ish kinda worried it's got a valve recessed it's not trowing any codes I have replaced mass airflow, coil, plugs, wires, air filter, o2 sensors (4), only mods now are cold air intake true dual exhaust a friend thinks it's a timing issue I think it's the heads it's had the miss before but would go away an come back finally it came back with a vengeance lol any ideas?

 

[Andy D]

Do a compression test, it would reveal a burnt exhaust valve. It is a simple procedure. If it is a bad valve ,it should throw a code for a misfire.

 

[RonD]

Dirty Fuel filter won't cause a miss at idle but will certainly cause bogging at higher speeds.

Compression test would certainly be helpful.
All spark plugs removed, throttle propped open(put something on gas pedal)
Test one cylinder at a time, hit at least 4 compression strokes each time(you will hear them)
Check tip of compression gauge for fuel on each test and wipe it off, you are checking if an injector might be clogged a bit

You should be above 150psi(my '94 4.0l still tests at 165psi), but what you are really looking for is the average psi and the high and low cylinders, so write down cylinder number and pressure, compression test is a waste of time unless you write it down.

battery(speed of starter motor) and pressure gauge can change the numbers so the number itself isn't what you are after it is the difference in the numbers from cylinder to cylinder you want.

General low pressure across all cylinders(130psi) could mean timing chain tensioner is failing so cam is falling behind crank(or battery is low, lol), but a rattling would usually be heard.

Simple vacuum leak is very common and will cause miss, sometimes on the same cylinder(lower intake) and sometimes random(upper intake)

 

[Sweeten34]

Ok compression test shows cylinder 5 @180 the rest are in the ball park of 165 on 4 compression strokes ideas ?

 

[RonD]

Reads like carbon build up in #5, it's fuel injector could be leaking, or the intake valve guide's seal is allowing oil in, or it had a bad spark plug or wire allowing unburned fuel to build up inside the cylinder.
Spark plug tip might tell you??
165psi on the rest means valves and cam timing are OK.

This cylinder was most likely the miss you felt coming and going, but not because of the higher compression.
The higher compression is the result of the miss, it shows it has been building up a carbon layer for awhile, which makes the cylinder area smaller so it now has higher compression than the others.
I would run Seafoam in the gas tank, $8, for the next two fill ups, $16, to clean out the carbon build up.
Some run it in the intake at idle via a vacuum hose to do a quick clean, I don't, but that option is available.

The bogging is either timing advance issue or fuel mix issue.
Fuel mix issue could be fuel pressure related, testing fuel pressure at idle, 65psi, and then at sustained RPM of 2,000 might reveal a drop in pressure if fuel pump/filter can't keep up, although I would think this would cause the CEL to come on as the computer reached it's "rich limit" while trying to compensate for the lower pressure.


You mentioned a CAI, could this have effected your MAF sensor's detection of ALL the air entering the engine?
The MAF sensor is the beginning of the intake manifold, so from MAF to cylinder intake valves is a "vacuum", all engine air must pass thru the MAF or the system won't work as designed.

 

[Sweeten34]

I've changed the fuel filter I was told maybe my pump is going out an the coil an plug wire were burnt to cylinder 5 so I changed the coil plugs an wires so next on list would be fuel pump an sea foam then if that dosent work injectors? Would that be a liable way to go about it after. Yea it has a cai however I've had it on the truck since 07 an the miss didn't come until maybe 2 years ago after broke crankshaft an rebuild about 5 months later the miss an bogging came so I don't think the CAI has had a neg affect (the air intake tube is smaller than stock)

 

[RonD]

There are inexpensive OBD II interfaces that allow you to view live engine data while you are driving.
The Bluetooth versions plug into the OBD II port and you can then use a smartphone or laptop as the display, $30-$50, check compatibility and cost of "app" before getting one.
On some you pay more for Bluetooth adapter and app is free, on others Bluetooth part is less but app is $10-$20.

These can be used on any OBD II vehicle, so any new vehicle sold in North America after 1996.
So not just for your Ranger and 3.0l.

This type of device might tell you where to look for the problem.
Constant fuel trims at rich end may point to fuel pump pressure issue.
erratic MAF data or spark advance could point to wiring issue on MAF or erratic CPS data.

Just a thought

 

[Sweeten34]

I do have a reader not a Bluetooth but dose have live data but doesn't give info on fuel system but a code just popped that both banks are lean showed up after playing hell with throttle. thinking about it there wasn't really any fuel on the tip of the compression tester that would indicate the either the fuel pump isn't pushing enough or all 6 injectors are bad correct?

 

[RonD]

Well all 6 injectors being bad would be a long shot
I would suspect computer or CPS(cam position sensor) before the injectors.
#5 with carbon build up could mean that one injector is leaking

Low fuel pressure would be first thing to check.
Yes on cold engine compression tester should have been wet with fuel.