Opinions Needed-Misfire

[Oldie1375]

Begin with some back-ground:: I bought this truck acouple months ago from a good friend that re-tired it to under a tree out back.It was sitting for about 1 1/2 yrs..I put a complete new front end under it,, 4X4 and redid all the brakes..After getting it on the road,I have a very pronounced mis-fire at mid to full throttle.Idle is smooth.

It does not do this all the time,,some days it is smooth through out all throttle span. It has 213,000 on it.. I have new (Motorcraft) Double Platium plugs and wires ready to go in it..Wires have never been changed!!! I did put a new fuel filter in right away.

Are there any other parts I should just put in right away?? He says that the coil is original also!! This has been a Really good running truck for Many yrs..I am confident I can make it so again.

I have read many threads on misfire here:: Any suggestions would be Great,Thanks Much!!!

Added info:: This truck had NO misfire prior to sitting for 1 1/2 yrs.

 

[RonD]

Welcome to TRS

2001 Ranger would have the 4.0l SOHC engine, different from the 4.0l OHV used from 1990-2000

So misfire under load only

Run a can of Seafoam, or similar injector cleaner, in the gas tank, I am sure after sitting that long the fuel system will have a varnish coating inside it, could have fuel injectors that have limited flow, so Lean out mix under load

Next thought would be bad spark plug, since they are new, it happens, cracked electrode from factory or cracked while installing

Did it miss before the new spark plugs?

During a misfire the CEL(check engine light) should flash and then come on steady after that.
A code is set
P030X
X will be the number of the cylinder that was misfiring, 1-6, i.e. P0305 would be misfire #5
P0316 = random misfire, which would indicate a system wide issue, maybe lower fuel pressure

Ford uses a Waste Spark system
In the coil pack there are only 3 coils
This means 1 coil will spark two spark plugs at the same time, so 1 spark is "wasted"

Coil pack has a firing order
[3 4]
[2 6]
[1 5]
front

This means 1 and 5 spark at the same time, as do 2 and 6 and 3 and 4
The 5 6 4 side often gets mixed up so watch that when changing the wires

Coils do fail, and if one coil in the pack has failed then it may only show up under load, under load fuel mix is richer and recovery time shorter so stronger quicker spark is needed to ignite a cylinder.
You can test coil packs with an OHM meter, but problem with that is a coil can test OK cold with no load and act up when hot and under load, so..............worth while testing because bad coil will test bad but grain of salt on OK test


As a "heads up" the 1997 to 2003/4 4.0l SOHC engines did have a design flaw in the timing chain tensioners, this caused the chains to loosen up and break the guides.
It makes a rattling noise when this is happening
Newer design for the parts corrected the issue, so once parts are replaced the problem goes away
This wouldn't cause a misfire unless a chain had slipped, but that would cause overall lack of performance from lower compression on 1 bank of the engine

 

[Oldie1375]

Thanks Much for your info,,,I have read many Great responses from you,,,

I don't have all the new parts in it yet (Plugs ,wires,coil) hope to soon!!!

I did put some seafoam in it,,,but have only drove it about 30 miles since I got it,i will get the parts I have put in and hopefully will be able to get some good milage runs on it,to clean it out.

Side note: I received a buick car that didn't get used much,and had to put 4 fuel filters on it in the first month,,,reason I say this ,is because the prior owner (of the truck) drained all the gas out,and I know I stirred up all kinds of stuff off the bottom when I filled it up.I think I will put another fuel filter on,since my friend has a hoist!!!

I did know about the waste spark deal,,(due to Your info i found last week) I am putting the double platinum Motorcraft plugs in it!!!

Also,,,the feeling I get from the motor is kind of like a jerking feeling and to me it seems to not have good power,,based on the amount of power I feel out of my v6 in the car...could just be alittle tired (213,000 miles) LOL

I really understood what you meant about the plugs,from that link you shared,of the guy that took those really great pics of his plugs!!!!!

The motor is Not throwing any codes up at this time,,,it did have a code for small EVAP leak,,,but found that issue and it is corrected.

 

[RonD]

The "jerking or bucking" may be a dirty MAF sensor, worth cleaning it regardless because of the sitting so long