misfire in cylider 4

[josephga]

A issue almost 10 months old. my 2000 4.0 ranger started misfiring with a cylinder 4 code. so far I've done the following. new plugs, new wires, new coil pack, changed gas filter, cleaned fuel injectors. checked and passed compression test What's left? lol
Sometimes it will go away for 2 months them come back. I'm guessing fuel injector replacement or a problem with the computer box is all that's left

 

[Brownie Mobile]

Im not too familiar with the 4.0 is it distributorless? if so check your distributor i cracked my dist. cap at one of the terminals and that created a double misfire on top of the one i already have all the time, so i had a v4 for a while. Also another cure is a 5.0L swap.

 

[RonD]

Well you can swap injectors around and see if problem follows injector or stays with #4.

What does the spark plug look like after misfiring starts up?
Is it clean like washed with coolant?
Maybe a valve seal is letting in oil now and again as crankcase pressure changes, is plug oily, make sure PCV valve is clean and working.


My '94 4.0 got a cracked head between valve seats on #4, it started out as a mystery misfiring, but there was a loss of coolant over time, with none on the ground, never a good sign .
Compression test didn't show it at first, bouncing glove test did, but missing was almost all the time by then and coolant loss with white exhaust smoke as well.

Are you noticing coolant disappearing?

 

[josephga]

coolant was disappearing but it was found too be a cracked heater valve. they replaced it.
it was still leaking and was checked yesterday and one of the hoses had to be trimmed and tightened

 

[adsm08]

An issue in the crank tone ring could cause this, but it wouldn't be intermittent.

Did you flush out the fuel rail when you did the injectors?

 

[josephga]

I had all the work professionally done. first time i had all the plugs changed and wires. then plug 4 turned black the next 2 times and was changed. yesterday plug 4 looked fine but still misfired. there was a coolant leak at the heater valve related too the hose that was fixed and still it misfires at cylinder 4. back in September it just stopped then started back again 2 weeks ago