whats wrong with my engine it misfires?

This guide will help us

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

Hi Guys. I'm having slight trouble with my '94 3.0V6 Ranger, approx 60K miles. When the engine is cold, then truck runs fine but once the engine warms up, the truck misfires constantly. I've done serveral part replacements; new plugs, leads, cap and rotor, even the coil. My mechanic thinks it could be the distributor itself. Any ideas? By the way, this only started to happen when i replaced the plugs and wires. I checked and rechecked the wires and plugs. When my mechanic checked the wires and plugs he mentioned the misfire wasn't from any specific plug, more sporadic.
Thanks again, Phil

Random misfires that jump around from one cylinder to another have an underlying cause that is often a lean fuel condition, which may be due to a vacuum leak in the intake manifold or unmetered air getting past the airflow sensor, or an EGR valve that is stuck open.
Did you try putting back the old plugs and wires?

Good hunting and let us know. :)

Thanks for the info. I replaced the EGR valve, I'll have a play with the truck this weekend.

Well, here's the answer to the fix. However, before I tell you, there's a leason to be learned. Never listen to your friends that say they're "car savvy"...always go with your gut instinct...My gut instinct kept telling me that the new spark plugs I had just put in were faulty...My mate kept telling me there's no chance that would happen...Well, the ceramic was cracked on one of the spark plugs which made the car buck like a bull when it was warm. ALWAYS CHECK YOUR PLUGS...EVEN IF THEY'RE NEW!! Thanks for all the help.

Thanxs for the update. Good advice. I have heard of that more than once. Not very common but a real PITA. :D

thanks for the reply

94 Ford Ranger 2.3 stnd 2wd, runs fine when it first starts, gets down the road and begins to***** and backfire. If I start out slow and down shift before its time to, it will go, but if I give it too much gas at first it hesitates,****** and backfires. It feels like its going to beat me to death. It loses power as I climb up a hill, if down shilt and floor it it starts to clear out the***** and backfire checked all fuel cdomponents, they rare ok. I was told it was an ignition problem. I charged spark plugs, dual coils, ignition position moduel. I even changed the 02sensor before the cat, cleaned the EGR, has good vaccum and I'm stumped. Do you have any suggestions of what I might check next. I'm stuck! Vicki

Could be caused by one of the following below

Oxygen sensor.
Catalytic converter.
Fuel injectors dirty/sticking.
Mass airflow sensor/Airflow meter.
Throttle position sensor.
Crankshaft position sensor
Knock sensor
Manifold absolute pressure sensor.
EGR Valve
Fuel pressure regulator leaking or defective fuel pump.
Fuel contamination.
Foul/defective spark plugs.
Open spark plug wires.
Ignition coil/Coil packs defective.
Incorrect ignition timing.
Cap and rotor.

Note:If it doesn't apply disregard it and keep testing

I replaced my alternator in Jan. When I unplugged and drove it unplugged it ran like nothing was wrong with it. Plug it back in and it****** and backfires like crazy. Still trying to figure out whats wrong??????????????

I can't get the old throwout bearing off of the slave cylinder. I tried the methods in the book: Twisting it to put pressure against the spring, then pushing down on the spring to release it. Nothing works. I don't want to break the slave cylinder because I want to reuse it. How do I get the throwout bearing off?

I just replaced mine. I figured it out from your comments, thanks for giving me a clue.
I removed the slave cylinder so I could get a good look at it. I turned the bearing counter clockwise until it stopped. Then I pulled and twisted CCW sharply. It popped off.
I know this is late for you but maybe it will help the next guy.
Cheers

After a long dedicated 14 years, thhr ranger is beginning to act up. Have replaced fuel pump, fuel filter, spark plugs wires etc. but the engine seems to be missing firing on a cylinder when idling. When under power, it seems that the truck is going to buckle over and shudders very badly. the fuel pressure is good @45psi.The transmission has about 160000 on it. It was running ok till I decided to do some PM on it and has never been like before. Every mechanic has pointed in every different direction. the truck passed emissions with flying colors two weeks ago when the problem was intermittent. Now it is continuous. compression in cylinder 3 is 75psi(as per the repair shop). What should I do next and what is the problem?
Thanks for your help......

260,000 miles is phenominal.

it may be time for a engine overhaul, sounds like the rings are wearing, how did a wet compression test handle? the pressure go up significantly?

75 is pretty low and will definetely make a missfire very noticble at low speeds.

Will be doing a wet test in a couple of days, but everybody wants me to swap the engine out, which I am very hesitant to do....Want to rebuild the head and the valves if that sounds like it will solve the problem. If the pressure comes up with the wet test then only I will swap the engine.......(indicating bad rings)... we will know pretty soon.

rebuilding the heads as you suggest could work if the rings arent worn.

might be time to checking the bearings also. the rings could be worn, the cylinders are probably worn.

Thanks blackop555 :-))
We will know better tomorrow after the wet test. i think that will decide if I need to swap the engine of work the valves and the heads. I really do appreciate your input. Let us wait and seee...........

My Ranger is not firing on cylinders 1 and 4 on the rear coil pack and has a rough idle w/check engine light. Pulled the code as multiple misfire. I replaced the coil but it had no affect. I verified no spark on 1 and 4 by simply using a timing light and checking all 8 plug wires on both packs. Yes 8, as it has 2 plugs per cylinder. I also pulled the plug wires off the coil with no arc on said cylinders. I want to know where I should be looking to solve this issue....ECU,,,sensor? Thank you.

no problem, i hope the best cheapest way for you!

if you need further assistance im here to help!

Check the crankshaft position sensor if okay -its coming from the ECU

Hello blackop555:
This time did the compression test myself and found that all cyls had roughly 170psi after 5 piston strokes.....
too high but seems to me that the mechanic could be wrong.........now does that point to a clogged convertor? two independent mechanics have already told me that there is metal coming out of the tail pipe.....truck drove smooth after I assembled the plugs back in the cylinder
really confused now???...,,,,,

Thank you. I will check the crank position sensor and report my findings.

hmm 170psi is a bit high, maybe a camshaft issue wouldnt worry as long as its runnign good now, could be that a spark plug wire was loose on the plug or damaged and when you were moving them around it made the wire complete connection again.

would like you to check on that one cylinder momentarly see if when the engine runs rough if the compression drops back down.

I replaced the CPS...That was a fun job. Ford made it darn near impossible to get out. Bummer it did not clear up the problem. So I guess on to the ECU. Can the ECU also be called ICM (Ignition Control Module)? And if so, what is the location of this part in the truck for replacement? Thank you.

I realy appreciate you hanging in there for me and geting me through this, blackop555.........
It is back to where we started. i will run over the truck to a muffler place to make sure the converter is not clogged. There are two holes on the side and I can feel the exhaust coming out of there. It has not run bad on idle and city driving like before, but definitely feels as if it is missing.....the same vibrations on park and idle and same when the transmission is engaged with brakes on............the worst part is tat it is not displaying any codes....says everything is good......

I found the problem. It was not the ECU/EEC.

thats what im here for.

chances all that would show up is a missfire code. but since pre obd2 didnt have missfire detection. it wont show up.

What was the problem? other people are interested on how you diagnose it and found the defective component/s

interesting observation........the truck has been running fine today(when it is a lot cooler here in Atlanta), but yesterday when it was hot, it acted up after running a few miles and being turned off in a parking lot .......hmm.....what can it be?
There was no sign of a skip and the acceleration seemed normal........idle rpm was higher.......is it a bad fuel pump out of the box? not being able to keep the prime? ......or is it the ecm not geting fed back properly rom one of the sensors (the brake light does not come on when I engage the parking brake).......btw, in summer time in georgia, the ethanol content can go upto as high as 10%..
so here you go blackop555, does any of it make sense?
Thanks again

uhh, check to see if the coolant temp sensor and intake air sensor are same temperature.

mainly heat would be affecting the igniiton system not the fuel system such as the fuel pump.

check the fuel pressure.

Hello Blackop555:
Did not act up yesterday, but checked the fuel pressure and was fine. Everyday when coming to work, it acts after it has been on the highway for about15-20 miles... every time.....The muffler people won't even do a diagnosis but want to change it out, citing it the miles on the truck as an excuse.......
Don't know......Do you know a good mechanic in atlanta who can confidently tell me what is going on? at this time everyone want to take a shot on the dartboard and want o change everything out on the truck.......

no i wouldnt, what i would look for would be a individual ASE certified mechanic. basically call around, describe it. see what they think and see if you an get a quote on it.

lots of corporations like to go and do big things to make more money.

Thanks blackop555 for your help. finally took it to a ford dealer and the truck did not act up when they had it for two days. they are suspecting a fuel injector. So I am going to keep driving it till it acts up. I have a stethoscope with me in the truck so in case it does, will try to figure out which one.

if your close enough you can take it to the dealership without turning it off and have them go for a spin!

hello its me again......
Had it going fine for 10 days or so, and then it acted up again....this time when i unplugged the ignition wire from the coil for #3 there was no change in th erpm, when i plugged it back, the engine was back to normal. the injectors were all working with a nice even clicking.
Do I need to change the coil pack? do we need to reprogram he ECM? what would you do?

if the coil is bad it could cause the injectors to act up and the spark.

i would try a cheap one that works and see if it remedies, its worth a try.

second you unconnected and reatached it ran good/ you remove engine running or off?

Thanks blackop555 for your reply..
The engine was running. when I removed the ignition wire, I could see the sparks from the coil to the wire boot, which in turn tells me that the coil was ok????
The wire sets in use are non-ford parts (the spark plugs are oem motorcraft from the dealer). I have already changed two sets of wires with the same result. Do you think that I should just buy the wire set from the ford dealer also???? Also go ahead, spend the money and buy a new coil from ford? Or is it something else that needs to be explored.....

This is so confusing........

measure the resistance of the plug wires, should be no more then 10,000 ohms per foot of the wire.

the coil, i would go with a cheap coil and if it clears up then chances are that was the problem, some aftermarket work just as good as oem.

Hello:
The wire set in use had an average resistance of about 6K/ft. replaced them with the other set that was about 2K/ft. So let us see the difference. Tomorrow if it is not better than will go out and buy oem plug wires and then the coil. guess all three need to like each other.....ha..ha..ha..

2k per foot, very very good! it dont matter if its oem plug wires or not no difference.

unless you want to.