Misfiring engine?

Hello,

This sounds like this could be a vacuum leak. A vacuum leak is called in the industry as letting unmetered air into the engine. This is defined as any air entering the intake tract after the Mass Air Flow(MAF) sensor and before the combustion chamber is unmetered air. This means air that the Power-train Control Module(PCM) has not accounted for and therefore is making your engine run lean. This will cause idle and driveability concerns. I have included a few links for you to go to down below.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge
https://www.2carpros.com/articles/engine-misfires-or-runs-rough
https://www.2carpros.com/articles/engine-vibration-at-idle

I have also included a factory basic troubleshooting chart for you in the diagrams down below. Please go through these guides and the chart and get back to us with what you find out.

Thanks,
Alex
2CarPros

Engine Performance problem
1997 Ford Ranger 6 cyl Four Wheel Drive Automatic alot miles
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i have had a problem with this vehicle for a while and i'm hoping i can finally resolve the problem .. it started as a misfire so i figure since i had over 200000 miles it was time now { just a note i bought with this many miles anyway }to tune her up so i did and nothing changed the scanner kept telling me #2and #4 misfire so i said to myself its probably the coil pack , nope its not that then a friend suggests fuel injectors i had to have two of them replaced and still skips the engine has only about 55000 miles on it and it was a rebuilt so i thought compression nope not that either it has 150lbs across the board then i was told it could be a fuel pressure regulator { guess what } nope !! so i did a fuel pressure check and it has at start up around twenty pounds and at idle it has about 35 ish can this be my problem ? o by the way i also replaced the intake gasket because two people had suggested at one time this is what they encountered . so i say HELP !!!!

your knock sensor could be shot, thus retarding the timing(causing the misfire). check it out and get back to me, also check the plug wires, or did u do that already

one more thing, I would also check the throttle position sensor just for good measure, if none of these are the problem, you may need a new computer

My Ranger every time that I crank it goes through a really rough spell, After I crank it seems to run ok for a minute. after that it runs so bad that you would think it jumped time. I can turn the key off and on without letting it die and it clears up for a minute and then starts back missing. If I keep it running by patting the gas in about 30 seconds it clears up and runs great until the next time i recrank and it starts all over again. I have no clue . Please help.
Thanks,
Neil M

Start with spark plugs.
Replace them and inspect the old ones to see if they have any cracks or missing parts on them. Continue with replacing them. If same problem re-occurs, it could be that either the piston or piston wall may be cracked, and may need a new engine.

After completing a valve job I have noticed a pause or blip while idiling. This can also be seen if one puts a timing llight on any sparkplug wire and watch the light. This seems like a spasmatic missfire. Has anyone a idea of cause?

If it didn't do this before, it must be the result of the work. Are the crank and cam sensors in good condition? Also, has the check engine light come on?

Let me know.

Joe

No check engine light, cam sensor wasn't disturbed during previous repair, crank sensor seems good gap has been varried with no change.
Seems to me that if one of the sensors was bad the miss would happen within each revolution of the engine. Also if it were the coil that cylinder would have a continous miss. This miss happens once every few seconds which would be several revolutions of the engine. It also doesn't seem to be at any time other than idle.

The only thing I can think of is a bad or damaged wire. Since it isn't consistant and only at an idle, I wonder if there is a wire that is broken or nearly broken.

Bought this truck used about 2 years ago. Changed plugs and plug wires do to an engine miss and all was good . Year later miss came back, engine code " mis fire no 4 cylinder". Changed plug, miss corrected. Year later same thing. Had to replace only No 4 plug to correct engine miss.
Any idea what could be causing this. Plug looks good when i pull it. doesn't look fouled.

IT could be caused by a weak coil or injector.

I have a 2.3 5 speed ranger. My engine light came on, it said cylinder 1 misfire. I checked my spark plugs, got a spark, checked my wires, got a spark. Checked the coils, number 4 worked fine, but number 1 did not. However, on an ohm check, both coils got a good readout. If a coil gets a good readout, but is not firing, what could the problem be?

Check and test the crankshaft position sensor.

would the crank position sensor effect just one coil, even though 1 and 4 are supposed to fire together?

You need to check it the CPS tells the computer the position of the pistons and engine speed then in turn fire the coil/s. Also check the ICM come back with some results.

My Truck is a 1996 2.3 I4 Ford Ranger. The problem I am currently having is that the truck misses and feels like it is bogging out after about 3rpms. It started by doing it occasionally but recently started doing it whenever I drive. It is almost impossible to go over 50mph sometimes. I replaced the fuel pump about 8 months ago and it ran perfect since. As soon as it started acting up I changed the plugs, coils, wires, fuel filter, air filter, cleaned the MAF and throttle body. I cannot figure out what it is for the life of me. Could it be an erg valve stuck? Stopped up cat?

The EGR will not do that at that RPM, I'll do an exhaust backpressure check to rule out the Cat.

Could be the TPS not hitting on its sweet spot-check the closed/WOT voltages. might want to check the MAP/MAF sensor too.

Also won't hurt to recheck the fuel pressure. could be the regulator not maintaining the pressure.

I have 96 ford ranger v6 4.0. for about a year I have had a head gasket out. i have tried several liquid fixes with no success. about a month ago my truck became gutless and started to misfire. shortly after my cousin and I just finished up the head job. the truck was sitting for a while i have tried driving it, and it shakes and misfires just like before and is shooting fuel out of the tail pipe. i have checked all the hoses, the spark wires are only about a year old, and everything appears to be fine. could the bad head gasket and the fact that i put those additives in my radiator have caused my Thermal Valve Vaccum/EGRvalve, PVC, or O2 sensors to go out(I replaced my O2 sensors 6 months ago)?

Engine running rich can be caused by the following:

1.Excessive fuel pressure can be cause by restricted fuel return line
2.Defective Oxygen Sensors.
3.Leaking injectors and fuel pressure regulator.
4.Coolant temperature sensor out of calibration.
5.Restricted air intake system.

trying to get master cylinder off how do you take wires off rod for clutch m cylinder also the rod off the peddle its a 1996 ranger

remove the pin holding the brake light switch on the master rod. the switch will come off when the pin and bushing is removed.

Roy

I have a 96 ranger 4cyl. 5-speed. Engine light comes on. Scanner says P302. No. 2 cylinder misfire. Seeing that I have 2 ignition coils for 4 cylinders, if one of the coils were going bad would it not read 2 separate cylinders misfiring ? If that was the case I should only check spark plug and gap or spark plug wire as the problem ?????
Thanks
Bill from ohio

You can buy seperate plug wires at soem auto parts stores might be a good place to start

Please Help I have a 95 ford ranger 3.0 and it is missing at idle and when cold but after driving for about 15 min. the missing cylinder kicks in and the truck runs fine what could be wrong ? The miss does come back at idle at all times.

Sounds to me like you need new plugs and wires. Also I would change fuel filter. All together at autozone-under $50.00. Easy fix

Put new plugs and wires on truck less than a year ago autozone will not check codes only 96 and newer will try replacing fuel filter and get back.

Engine Mechanical problem
1995 Ford Ranger 6 cyl Four Wheel Drive Manual

my truck is sounding as if it miss firing when i look under the hood the engine is not hot and the anti freeze is missing

If the coolant is missing, we need to determine where it has gone. Is there any evidence of a leak? Have you checked the motor oil to make sure it isn't getting into the engine? Also, has the check engine light come on? Have you refilled the coolant? If so, how long does it take for it to get low again? Finally, is the exhaust from the truck white or light gray in color?

Let me know.

Joe

After replacing head after severe overheating, head was cracked in three cylinders, the engines misfires.
Checked compression, low but even. Cam, crank, and oil pump in index.
Retrieved codes of PO 300 Random Misfires,PO 340 Camshaft Position Sensor Circuit, PO 351,352 Ign Coils A & B.
Cam and crank sensors have resistence of .346 K ohms or thereabouts.
Cam circuit has one wire that goes to ground. The crank cirduit does not. I assume that both sensors work the same.
I do not know how to check out PCM.
I never saw the truck run normally before replacing the head.
I don't have ready access to scanner.
Any help directing me in right direction will be appreciated.
Barry.
Any help will be appreciated.

Ok how did the spark plugs look? Have you checked the spark plug wires? If not ohm them. What was the compression?

I replaced the spark plug wires. One plug had insulator blown out. All the others had gaps of over 100/1000,yes almost 1/8 inch. I had never seen that before. The colors varied from black to gray, all were clean.
Compressions were 105,100,100,95.

Ok so are we talking about the plug wires or the spark plugs themselves? As for the compression not good. What I would like you to do is redo the test one dry and one wet. Now this must be done with the engine warm ok. Now first check compression as normal write down the findings, then do a second compression test with a squirt of oil in the cylinder (through the spark plug hole) write down the findings here too. Get both readings back to me. With compression that low and that spread out you will have a miss that can not be fixed. Just for your info minimum compression is 130 per cylinder, I think we are going to find that the engine is just tired.

Spark plug GAP, not a mistake, of over .100 in. Can't get motor hot as I have coolant out in order to check crank and cam sensors
Compression this time is 100,110,110,100. All cylinders went up 15-20lbs. when I squirted Brake Clean in cyls. I uses brake clean to as to NOT foul the other spark plug on each cylinder. Compression tester may be reading low because it is hard to tell if it seals enough to get real reading. As I said, the engine runs,albeit with a random miss.
Would really like info about how to tell if PCM, crank, cam, sensors and circuits are working properly. This controls the two coil packs.
Thanks.

Is this compression test done cold or hot? If it is done hot then the engine is just tired as the compression is below 130 which is minimum compression to run correctly. With the compression bumping up that much when wet just confirms the engine is tired. The reason for the random missfire is because of the drop in compression. I can give you test procedures if you like but it will not change much with the low compression. Cam shaft sensor- first check power to it- first disconnect it and then (using the diagram below) check for power at the VPWR term should be 10.5 or better with key on engine off. If it is then computer is doing its job and sensor is getting power. Now check resistance between pwr gnd and ground should be 5 ohms or less. Let me know what you find.

Compression done cold.
The diagram didn't come through.
What is VPWR?
No power at cam sensor plug, neither terminal.
What do you mean by pwr gnd?
I need to assure customer that bottm end rebuild will solve problem.
Thanks.

Sorry I must have forgot to include it. Here is the diagram. Again the customer needs to understand that less then 130 psi per cylinder indicates the engine is needing either replaced with a remanufatured engine (better choise) or rebuilding the one in it. Here is your diagram.

The cam sensor is a 2 prong. This Ranger is a 95 with OBD 2.
One prong has no voltage and the other goes to ground in the PCM.

Ok OBD2 started in 96 not 95 with a two prong cam sensor then you do not have a hallofect type that all. So if you would give me the production date it may be a late model. Also on an OBD2 system the camshaft sensor is used to determine camshaft position and when cyl 1 comes to tdc for start up. Now using the diagram below for the 96 model year check the restance on term 91 and term 85 between camshaft sensor and pcm connector should be less then 5 ohms. Now if resistance checks out ok then check sensor output. To do this truck must be able to start and run. Set you volt meter on AC voltage and check while running voltage between pin 85 on the sensor and term 51 and term 103 at the pcm. If voltage vary's more the .1 volt then replace pcm if voltage don't change more then .1 volt then change the sensor. Also I must ask why did you drain the antifreeze to check the crank and cam sensors? From what I can tell you only need to drain coolant to remove the crankshaft sensor and it can't be tested that way as it needs to be pluged in for some of the tests. Let me know what you find. Camshaft sensor

PCM

WHEN I TAKE OFF FROM A LIGHT AND PRESS THE ACCEL PEDAL SLIGHTLY, ALL IS WELL. IF I DEPRESS THE PEDAL TO FAR THE ENGINE STARTS MISSING AND JERKING VIOLENTLY AND SOUNDS LIKE ITS BACK FIRING THRU THE EXHAUST.