random engine misfire code?

2001 FORD RANGER
155,000 MILES • 6 CYL • 2WD • AUTOMATIC
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BILL BIEBER
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The temp gage failed motor locked down; tryed to restart motor not kowning that and battery shorted. I had the motor replaced with remanf. with new wires, plugs, ignition coil, and CKP. Service engine light came on when I got the truck home about 10mi. The shop looked a the codes and said that it said random misfire. They reset timing drove truck no light. U/P truck get home light returns and it did seem like it was missing on long slight grade. I returned to shop they checked the truck and said that the camshaft position rod needed to be replaced; that was done and now when you are in drive and it shifts from first to second gear about 3000RPMs it seem like it is reacting as though you were in park revving the engine and the RPM limitor is trying to restrain the engine and the light has returned. They want to replace the PCM now. What do I need to do to stop the misfiring and clear the code.
Jan 8, 2010 at 6:22 PM
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RASMATAZ
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P0300 normally points to vacuum leak and bad fuel

This guide can help us fix it

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

Engine misfiring could be caused by worn or fouled spark plugs, a weak spark (weak coil, bad spark plug wire), loss of compression, vacuum leaks, anything that causes an unusually lean fuel mixture (lean misfire), an EGR valve that is stuck open, dirty fuel injectors, low fuel pressure, or even bad fuel.
Jan 8, 2010 at 6:33 PM
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RANGER78
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When Im driving on the highway doing about 60 or so my truck starts shaking then my check engine light comes on and starts flashing if I slow down to under 60mph it goes off. The other day it stayed on solid so I took it to have the diagnostic error code read what up is PO302 misfire at cylinder 2. What could be causing this the truck seems fine when Im not driving faster than 60?
Jul 29, 2020 at 11:04 AM (Merged)
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RASMATAZ
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Engine misfiring can be caused by worn or fouled spark plugs, a weak spark (weak coil, bad spark plug wire), loss of compression, vacuum leaks, anything that causes an unusually lean fuel mixture (lean misfire), an EGR valve that is stuck open, dirty fuel injectors, low fuel pressure, or even bad fuel.

P0302 Cylinder misfire at No.2-you should check the sparkplug, compression and injector for this cyl.
Jul 29, 2020 at 11:04 AM (Merged)
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RANGER78
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well spark plugs wires coil egr valve are all less than 5 months old
Jul 29, 2020 at 11:04 AM (Merged)
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RANGER78
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What do you think is the most likely cause since it only occures when Im driving faster than 60mph?
Jul 29, 2020 at 11:04 AM (Merged)
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RASMATAZ
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There's other things involved here such as the following

Oxygen sensor
Dirty fuel injectors (cleaning the injectors often fixes this).
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)

Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include:

Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires
Jul 29, 2020 at 11:04 AM (Merged)
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SHARRIS9US
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when driving between 40-50 mph my truck will buck,skip something and cannot figure what causes
Jul 29, 2020 at 11:04 AM (Merged)
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RASMATAZ
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Check and test the following below:

Oxygen Sensor
Catalytic Converter
Dirty fuel injectors (cleaning the injectors often fixes this).
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)


Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include:

Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires
Coil and Rotor
Jul 29, 2020 at 11:04 AM (Merged)
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LEGACYHI
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Just did a tune up on my rig about 4 months ago. changed spark plugs, wires, and fuel filter. I have the oem air filter box still in the truck, but i replaced the filter with a k&n about a year ago. anyways, i have done tune ups before on this truck and everything has always been fine. since this last one however, i keep getting the check engine light coming on when it's idling. brought it to napa, they checked the code, and it keeps coming back as "cyl 5 misfire". so i replaced that plug with a new one. still doing it. my gas mileage is terrible. usually i can get 240-260 miles per tank. now i get about 180 if i'm doing good. any ideas what might be the problem?
Jul 29, 2020 at 11:04 AM (Merged)
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BLACKOP555
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do you have a separate coil for that cylinder?

have you changed the spark plug wire as well? you can test it it should have no more then 10,000 ohms of resistance per foot of wire.

if thats all good and your getting good spark on that cylinder you should check the injector. listen to it with a stethoscope and compare its sounds to other injectors. sound the same or different?
Jul 29, 2020 at 11:04 AM (Merged)
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AIRFRAMER1973
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I got a misfire on cyl #1 (code PO301). I'm getting a blue spark on the spark plug. So that tells me the plug, plug wire and coil pack are good. I changed the plug about 3 mths ago when I first got the code, and it looks like it's never been used. It's not brown or black or anything. It's completely dry also. So, now I'm thinking fuel problem, right? I got 12.8 ohms on the injector itself, which is the same as the #2 injector. Ok, so that tells me the electrical side of the injector is good. I decided to clear the code. It did run a little better but I can tell the engine is still mising. The code has not popped again yet, but the check gauge light did blink a few times with a full tank of gas. All other gauges were normal. What's my next step? Can someone send me in the right direction?
Jul 29, 2020 at 11:05 AM (Merged)
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BLACKOP555
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try swapping the injector with another. if the problem moves with it you should replace the injector set. because they run under the same conditions. same fuel. one goes out so will otheres
Jul 29, 2020 at 11:05 AM (Merged)
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DDP
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Problem with a misfire on #4 (according to computer). Isolated to fuel injector problem and have been told that I need to do all 6 and not just 1. Can only one injector be pulled, checked and replaced/repaired or must all be done? This is a 2000 Ford Ranger.
Jul 29, 2020 at 11:05 AM (Merged)
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KIN CHAN
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is okay to do one, but is more likely the rest are about the same condition as the defected one. scope and volume test can verify the condition of the rest.
Jul 29, 2020 at 11:05 AM (Merged)
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KASEKENNY
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You can replace one injector at a time. That school of thought comes from people who only want to take apart the vehicle one time. So if there is something wrong with one just replace them all while you are there because they suspect the others are going to fail as well. However, I do not subscribe to this because if it is not broken I leave it alone. These injectors deliver the same fuel so unless the fuel is contaminated which caused the failure, I would only replace what is broken.

Here is the process for replacing the injectors.

Please reach out if there are issues. Thanks
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Jul 29, 2020 at 11:05 AM (Merged)
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MAXOOM
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shows misfire on cylinder 6. new spark plugs and wires..what else could it be?
Jul 29, 2020 at 11:05 AM (Merged)
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MASTERTECHTIM
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Hello,

Lets start by checking the compression and the color of the spark plug which tells us if the injector is working. Here is a guide to help us get started.

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

Please run down this guide and report back.
Jul 29, 2020 at 11:05 AM (Merged)
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FLETCHONE
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I had a slight skip when driving. I replaced plugs and the skip was still there. I replaced wires and the skip is worse and misses on idle. ?? Help !!
Jul 29, 2020 at 11:06 AM (Merged)
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RASMATAZ
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Engine running rough or misfiring can be caused by the following:

Defective spark plug
Inadequate spark/coil,defective spark plug wire.
False air leakage.
Faulty fuel injectors.
Insufficient fuel pressure.
Contaminated fuel.
EGR valve that is leaking.
Oxygen sensors.
Throttle position sensor.
Idle air control valve.
Jul 29, 2020 at 11:06 AM (Merged)
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BRUEN1957
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2000 ford ranger has a very temporary mis in it when first starting but not as long as it did before I replaced plugs and wires. when missing I can smell a little fuel for a second making me think its not an injector but ignition so I'm leaning towards a coil pack. runs great all other times with 213000 on her. any advice?
Jul 29, 2020 at 11:06 AM (Merged)
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DWCROSSETT
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Running really rough, engine light... code says missing on cylinder 4. New plugs and wires... works for about 5 miles starts to run rough again with engine light.

Going to run a compression check tonight... possibly look at injectors and switch 1 and 4 to see what happens.

Anything else I'm missing. Missing cylinder error is pretty vague.
Jul 29, 2020 at 11:06 AM (Merged)
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BLACKOP555
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sounds like you got it well figured out.

have you checked for spark on that cylinder?
Jul 29, 2020 at 11:06 AM (Merged)
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JSTOKER06
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i pulled the truck up to the gate and all of a sudden it started misfiring. took it to autozone to have it tested and he said that cylinder 6 was mis firing. replaced spark plugs and still have the same problem. i do not believe that it is the coil or the wires and we tested to make sure that all the cylinders had fire and they do.
any help would be much appericiated. also on the highway only misses at low rpm.
Jul 29, 2020 at 11:06 AM (Merged)
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JACOBANDNICKOLAS
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If you replaced the plug, the wire is good, the coil is good, and you are getting a hot spark at the correct time, there is one of two problems. First could be low compression in that cylender, which is hard to believe because of the low mileage. Or, you could have a plugged or damaged injector. Have you checked to see if the injector is getting a pulse?
Jul 29, 2020 at 11:06 AM (Merged)
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AL514
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Here's a good one for ya guys. So I can't get this truck to set a code, at all. It has a misfire due to what looks like a vacuum leak, but (here's the weird part) we unplugged the MAF, unplugged an injector, plus the constant miss and this thing won't set any codes. Yes I have communication, live data stream. MIL comes on at KOEO. I haven't checked the ECM powers and grounds yet, but I wanted to see if anyone has seen this before. I'm not a ford guy. But I need to find out what smoked this ECM before I call it. Possibly a shorted sensor. I haven't check the 5v ref yet either. Thanks guys
Oct 10, 2020 at 10:23 AM (Merged)
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STRAILER
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Hey Al,

What burns up ECM's are shorted fuel injector or ignition coils. I would test each before plugging in a rebuilt/new ECM. Check power and grounds as well. Also unplug the 02 sensors I have seen the heater short to ground. Let us know.
Oct 10, 2020 at 10:23 AM (Merged)
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AL514
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Hey Ken. I actually don't think it's a bad ECM. It seems from a little research that fords have a lot of criteria that needs to be met for a mil. I've found misfire data for the #3 cylinder. But no hard faults. There's a pid #53 that counts misfires. But it's hard to find. So Im assuming the #3 isn't a dead miss yet. But I can feel it in the truck. But I will check all those you've listed for shorts to ground first.
Oct 10, 2020 at 10:23 AM (Merged)
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STRAILER
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It could be the injector shorting let me know,
Oct 10, 2020 at 10:23 AM (Merged)