2001 Ford Expedition OBDii CodeL P0300 - Random/Multiple Cylinder Misfire

[CharlesUSMC]

2001 Ford Expedition XLT, 5.4L V8 330ci (says Triton on the side of the fender?)

So I just finally got my Expedition inspected and all was well. The next day on the ride back from work I noticed the car seemed to be driving a little rough. It felt as though there was hesitation accelerating between 1k and 2k. Then the Service Engine Soon light appeared.

OBD AutoScanner reported the error, P0300, Random/Multiple Cylinder misfire.

After some research I determined that it must be my spark plugs. I purchased the vehicle with 80k and now it has 130k. It had Autolite plugs in it, which i replaced with motorcraft. (all 8 plugs, it took a while). However I am still having the same issue. I put some fuel injection cleaner in it because the injectors looked a bit dirty on the drivers side. Still no change... hesitates, feels like airplane turbulence a little.

Also the hesitation and misfire is not continous. It comes and goes. The service engine soon light reset when i disconnected the battery and replaced the plugs. now it has also started flashing at me on the highway, stays on fora bit and then goes away after i get off the highway and drive residental areas.

All of the coil packs were disconnected, inspected, looked fine and put back together when i changed the plugs. So I am not so sure a coil pack is the issue.

Also the car sat for about a month while replacing a broken tail light. just before this happened.

I know it could be:
* Faulty spark plugs or wires
* Faulty coil (pack)
* Faulty oxygen sensor(s)
* Faulty fuel injector(s)
* Burned exhaust valve
* Faulty catalytic converter(s)
* Stuck/blocked EGR valve / passages
* Faulty camshaft position sensor
* Defective computer

But i wanted to know if anyone else has seen this issue and might know what it is. Also a way to diagnose this "not so descriptive" error code P0300 i would appreciate it. Thanks.

Charles
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[ghettoracer]

Actually that happened to me when I was 40 miles outta town today. I noticed it was kind of hesitating around 45 mph when I go to WOT. I barely touch the throttle and it drives normally but when I go uphill it feels like that turbulence you described and I had to turn on the OD just to make it up the hill on 10% throttle. Got my belt replaced 1,000 miles ago and it started squeaking like a **** before I shut it off. Not sure if that is related but Im guessing the coil pack on my truck went or have "aged" spark plugs because they haven't been changed since the truck was first bought in 1997. I have a 1997 EB with 169,800 miles on it so I'm throwing a guess that it is ignition related. Mine also flashed at me and then stayed steady. I'm guessing its the same code.

Did your suck gas when it started hesitating? Mine sucked up a lot of gas when it did.

 

[CharlesUSMC]

From what I have heard, the coil packs rarely go bad. I didn't see anything wrong with any of them, but I don't know how to test them. Yes my car has been eating through gas, but my subaru friends said that its common to get low gas mileage when you have a steady misfire of the cylinders. I sure hope someone around here knows, otherwise its off to the dealership for $100 diagnosis which I don't have right now.

 

[ghettoracer]

ok well I took my car to get scanned today and pulled up a p0306 and p1451 code. I believe the that EVAP canister solenoid is bad and its contributing to the #6 cylinder misfiring.

 

[CharlesUSMC]

p0306 code definitely means that Cylinder #6 is having a Misfire. I have replaced all 8 spark plugs, fixed bad negative battery terminal connection (corrosion) and today i am going to replace my fuel filter...

It seems to be running better since i have replaced the plugs and battery terminal... however it is still having multiple/random misfires while accelerating. I am curious if i just purchased a bad tank of gas. It didnt start happening until i filled up my tank when it was a few gallons spent after the LOW FUEL light.

Its down around 1/4 tank or less. Im going to add 1/2 tank of Premium from a different gas station and toss in the bottle of fuel injection cleaner after i replace the fuel filter. If this doesnt fix it, ill have to take it to get diagnosis.

 

[ELVATO]

You could try this?
http://autorepair.about.com/od/troubleshooting/ss/coiltest-manual.htm

Also, yea, change the fuel filter, since you may have picked up gunk from the bottom of your tank, and the filter could be partially blocked?

 

[CharlesUSMC]

I knew you could test a spark plug like that with carb. engines (rotor button, distributor cab, etc.) but i didnt know if it was okay/safe to do with fuel injection. I will give this a shot after i replace the fuel filter.

Wish i had tested them when i actually pulled all the spark plugs out... since they are a pain in the a$$ to get to. Thanks.

 

[ELVATO]

I'd guess just crank the engine, but try not to start it.

 

[ELVATO]

On the other hand, some other solutions I've read to testing...

-Drive at a speed/gear where you are missing the most (like drive with O/D off to force engine more) and see if it evenetually throws the code for the specific cylinder.

-This http://www.f150forum.com/f6/how-test-coil-pack-17249/#post140124

-Have a friend help you. One of you start the truck, press and hold the brake, and put the truck in gear (some people give the engine some gas while doing this). Other person goes in engine, and starts disconnecting connectors to COPs, one at a time. Disconnecting good ones will cause engine to stumble and shake. Disconnecting a bad one will cause no change (since a bad coil is almost like having no coil.)

-Just buy 8 new coils from here or here, and save yourself the hassle.

 

[ghettoracer]

Elevato, thats what I did turned the O/D on and it threw the code, it will blink at ya then stay steady.

I'd just take a flat head and stick it down the COP and see if it archs off some metal but make sure your handle is isolated with rubber or something cause I did that once without a handle and got the zap of my life.