000 4x4 with the 4.7L misfire codes P0300-301-302-304-308-308P

[motornut1965]

I have a 104,000 miles on my 2000 4x4 with the 4.7L and on the way home the engine started to run ragged and misfiring and the check engine light started to flash.

Here are the codes I pulled P0300-301-302-304-308-308P. Today I changed the plugs using OEM, new fuel and air filters, FI Cleaner, 15 gallons new gas. Ran for 20 minutes and no engine light but had a skip. I Shut down , waited 2 hours and when I started the engine again, the light flashes again and I get the same codes. What else can I do, loss of power, can barley take off but when I put in N and race engine it will go to 4500 OK but at low speeds it skips and putters. I really am appreciative for any help, I am 65 years old with stage 4 cancer and need my truck. Any ideas or help?

 

[Duane]

plugs, leads and ignition are easier culprits perhaps.
I just had a go round with my 3.4L V6.. P0300 and 0302 and 0305 codes..would flash as some say indicated 150%+ emissions so don't keep driving or could damage converter.

Mine ended up being a worn key and crank pulley causing the timing to wander all over.
Maybe a loose crank sensor can cause the problem??
Try finding a garage that subscribes to Identifix to see if they have these codes coming up and have a fix or several fixes on record.
Good luck
I attached a pdf of some ideas on what to check. Although it is for a 3.4L V6 I think it would apply to a 4.7 as well.

 

[Gumby]

I don't have the codes handy, but P0300 is random misfire and the rest are cylinder specific, right?


It's interesting that the misfires are in order. 2,1,8 and 4 all fire in a row. Other than 1 they are all on one bank. IIRC 2,4, and 8 are on wires with the odd side directly on the plugs. Might be worth checking the wires. Doesn't seem likely that it would start all at once though, unless it started to rain.

If you have a hard miss that you can feel, try a cylinder balance test by pulling each injector plug off one at a time. The one that causes no change in the miss is a dead miss and that would be a place to start.

Did any of the plugs indicate a problem? White electrodes might indicate a vacuum leak. Black electrodes might indicate too much fuel. Could be a MAF.

At that point I would start checking things with a scan tool, a noid light, and my coil and injection testers, none of which you are likely to have.

If you could get misfire counts with a scan tool that might be helpful.

I'm sorry I can't just point to one thing, but it could be a lot of things and I'm not going to direct you to start throwing parts at it.

 

[Gumby]

Alldata does not have any TSBs on that particular problem.

The code flow charts all suggest MAF in addition to vac leaks, injector problems, ignition problems and a ECT. It seems strange that you would have 4 injectors or wires go bad all at once, but a harness problem could cause that. CKP or CKP could cause it too, but not likely. I'm less likely to blame a CKP since you can feel a miss.

Misfire is a two trip logic unless it can cause cat damage, so it makes sense that the light didn't come right back on.

I'm liking a MAF, but I'm not going to say you should go out and spend the money on one without complete diagnoses. If you know someone who has a 4.7 you can swap a MAF with, or you can try to clean yours.

 

[HiFiGuy]

OP,
Any word on the problem? Mine started showing 300, 304, 307 and 308 plus (I think) 02 sensor and one more that I didn't get to write down. It started by saying six codes.

I need help with mine cheap, too, so any insight would be much appreciated.

 

[97 FZJ80]

Timing belt slip could also cause the misfire codes on one bank of the engine. When was the last time the timin belt was changed?