Took my truck (99 150 4.6) to my mechanic it was bogging at 60 mph or on inclines. It idles fine & I can get up to about 55-60 mph then if i give it gas it bogs & the check engine light came on.

They hook it up to the computer & it read a P0304 cylinder misfire. This could be 3 things 1- plugs & wires 2- ignition coil replacement 3- fuel injectors...

They put new plugs & wires in & it ran great for a week then started doing the same thing but worse. It still idles fine but when I give it gas I can feel something holding back at any mph & there are loud popping noises coming from under my hood. Im bringing it back to my mechanics later in the week...my question is should I put a fuel injector cleaner in it.. does this stuff really work?? I've always been hesitant in putting chemicals in my engine and is there anything I can check to see if it is a bad coil.

Also I wanted to know what octane gas people put in. I put in 87 regular from reputable stations like Bp, sunoco etc...should I put in a higher octane gas??

thanks

 

me of all people should know misfires!. how many miles are on it? what kind of plugs do you have? that loud poping noise is a back fire out the intake valve Fuel injector cleaner just makes your gas a higher octane. and burn hotter. i dont know if they work i just get them when there on sale 2 for 1. i had the same prob. it idled fine but the second i put it under a load itd missfire like crazy.

 

Last night I had the same misfire, constant, but noticeable when put under normal load.
no loud popping noise though (that I can tell)
I just bought a code reader and have a P0302... #2 CYL misfire

I had the same issue 2 months ago with my #1 CYL, P0301, and changing the coil resolved the issue...

note: Then, I was on a hunting trip and returning home with the overdrive off (to increase the engine rpm's) helped driveability.

I plan on picking up a coil tomorrow,
Unless I find a affordable COP set tonight.

INFO ON FUEL ISSUE:

4 years ago I had intermittant #1 and #6 misfire codes...
I ran fuel system/ injector cleaner, it cleared the issue for 3 weeks, same codes came back.
Changed the origional fuel filter, DUH! ... Fixed problem.
1 month later, I had a hard P0301 though. Changed COP #1 and all was well for 3 years.

BY THE WAY, run the same 87 octane. Octane boosts will help performance, but will not resolve issues.
Prolonged use of higher octane without your systems being adjusted to operate at that octane can cause advanced wear.
If you want, get a superchip (or such) and those are set for higher octane performance.

p.s. bought a Equus 3030 Code Reader for $59 at Walmart. Best cheap reader with code sequence and I/M monitor status

 

spark plugs and spark plug wires?

 

Replace the Coil Pack.

Just use recommended gas.

 

How does running a higher octance cause advanced wear?

 

if you were off roading you could have got water down in the spark plug chamber and it arcs to the spark and will cause a misfire. this has happend every time ive got mudding in my truck. i just pulled the wire and blew compresssed air in the chamer and in the wire boot and it workd fine.

 

ANFO,

higher octane fuel is able to withstand higher pressue before it detonates,
it also burns more consistantly (which could also be described as slower).

you are able to advance the timing with higher octane fuel...
spark starts earlier,
the pressure is able to increase higher and be used more efficiently.

if you use higher octane fuel, without advancing the timing,
the fuel may not fully ignite through the cylinders power stroke.

the residual fuel vapor will exit out the exhaust, (why we have catalytic converters)
but it will also keep the cylinder wetter since more is not fully burned.
This washes the cylinder wall and the oil has to fight to remain and lubricate.

 

Thanks for all the replies....
Shifty what did u do to resolve the misfire with your truck??
BTW I have 130000 miles on her......
Im pretty sure its the coil...Again Thanks everyone!

 

well with cly 1 i replaced the coil packs and chaged an injector then it jumped to cyl 3 so i replaced all my plugs and wires again. motor craft plugs and motor craft wires. so i replaced everything coil packs wires and plugs. runs fine. if you were offroading id pull the wire and see if theres water or mud down in the chamber and spray it out with compressed air.