PO302 number five cylinder misfire

[roscoepm]

Hi,
I also have number five cylinder misfire. Change the ignition coil and spark plugs.
Here is how I got to this situation. Mine only happens at high RPMs as I was passing Somebody the engine light came on engine ran rough.
Engine light, then went off truck ran fine. I did a test and floored it again. Engine light came on and stayed on, went home and found the code PO 302 number five cylinder misfire. I changed the ignition coil did the test same roughness high rpm but light never stayed on. Cleared the code did it again high rpm light came on ran rough light went off. Change the spark plugs same thing. Getting ready to swap out fuel injectors to see if that’s the problem. Any ideas?

 

[TorqueWagon]

I had similar symptoms on my 6.7 Cummins. In my case it turned out to be a bad injector wire on cylinder number 5 which caused the misfire. I verified it by removing the valve cover gasket and using an ohm meter to check every single one of the fuel injector wires. Sure enough one of the wires for cylinder 5 was open. All of these wires pass through the oil gasket (valve cover gasket). I went down to my local auto part store and got a new valve cover gasket with all of the injector wires and swapped it out and it's been good for many many miles since then. Simple solution, relatively cheap. It was about 100 and a half Roughly. I don't know if the 5.7 is done the same way but check your fuel injector wires first. Use the KISS rule! Hopefully you'll get off cheap. Good luck.

 

[Wild one]

Hi,
I also have number five cylinder misfire. Change the ignition coil and spark plugs.
Here is how I got to this situation. Mine only happens at high RPMs as I was passing Somebody the engine light came on engine ran rough.
Engine light, then went off truck ran fine. I did a test and floored it again. Engine light came on and stayed on, went home and found the code PO 302 number five cylinder misfire. I changed the ignition coil did the test same roughness high rpm but light never stayed on. Cleared the code did it again high rpm light came on ran rough light went off. Change the spark plugs same thing. Getting ready to swap out fuel injectors to see if that’s the problem. Any ideas?

Time to do a compression test,and it probably wouldn't hurt to pull the drivers side valve cover and have somebody bump the engine over as you watch the rocker arm movement.If one rocker isn't moving as much as the others,park it ,till you can have the cam and lifters replaced.Keep driving it,and you'll fill the engine with metal filings,and then you'll have even more head aches

 

[roscoepm]

Thanks for the advice

 

[jawzs2]

Isn't P0302 a #2 cylinder misfire code, P0305 would be #5?

 

[roscoepm]

Your correct my bad. It even says #5

 

[Burla]

The usual suspect is lifters, how many miles on engine? They usually start to fail with load, meaning high rpm in drive or towing. If it is worn cam it will only get worse. Never throws a code when cold at start up?

 

[roscoepm]

The usual suspect is lifters, how many miles on engine? They usually start to fail with load, meaning high rpm in drive or towing. If it is worn cam it will only get worse. Never throws a code when cold at start up?

It has about 154000 miles. Yes at high rpm's only. Only throws the code then and it goes away.. Thanks

 

[Wild one]

It has about 154000 miles. Yes at high rpm's only. Only throws the code then and it goes away.. Thanks

I'd jerk the valve covers off and check rocker arm movement if it was my truck.

 

[roscoepm]

I'd jerk the valve covers off and check rocker arm movement if it was my truck.

Thanks I will