Cylinder 4 misfire, most common causes (1 Viewer)

[Nightbrew]

Hey guys, after a 45 minute one way drive pulling the boat to the lake and back, my rig started idling odd and then ran horribly for a few before throwing the cel. Stopped by O'reilly's on the way home and scanner said cylinder 4 misfire. Rig is running rough especially at idle and acceleration. My instincts say it is either a plug or wire. Previous owner has new plugs, wires, cap etc about 23,xxx ago. I know parts can be bad but I wanted to see what are some of the more common causes of this code.

 

[george_tlc]

Could be a dead injector.

Here's my #6 failure writeup to give you some ideas for debugging:

Injector Service

cheers,
george.

 

[chap79]

I've had a spark plug fail before. And I've also had a distributor cap break and have a floating connection point.

 

[baldilocks]

Per the FSM, which I'm sure you own a copy of, oil in the spark plug tube is the first thing to check for when a misfire is problematic. The FSM is your friend.

 

[inkpot]

Start diagnosis cheap and easy. Pull #4 plug wire and see if it sparks when grounded. Make sure #4 spark plug is tight in head. Pull that spark plug for visual inspection/ replacement if spark test is good. Check injector harness clip if tight. Inspect wiring harness around EGR for heat damage. May need to open wiring bundle to check individual wires. Run compression check on that cylinder. Check oil and coolant for signs of HG failure.

 

[Nightbrew]

I didnt even think about an injector. I will check my #4 plug and wire and go from there. I sure hope its not a head gasket

 

[Nightbrew]

Guys thanks again for the help. I do indeed have a bad plug wire. It was jumping out of crack near the boot while testing. Any advice on wires? Whats good and what to stay away from. I dont see a brand on these anywhere

 

[Nightbrew]

Also while removing the breather hose to get to the #4 plug I found this disconnected ground wire. I will post a pic of both ends, can someone tell me where the "free" end is supposed to go?

 

[inkpot]

Free end goes on the firewall under the bolt that holds the support bracket for the wiring harness.

 

[Nightbrew]

Free end goes on the firewall under the bolt that holds the support bracket for the wiring harness.

I will check that out, thanks

 

[Nightbrew]

Any opinions on plugs and wires, I will probably purchase later today. Thanks again

 

[BILT4ME]

Toyota for both.

 

[Mighty690]

^ Ignition: keep the system 100% OEM.

P.S. I know I, but an oil analysis is probably a really smart thing to do now. Towing, followed by misfire, .... I don't even want to say the words.