P0302

There are a couple hundred P0302 code threads on here but I haven’t found my specific issue. If you know of one please post a link.

Anyway, here’s the problem. The truck (‘02 DC TRD 4x4, 3.4L AT, 253k) has felt down in power a bit and smelled of gas in the exhaust for a few months. Figured I’d wait until it warmed a bit and stopped snowing before I tore into it. That idea went out the window last Thursday. Wife drove the truck to work (ice/snow) and came home complaining that the CEL has blinked and it wasn’t running right. Definite miss, scanned and found P0302 as the only code.

I pulled the #2 plug and it was black with carbon. (Plug on the left is #2 & on the right is #4). I swapped the PCV valve, grommet, & hose and cleaned up the plug. Still set P0302 so I swapped the #2 & #4 plugs, cleared the codes and fired it up. P0302 appeared again shortly after (within 3-5 minutes of idling). It seems to start out running fine and then it goes away. I think it’s getting fuel and spark based on the carbon on the plug and that it runs fine for a few minutes.

I’m assuming my next step will be to check resistance on the injector but I thought they normally fail closed, not open. For what it’s worth, the truck uses about a half quart of oil every 2,000 miles.

Anything I may be missing here? Thanks in advance for the help!

 

Try swapping the coils just to see!!

 

I’ll give it a shot. I guess I assumed if it was the cool I’d have two cylinders misfiring. I’ll check resistance on the plug wire while I’m at it. Thanks!

 

You could have no spark on one side and a intermittent spark on the other side or leaky injector I had coils do some crazy things in the past!!!

 

Okay, eliminated coil pack and plug wire from the equation. Any other ideas before I pull the upper intake to check the injector?

 

Time to check the injector!

 

@spinglow Thanks for the help. Checked the injector. #2 is at 14.8 ohms, exactly the same as #4 next to it. Any suggestions from here?

 

https://m.youtube.com/watch?v=j1c39taPXL4

 

Pulling the upper plenum isn’t too bad. I had to do it this afternoon to check my #2 injector. Be sure you pick up some upper plenum gaskets (2 identical gaskets) before you pull everything apart.

Mine is within 3-5 minutes of start up whether hot or cold like clockwork. I’ll do a compression test tomorrow (with any luck) and see if that tells me anything.

TW has been invaluable.

 

A valuable lesson was re-learned this evening. Always swap plug wires to test a misfire. I checked for spark at the misfiring cylinder (even swapped coils and checked the plug). Wasn’t until after I’d done a compression test and found cylinders all within a 15psi range (all but two dead even) that I swapped plug wires and the misfire moved. ‍♂️

Changed out the plug wire set and guess what?! No more misfire. It still seems to be running rich so I’ll clean the MAF sensor soon but at least the truck is back in service.

Thanks again for the help!!

 

I was having issues of lagging, sputtering and misfires, especially up mountain passes in all gears. My CEL never came on but I popped in the code reader anyway and P0302 came up. After researching and reading through this thread the first and cheapest thing I tried (spark plugs changed a few months ago) was replacing the three cables and boots running to the 2,4,6 plugs. It worked just fine and she's running tip-top again. The original ones lasted 216k miles so I'm not mad about it. I'm thankful it wasn't an injector cuz that looks time consuming. I threw a can of Sea Foam in the tank for good measure.

 

Changing out the spark plug wire set worked for me too.

 

You got that right. You probably saved me several hours of work.