DTC P0305 - cylinder #5 misfire

This problem started last week, so I changed plugs and wires over the weekend. Took the car for a drive last night and the problem seemed to be gone. Drove the car 1/2 hour to work today, including 70 MPH on the highway, and had no issues. Pulled off the highway and engine began to stumble. Had my code reader with me, and pulled P0305 (cylinder #5 misfire).

I will check the coil packs for primary and secondary resistance tonight, and switch them around to see if the misfire follows the coil pack for #5. I will also check and clean all battery connections. If I find nothing by that point, I will pick up some carb cleaner and look for vacuum leaks.

I searched the forums for similar problems, and see the following can also be sources of this problem:

ICM - I know what this is and where it is. Other than checking connections, is there any way to test the ICM? What is the cost of a new one?

Bad injector - should I switch #5 injector with one of the others? Are injectors easy to remove and install? Am I asking for trouble if I do this without new O rings?

PCM - what and where is a PCM? What does it do? Can I test it? What are the chances it can cause this problem?

Do you have any other suggestions?

Roy

Try moving the injectors. It'* a messy job. The gas is under pressure to push in the shradder valve, have a towel over to soak up the gas. Remove the 4 bolts holding the fuel rail down and lift. It will take some effort. The O rings should be fine. Unplug the wires before removing the fuel rail.

The PCM is under your air box. It controls everything. I don't believe that'* your problem.

Thanks Dan. Are you leaning toward the #5 injector as the problem? I was planning to change my fuel sending switch this weekend, and someone posted a proceedure for releasing pressure in the fuel system. I will follow that procedure before pulling injectors. How much crappage (technical term) do I have to remove to get at the fuel rail? Is there one fuel rail, or two?

Roy

Id still switch the coil packs first,,,, cleaner and easier ,,,,, might get lucky

Agreed, test the coil first.

There should be nothing much in the way of the fuel rails. It sits on top. There is only one rail

Absolutely. Coil packs are first. I just like to forearm myself with ideas about what steps to take next so I can move forward after the coil packs, instead of having to wash my hands to get back on the computer to see what to do next.

Dan or Obnoxus, what are the chances this is in the ICM? Is there any way to check the ICM other than switching it out for a new one?

Roy

im going to go with minimal,,,,,,,, coil pack,,, injector,,,,, bad wire/connection is where I would put 90% of my money

ICM has a big goose egg chance. We only have three coils. Each coil fires both towers at the same time. So if #2 isn't complaining, then the ICM is firing the #2/#5 coil as it should. I have seen more coils lose one tower than I have injectors bad...but that'* simply luck of the draw on what I've witnessed.

If teh coil test good, and the injector is not the problem try a compression test.

Thanks for all the input. I have a game plan on what to do, and in what order. I will post updates and questions as I proceed.

1. check coils (resistance testing on primary and secondary sides as per procedure Dan posted some time ago).

2. switch coils, to see if problem follows the coil pack. If the problem follows the coils, replace the bad one. Probably replace all 3, but I will ask your advice if we get to that point.

3. if problem not in coils, switch injectors and see if problem moves with injector #5. If it does, replace bad injector.

4. if problem not in coils or injectors, do a compression test on cylinder #5 (I think I actually have a compression gage at home).