Diagnosis Help for misfire and rough running

Hey everyone it’s been a while since I’ve posted because the trucks been running so darn good.

Anyway yesterday drove to the pool with my kid the truck was running totally great. Came out after an hour on a dry warmish day in the low 40s. Started the truck and it was immediately obvious that it was running rough and had low power. The gas tank had gotten a little low and the fuel light was flickering which is usually no big deal but I decided I had better throw a fuel filter on it so I did. Which was admittedly a knee jerk reaction. By the time I got to test drive the truck it was cold again and ran surprisingly well for a half mile up the road and a half mile back. I had somewhat convinced myself problem solved.

I parked it for an hour and then went back out to take my kid to town for a class and it was running rough as soon as I started it. Not quite as entirely rough but it did throw the code again but it didn’t lock it in. I got the flashing engine light which then stopped flashing but it didn’t lock the check engine light on. When I got home I checked codes and had a pending P0305 code instead of a confirmed P0305 code.

Right now I’m heading out into the driveway to take the coil pack off the number five spark plug take a look at the plug and will probably throw a new OEM plug in it and swap coil packs with its neighbor cylinder three. I know that if it’s a coil pack I would probably be getting two misfire codes but I’m that far along I might as well just swap them for the heck of it. While I’m there I’m gonna try to check the ohms on the fuel injector for cylinder five.

That’s as far as I’ve gotten just wanted to give the description of events in case this jog someone’s memory or sounds familiar. Thanks!

 

Hey everyone it’s been a while since I’ve posted because the trucks been running so darn good.
Anyway yesterday drove to the pool with my kid the truck was running totally great. Came out after an hour on a dry warmish day in the low 40s. Started the truck and it was immediately obvious that it was running rough and had low power.
The gas tank had gotten a little low and the fuel light was flickering which is usually no big deal but I decided I had better throw a fuel filter on it so I did. Which was admittedly a knee jerk reaction. By the time I got to test drive the truck it was cold again and ran surprisingly well for a half mile up the road and a half mile back. I had somewhat convinced myself problem solved.
I parked it for an hour and then went back out to take my kid to town for a class and it was running rough as soon as I started it. Not quite as entirely rough but it did throw the code again but it didn’t lock it in. I got the flashing engine light which then stopped flashing but it didn’t lock the check engine light on.
When I got home I checked codes and had a pending P0305 code instead of a confirmed P0305 code. Right now I’m heading out into the driveway to take the coil pack off the number five spark plug take a look at the plug and will probably throw a new OEM plug in it and swap coil packs with its neighbor cylinder three. I know that if it’s a coil pack I would probably be getting two misfire codes but I’m that far along I might as well just swap them for the heck of it.
While I’m there I’m gonna try to check the ohms on the fuel injector for cylinder five.
That’s as far as I’ve gotten just wanted to give the description of events in case this jog someone’s memory or sounds familiar. Thanks!

 

I just posted your exact message but added a couple paragraph indent things, seems like I notice folks avoid the longer posts that look like it could be hard to understand. Yours was actually easy because you at least had it all punctuated lol
But it sounds like you're on the right track to me. Verifying what the misfire is from first and you're testing the things most likely to cause a misfire. Let us know what you find man

 

Well, I pulled the 1,3, and 5 spark plugs. Put in fresh mid grade NGK’s swapped the 3 and 5 coil packs for the heck of it.

Test drove it a mile to the gas station and filled it up and added some fuel system cleaner. It was warmed up for the ride home with normal idle. Seems totally fine now. Maybe it was just plugs. Going to do the other side tomorrow with the kid. So I got a bonus fuel filter out of the deal. It looked original so 218,500 miles later it probably was not a waste. Kid gets the truck when he’s 16 so he won’t have to do it. Hahaha!

 

Hopefully it was just a bad plug. If it happens again I'd then consider the injector.

 

It’s happening again and I’m considering the injector. Thank you!

 

Did the code follow to the cylinder where you moved the coil pack to?

 

Runs pretty good cold. But as it warms up it starts to run rough. Especially if I dive a few miles and then shut it off and it sits for 10 minutes then I restart it. The idle drops a bit from normal and than it’s really rough under load.

The error code which is marked “pending” instead of “confirmed” is still P0305 so it didn’t follow the coil.

 

After watching a lot of diagnostic videos and reading forum posts the pattern of events really feels like an intermittent fuel injector on #5. And likely caused by an actual failure of the electronics on the injector and not the ECU or wiring harness. I’m glad I did the fuel filter. I’m glad I did the plugs and swapped coils around.

Am I missing anything here? I hate talking myself into something by overlooking something or leaving something out of the equation.

I’m considering just replacing this one injector instead of trying to find reputable remanufactured ones and doing all six. I’m willing to if someone knows a good reman supplier. Pretty much looks like I’m taking the intake manifold off and all that Jazz. I’m going to get all the gaskets an o-Ring’s.

Any hot tips, video links, suppliers, special tool recommendations? It’s January in Maine so I’m going to borrow a neighbors garage and my almost 13 year old son is going to keep things organized and drive the iPad as well as turn some wrenches.

While we are at it we’re going to do the valve cover gaskets.

Thanks! I appreciate your thoughts so far!

 

With what I understand of what you're saying it sounds like you are spot on my man. That cylinder even got a new plug, so can rule that out, but also got a different coil wire. And coil pack right? We can eliminate that as well unless you already did and yessir that leads us to next most likely and that would be injector. Especially with the new stuff you posted about running rougher and being harder to start as it warmed. You've been very clear in communicating what you've done, what you're thoughts are, and what you plan on doing. Seriously. I commend you for this as it will help us, the forum folks, big time as a diagnostic or 'help figure out' type of thread.

 

I had something similar happen and started with changing the coil pack. I ended up having to change a fuel injector. I haven't had any problems in 5k miles after replacing. I had a similar sequence when the truck would run fine then run rough for a period of time.

 

Well since it’s cold I’m and finding a heated garage is not easy and I just need the truck up and running I’m tempted to just do the number five injector.

Based on a couple of videos it looks like after removing the throttlebody I could get to the passenger side fuel rail. This reduces the complexity of the job in terms of not having to take the entire air intake off. Worst case maybe I could just take the top of the air and take off. Then in the summer I can go in take it all off and do the valve cover gaskets and replace the rest of the injectors.

Anyone ever just do a passenger side only injector this way?

Here’s a good video that makes me think I can do just one rather easily. From 10:30:

https://youtu.be/N-lhZIWOkyU

 

Just throwing it out there but have considered checking the compression of the cylinder and comparing it to the adjacent ones?

 

Ya, I know I should do this. I should have done it yesterday. I can probably get a loaner test kit from a parts store. I’ll add it to the list for Monday which is when I plan to try to remove the passenger side fuel rail. Thanks man. I’m really hoping it’s not a compression issue!

 

So, I’ve got three new injectors coming and 6 banjo bolt gaskets (crush washers) of which I need 4 now and two when I do the other side when it warms up. Also have a throttle body gasket. Weather looks good for Monday and I found this thread!

https://www.tacomaworld.com/threads/replacing-injectors-what-else-while-i’m-there.522162/

 

Injectors are in. No banjo bolt gaskets in hand so I’m down til Monday. I did get a heated garage though!

I posted new questions here about crudded up ports in the injector holes. Am hoping it’s not a valve issue.

https://www.tacomaworld.com/threads/injectors-are-out-don’t-know-what-i’m-looking-at-photos.650513/

 

And she’s running great! I got up this morning and decided to reuse the banjo bolt gaskets. At the point where I had the fuel rail all torqued I pulled the coil pack connectors off and cranked the engine over for a bit to pressurize the fuel system. No leaks! The rest was easy. She runs damn good and I only did half the plugs and injectors. I’ll finish in the spring when it warms up. Thanks for all your input guys.

 

I'm having that issue. Here's my experience... when starting the truck with a cool engine, the truck runs great, with random exceptions (occasionally, and randomly, it has run a little rough upon initial start.) If I turn it off when it's running great, and turn it right back on, it runs fine still. However, if I turn it off and let it sit for about 20 minutes and turn it back on, it's running rough, the engine making the truck bounce up and down like something's out of balance, and throws an engine light. Code reads as misfire on #5. Swapped coil packs with #1, reset computer, and eventually get a new code which still reads #5. Replaced spark plug on #5, and the problem is still there. I have noticed twice that the engine started running slightly better after making a hard turn. I will be replacing the injector soon.

 

Hey man I missed this over the weekend! That's great to hear! Make another mark under the heading 'misfire caused by bad injector'! Thanks for keeping us updated on it too. Happy that took care of it hermano

 

Sounds very familiar. Sounds like #5 injector to me. Do the long screwdriver as stethoscope trick. I was able to confirm my injector wasn’t firing before tearing it out. Made the job more pleasant. Not that there could not have been other reasons for the injector not firing like maybe a wiring problem or a computer problem but those are highly unlikely.