Engine Misfire on Cly 1 only during Idle P0301 - 2007 Tundra 5.7

So I had a misfire happening on my new to me 2007 Tundra 5.7l. (ISSUE IS NOW FIXED)

Symptom 1 - I can feel engine misfire only during Idle (at least to me it looks like it) ever 10-60 sec sometime less...sometime more just depends. How do I know its misfiring? the engine idels very smooth and then when the engine misfires the engine shakes a little like its taking a burp and then goes back to smooth operation.

Symptom 2 - Got a P0301 - Misfire detected on Cylinder 1 - got 4lo, traction control, VSC OFF & check engine light ON. Erased the code - started the engine again and got it out of limp mode.

Troubleshooting Steps - May not be in the order I put below.

- Put this up on Techstream --> Engine & ETC --> Monitor --> Misfire --> Details ---- and found the following

EWMA Misfire 1 - 80 <- Shows history I think this one is tell us what happen over last 10 trips
Misfire Rate1 - 463 < - Shows what has happened since you pulled the Monitor codes. So this is happening right now on the car. (Figure 2)

Refer to this video for Techstream misfire

So did the following -

1- Swapped the Cly 1 Coil with Cly 3. Same misfire found on Cly 1 through TS. So it was not the coil.

2. Then took spark plug 1 and 3 out and found the spark plug to be in good shape. However the spark gap on 1 was very small. Like smaller than .02in. Which I thought was odd. The gap on spark 2 was better at .038in.

- I looked up what the official gap supposed to be for the 5.7. It is .044in or 1.1mm. (Figure 1)

3. I then thought...I wonder what would happen if I swap the spark plugs keeping the original gaps. i.e. Cly 3 to 1 and 1 to 3...When I did that and pulled up the TS monitor. The Misfire rate started happening on Cly 3. Whooohooo I think I found it. (Figure 3)

4. Adjusted both spark plugs to the .044in gap...put them back in and problem SOLVED... When I pulled up TS Monitor I no longer got any misfires.

So moral of my story check your spark plug gaps and ensure they are within specs. Not sure why the original owner didnt check the gap but it was what was causing my problems.


Figure 1 - Spark Plug Comparison between Cyl 1 & 3


Figure 2 - Initial Misfire showing on Cyl 1


Figure 3 - After swapping Spark Plug 1 and 3 - Clearly the Misfire follows the spark plug 1. (look at misfire rate3)

 

nice work, this will surely help someone in the future with a similar issue.

 

Damn. Always nice when it's something easy and cheap!

Wonder if the installer dropped that one and didnt even look before shoving it in.

Do you have a fancy gapping tool for these iridiums? I only have the old style which can damage the tiny electrode.

Luckily the plugs I got from the dealership were within spec, but I suppose I need to pick up an appropriate gapper as some point

 

@COTundie No bud I didnt even know there is a new gap tool to gap the Iridiums plugs. I used the old style kind. But I know the plug was Iridium and was extra careful in gapping and testing the gap. i.e. No harsh moves on the tip of the plug to crack or scrape it. I just used good judgement to gap it. Also btw to enlarge the tip using the old style gap tool the hole to enlarge it only touch the end of the spark gap (ground terminal) and the side of the spark gap. I did not have to touch the Iridium tip at all. So IMHO no need to buy a fancy gap tool, just be smart and you'll be good.

 

Well if I could consistently just be smart it would probably solve a lot of my problems.

But its the weekend, I drink beers to solve problems.

 

excellent work. its great to see spot on diagnostic work and following the steps to the solution.

 

The plug on the right had no gap at all. It had to start throwing codes the moment he fired the truck up. Just curious, why didn’t you check the gap on the misfiring plug before reinstalling it?