2017 5.7L V8 Tundra

hey yall, i just wondering if anyone knows what i should do here I have been getting a P302 code on my code reader for the last week or two now. I know it’s a misfire code so i did spark plugs, ignition coil, fuel injector, cylinder connector and a MAF sensor the other day. From what my code reader is telling me is it’s only happening when the truck starts i’m only having between 3-25 misfires it on when the truck starts. After that it’s fine it does not shake or have a rough idle still has good power and everything like that. I checked my oil for milky oil and have found nothing. I just don’t quite get what’s going on at this point after changing pretty much everything i can think of. I took it to autozone just for the hell of it to see if there “code reader” could find anything else on it and it popped up a c1201 but i’m figuring that just due to the initial misfire when the truck starts. If yall have any adivce before it gets taken to the dealer ship please let me know. Thank you

 

Have you monitored your coolant levels during the time this problem has been occurring? I know you said the oil wasn't milky but a small head gasket leak (or cracked head) that just allows coolant into that #2 cylinder when the engine cools off overnight, could explain your issues. A borescope in cylinder #2 after the engine has sat overnight can rule in/rule out any internal coolant leaks.

That being said, did you use OEM parts for the injector, coil pack, and plug? Did you test the resistance of the old coil pack you removed?

 

I have been having a small coolant leak but it’s loosing pretty much nothing it takes about 2 or 3 months for the leak to actually drain a full reservoir of fluid. I have not done anything deep into the engine yet but at this point that’s the be dry thing i’m going to do is a broescope in to see. All of the parts used were OEM besides the connector which was one i just bought from autozone. I tested the ignition coil but having someone start it while i had my finger in the end and it still had a good spark (it shocked me pretty good). What had been making me think it’s not a head gasket leak or somthing like that is that it will misfire on start up even when it’s warm and at operating temperature. Pretty much anytime the truck is shut off and turned back on it having the start up misfire.

 

Valley plate leak?? I have coolant disappearing too. Onlyndifference I'm getting a sweet smell in my AC, so maybe its a hose leaking somewhere.

 

So to be clear you're filling your coolant reservoir every 2-3 months? And do you have any visible external coolant leaks? If not, then an internal coolant leak becomes a very likely cause of this misfire issue.

 

Nope the only thing that i think it could have been leaking from is i’ve noticed a small amount dripping on the front sub frame but have not been able to pin point where it’s coming from. When i tasted it last time it didn’t seem to taste like coolant so i may give that another look aswell.

 

And i have not even looked at the valley plate so that may be where i start tomorrow morning.

 

What plugs did you install? And whence did you purchase them? What did the old cylinder 2 plug look like? Any chewed/frayed wiring under the hood lately?

 

Plug was a Denso OEM plug from what i could tell online. Thats what was in the truck before. I just for the hell of it looked at the fuses in there and they were pretty much all either burnt or had blueing on them so i’m not sure if somthing not shorting itself out and it’s leading to the fuses. No frayed wires or anything like that under the hood though.

 

plugs were also bought same day as install and i work at autozone so i would go and li k the best ones out of the boxes.

 

You need to pin point which cylinder is causing the misfire or if there is another issue causing it.. Assume a more in depth code reader is needed..

 

I have it’s the number 2 cylinder only on start up from what live data is telling me. After start the misfire goes away.

 

One way to start eliminating possibilities - swap the spark plug with 4 and the coil with 6. See if your misfire moves.

 

You can also try a block test, to see if exhaust gases are getting into your coolant.
As other members have mentioned it could be a slight leak in your head gasket.

 

i did swap ignition coil and spark still stayed at cylinder 2

 

don’t hate on tasting fluids now i can tell you motor oil and coolant taste alone different

 

This would lead me to believe your head gasket could have a very small leak, like others have said when your engine cools a small amount works it's way into your #2 cylinder causing the misfire, then when burned off it's gone.
I know it sucks to hear, but you can try the block test to be sure, if there is a leak the compression of the cylinder will force gases into the coolant and you can see it with that test.
Best of luck to you

 

I actually have a miss on my 2014 scion TC only in the morning and it misses one time and then it’s good. I am going to go do a block test right now on that car.

 

Borescope showing a steam cleaned cylinder would confirm HG leak.

 

And this is another surefire way to determine is well.

Just did my Scion TC and thankfully no gases in the coolant.

Also, checked my 17 Tundra for good measure, all good there as well thank God

 

Those combustion gas testers for the coolant system are semi-notorious for having false negatives (missing a cracked head or failing head gasket).

Borescope is a much better method of confirming, especially when combined with a coolant system pressure test (pressurizing the coolant system on a cold motor will push coolant through a failed head gasket or cracked head and into the affected cylinders).

 

Borescope is a preferred method I agree, however if you properly perform the block test you get good results.
Makes sure vehicle is warm and thermostat is open.
Test directly on the radiator neck.

Again, Yes you are right sir, a steam cleaned piston is a dead giveaway.