07 Misfire on cylinder 8

Diagnostics show I have a misfire on cylinder 8. I replaced the spark plugs and everything was running perfect. Next morning check engine light is blinking along with VSC. I got to where I was going, went into the store, came back out and my truck ran perfect once again. This morning, same issue, check engine and VSC is blinking. What should my next move be?

 

Swap coils between cylinders and see if it follows the coil

 

What the burrito said. If the issue stays with the cylinder, instead of moving with the coil pack, then you know it’s not the coil pack, or vice-versa.

I do have to ask though, are you loosing any coolant? Any sweet coolant smell to the exhaust when it missfires?

 

14burrito Thanks, I already pulled the trigger on 8 new coil packs....
landphil, coolant is good and the exhaust does smell a little rich but not sweet.

 

That’s good news. A cylinder specific missfire usually only on cold start-up after sitting can be a sign of coolant slowly leaking into the cylinder from a head gasket failure etc. A coil pack or even 8 would be far easier on the wallet, and a very real possibility.

Do keep us updated.

 

I had the same issue with my 2012, it happened under hard acceleration. The truck went into limb mode, the vsc was flashing, check engine the whole nine. Turns out it was a it was a bad coil. Swapped out the bad one, changed sparks. All was good until a sold my truck. It happened at 50k sold truck with around 120k

 

NjPro, thank you for the input and helping me stay positive on this. She's been good to me for 8 years, 230k miles and I have only had to deal with the starter. I will update when I receive the coils on Wednesday.

 

No worries, we all know the feeling. For sure keep us posted. Good luck.

 

11 Days later.....
Replaced the spark plugs, ignition coils....same code, misfire on cylinder 8. Took it to a mechanic to see if they could diagnose further, they check compression on the cylinder...it was good $85. Same problem popped up 2 days later....told them I was low on gas when it happened, put gas in, started it up and no issue for the day. They thought it might be a hose to the fuel pump issue, hairline crack in the hose. Took it to another mechanic, today....they had it all day and have pin pointed it to the fuel injector or the computer. They left a device on my injector for me....if the issue pops up again, when lite the computer is sending the signal to the injector and it is the injector, if the light goes out, it is the computer.

Fingers crossed that it is the injector!

The mechanic had an emergency to handle and I will be seeing him on Monday...would not take any money from me until it is fixed.

I will update next week....hope this helps at least one person.

 

Could a fuel pump cause this?

 

15whtrd, No...I forgot to mention that part.
I took it to the 2nd mechanic because he was going to charge me half to do it....
Within an hour, he had ruled out the fuel pump issue.

 

Thanks for the update. Also it is really cool the mechanic is not trying to fleece you. Good luck.

 

NjPro....he is an awesome mechanic, as of right now.

It is sad though, just found him but his ranch is almost complete in Mexico and will be leaving soon.....Levy is his name.

 

[QUOTE="Damien311,

It is sad though, just found him but his ranch is almost complete in Mexico and will be leaving soon.....Levy is his name.[/QUOTE]


This sounds like the beginning of western book or movie.

 

NjPro....I'm thinking you are on to something.

 

Update....
Drove it this morning, half way to my destination and the check engine light came on. Got to where I was going and looked at the sensor the mechanic put in...light was off. Meaning it is the ECU not sending proper signal to the injector. No clue on cost, may look for a scrapped Tundra to pull it off of.

Will update on Monday.

 

I think a used ecu from a wreck will be the best way to go.

 

NjPro....We were thinking the same but, Ebay has them for around $250...I will see what advice of the mechanic has.

Being an electrician myself, I do not want to pretend to know the best route.

 

Agreed, I would be a lost sailer at sea trying to swap out the ecu.

 

Update....
2nd day that I have had it back and it seems as though the problem is fixed.
He determined it was the ECM, ordered it, installed, and programmed.....a bad injector shows up.
He states that the bad injector caused the original ECU to fail.

Again, I am an electrician trying to follow along and understand.....
I want to believe him but I am about 80%/20%.

Here is the bill I was sent: (keep in mind, he spent 4 days trying to pin point the issue)
1) ECM - $220.00
2) Re Programming $140.00
3) Injector $155.00
4) Oil Change $75.00
5) Labor $300.00

Seems Pretty Legit to me.....Comments?

 

Seems legit, glad your up and running. Peace of mind will come the more that time passes with out any lights on the dash.

 

What do they have to program onto the new ECM? I also don’t understand how a bad injector can ruin an ECM.

 

NjPro...You are very correct, I had a dream this morning that the check engine light came on....I hope this will pass.

15whtrd...I can not answer that, I just hope he is being honest. Truck is running great, who am I to question?

 

You need to tie the VIN to the ECM through the "cloud".

IMO he only charged you for the injector because he couldn't return a used part. Thats unfortunately part of the "part swap" diagnosing game.

 

That's a rare case for the ECM to go bad resulting in a misfire. I'm a mechanic and when we get a misfiring car 90% of the time it's a bad coil, 7% of the time it's a bad spark plug, 2.999% of the time it's the injector. Rarely, actually i've never seen one at my shop with a bad ECM causing a misfire. Glad you are up and running, the bill that you're charged with is not bad at all.

 

I agree with FXFormat's numbers, but in my case, I have seen ECM's going bad due to a failed injector. Most common injector failure is excessive resistance, caused by undergoing multiple heat/cold cycles. But once in a while you see an injector with little or no resistance, most commonly known as grounded or shorted, this would typically blow a fuse, but in some instances the path to ground isn't strong enough to blow a fuse, but too consistent for the ECM to keep up and ends up burning the Diode the controls the circuit for that specific injector. Now on the other hand, when that's the case, usually Technician will find the failed injector first, since is easy to test injectors and figure which one is "shorted". After replacing it, and if still having a missfire you'll know the ECM has also been affected and needs to be replaced (or fixed if you know what you're doing), so with that being said, if the tech tested injectors while hot and cold and found no issues, chances are a grounded wire on that injector circuit was the culprit and could have fried the computer, and if not addressed properly, it will eventually ruin the new one too.