08 Tundra with unfound cause after 5 mechanics

Hello, I have an 08 tundra double cab with the 5.7 engine with 145k miles. The dash shows several trouble lights. 4Lo, tpms, engine light, 4x4, and vsr I believe. Has new plugs, new fuel pump, new #3 injector, new battery, air cleaner, and a few sensors. If you clear the codes, the truck runs excellent and 4 lo works. Eventually, within 20 miles, the lights come back and the rear cylinders apparently misfire. It was throwing multiple misfire codes. The current shop mechanic scanned it live while driving and saw that the rear cylinders were misfiring. They can’t determine what would cause that. I know there’s a lot of other pertinent information of what they’ve tried, that would be helpful. I know one shop checked for vacuum leaks, but found none. The current mechanics checked the injectors. They aren’t perfect, but I didn’t want to replace them unless it was the cure. They don’t feel like it would fix my issue. I’ll try to find out anything you may need to know. Any help would certainly be appreciated!

 

Do you have a list of codes??
TPMS batteries may be dead and you will need to replace them or deal with the horror of manually checking the tire pressure yourself every morning or once a week, or whatevs.

If the rear cylinders are misfiring swap those coils to other cylinders and see if they change.

Edit: spelling

 

Swap injectors to see if the codes follow to the new location.

 

I have 2007 with 5.7, this happened to me. I am not saying that this is your issue, but it was a bad shift solenoid. I had about 175k when it happened at 192K now.

 

I would half agree with you. Shifting issues is probably a solenoid, but it wouldn't cause a misfire in the engine. IMO the easiest and cheapest way to test misfires is to test coils first by swapping them to other cylinders, clear codes and retest. Then go down the line by process of elimination. Check wiring for any type of damage, if the misfires remain in the same cylinders, then check spark plugs, if they're questionable cheapest way is to swap them with different cylinders and clear codes and retest. If the codes remain in the same cylinders, then test compression, at this point, odds are it's a gasket issue. Not jumping to conclusions just process of elimination to get to the root cause of the issue. At any point I would second what @Mdl stated and swap the injectors, if you feel comfortable.

 

+1

most common cause of misfires are coils. Certainly not the only cause, but is the most common. Kind of sad that mechanic didn’t think to check them. Shift solenoids will not cause misfires

 

I appreciate everyones' input. I picked the truck up late yesterday and trailered it home. I asked if they'd swapped coil packs around. He said they did initially, but when he was driving and monitoring it with his scanner, the rear 4 cylinders shut off. At that point, they figured it was due to another cause. They couldn't figure out what would cause the rear four cylinders to do that. At one time, they thought they had it fixed by bypassing a vacuum solenoid on the back of the manifold I believe. The truck ran fantastic and they put a decent amount of miles on it. They came in the next day to cold start it and pull it out of the shop and it was hard to start and ran terrible with all of the trouble lights on again. Back to the drawing board. I've heard people have had wiring issues that cause problems. What could cause such a problem, but be temporarily fixed with clearing the codes? When it runs good, it starts right up and can run down the highway at 70 with no issue, shifting like new. I'll scan for current codes later and let you know what they are. Thank you.

 

I scanned the codes. P0300 multiple cylinder misfire, P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308. I cleared the codes. The engine light came right back on when I started the truck and showed these codes again.

 

Check the grounding straps for the engine , along with the wiring going to your coil packs, it's an electrical signal not getting through, Maybe it's you engine control module gone haywire.
Eight cylinders misfiring all at once is a bit of a stretch, just trying to noodle , but this is wakky,, There are relays that control the ignition system. Identify which relay that us , see if there are
any others that have the same part number, say from the air conditioner relay for instance, swap the relays out and see if that makes it go away, again just trying help with a noodle or two.

 

SBGibson, those all sound like good ideas to check into. I'll see what I can find out. I appreciate it.

 

Also check your battery ground. I had a misfire and it started jumping around. Turned out it was the ground wire that went from the fender to the battery had seperated itself

 

I’ll check that too. I could only hope it’d be something so simple, but I’ve seen bad grounds cause all sorts of problems. Thanks

 

Also consider the CPS. Ecu compares crank angle progression against time to determine is a misfire happens. Failing cps’s can give bad data and result in misfire reports. Usually accompanied with poor running and crank nostart, often intermittent.

 

I’ll third the ground strap theory. There are ground straps from engine to firewall that help with the coil pack’s performance. Also a ground strap from trans housing to frame. Seen that one broken on several peoples trucks here. There are other grounds for other systems that also can conduct for the coils and the trans, but not as effectively, hence the additional straps you find around the truck. When current demand goes up, ability for the current to flow is limited by the broken ground straps and has to find another, less efficient route.

 

Ignore my previous msg that was related to the older COP coils.

A misfire code is determined by seeing a slow down in the crank rotation (micro second level). Many things can cause this. A different code is set when the IGF signal (i.e. a signal that the coil sends back to the ECU to confirm that it fired) is not received after commanding a spark (P0351). The ECU will stop the injector for that cyl when this happens to prevent cat damage. A misfire can occur due to a coil that did not fire, as a failed coil can also fail in a way that did still sent an IGF signal. A misfire code does NOT mean that a coil didn't fire. It only means that the cylinder combustion did not occur OR the ECU thinks that is didn't occur due to seeing a slight slow down in the crank rotation.

If your grounds are bad enough to create this level of misfires, I suspect that you would be seeing all sorts of other issues going on. Not saying that a bad ground won't create these kinds of problems, as they definately will, just saying that it would be odd to affect ONLY the coils.

 

There should be grounding to each coil pack for each cylinder, trace that wiring back from each coil and see where there might be a master ground for the entire system. Just read (on a different problem)
where with 4 wheel drive Tundras, if the ground strap is missing or loose on the transfer case , folks have had problems with switching back to 2 wheel drive after being in 4 wheel. What ever
the outcome, please get back and let us know what your findings are,,inquiring minds like to know.

 

Link to what I mentioned above about 4 wheel drive
https://www.toyotanation.com/threads/ground-strap-replacement-and-4x4.1779960/

 

Don't know if the OP has made the fix and not gotten back, but thought this little tidbit might help,,maybe.

https://www.tundras.com/threads/p0393.153651/

 

I was gonna say the torque converter can cause misfires on cylinders closest to it, which in this case sounded possible until he said every cylinder lol..

 

The OP last post was 11-12-24. Few months back,,either he fixed the problem or he's just driving something else and forgotten
about it . Been in many of these forums over the years with every different ride I've owned , and each one I see too many
folks ask for help and never get back to answer how or what happened to make the fix that solved their problems.

 

Update to those who've tried to weigh in on this issue. The truck has been sitting, and I haven't had time to mess with it. I recently ran into a gentleman who works on Toyotas at his home shop. He's had it since yesterday and has seen misfires on 1,3,8. Swapped coils and plugs. Went to 4,6,8. He thought 4 and 6 were interesting, but today he said no change, so still not conclusive. He's going to start checking grounds, etc.

 

Hope that he can find the problem for you. So many things now a days to have to chase to make things run smoothly. I really miss sometimes just having to figure out between spark, air and fuel along with timing.
I added the post about one gent with the wires pulling out of the cam sensor,, one could run around in circles for months before finding something like that. Good Luck

 

The fact that it is sporadically misfiring on different cylinders would tell me it's probably electrical..

 

I look around a lot over at the other forums, found something that really fit with what your ride was doing.
Over on Tundra solutions ,,3rd page in. Back in 2015 ,,2011 tundra with 5.7 misfire. The last of the statements are below

Update. I took it to a local mechanic. He said it was the module before the fuel pump. It's a little 4x6 black box on the driver side frame that's next to the gas tank. He said it was losing voltage to the pump. It started up at 12v then when it started chugging it would drop to 4v then when it would go down to 1.5v and stall. This was of course causing a lean/ misfire code. Part is $300 from Toyota and no parts store can seem to find it.

Guess that only Toyo store will have the part,,in 2015,,300 bucks is now what kind of money,,

Full write up below