Filled up with gas, started missing and got a P0305 code within a mile

My '06 V6 Taco with 295K miles was running just fine until I filled it with gas. Within a mile of the gas station, I noticed a significant miss in the engine, the Check Engine light came on immediately, and it is now throwing a P0305 code. It has been 35K miles since I changed plugs, so I changed #1, 3, and 5 tonight, planning to change #2, 4, and 6 in the next day or so.

Anyway, still getting very sluggish performance and the P0305 code is still happening with the check engine light flashing.

Thoughts??? TIA

 

Fuel treatments are not typically the fix, but in this case you might get ahead of the game by treating the tank of suspect gas with Stabil. It's inexpensive and can help with the most common "bad gas" scenario, which is too much water in it. I wouldn't go nuts pouring stuff in there but in this case it is an inexpensive and conservative option.

If it was my truck and I thought I had bad gas, I'd siphon the tank out and replace with ethanol free premium from a big brand, high turnover gas station, but you can also ride out the Stabil-ified tank and fill up at a quarter tank with the ethanol free. If that solves the problem, you're home free and it didn't cost much. If it doesnt work, it won't hurt.

Do you smell gas or get white smoke from the tailpipe? Even if not, since you have an 06, I would consider a leak down test on Cylinder 5, in case you are dealing with a failing/failed head gasket and the gas is coincidental. You can usually borrow (with deposit) a leak down kit from NAPA/Pep Boys/etc and the procedure is simple.

 

P0305 is a misfire on cyl #5. If it was "a bad tank of gas" it would be affecting all cylinders

Try moving that coil to a different cylinder and see if the code follows

Do a chemical block test to check for a hg leak. Pressurize the cooling system, pull the plug and use a boroscope to look for coolant on top of the piston. Do you have a low coolant level?

 

I bought the gas at a high volume Mobil station. I didn't notice any white smoke, and I didn't smell gas. I am familiar with Stabil, as I have used it in my ATVs and lawn and garden equipment.

I had my radiator and all associated coolant parts replaced about 700 miles ago due to a bad coolant temperature sensor by a reputable shop and it ran fine. I had filled it up at the same Mobil station immediately after the radiator was replaced and it ran fine, and at another station in between the two Mobil fillups. I drive a lot of miles, so this was all in the past 6 days.

 

Moving the coil is a great idea! I wasn't sure it mattered, as when I replaced the 3 plugs on that side, I kept the coils where they were. At least the coil is on the "easy" side of the engine. If it proves to be that coil, should I replace just that one, or all 6?

 

Up to you. They do have some years on them if they are the originals.. if you can afford it, go for it. But for now just make sure that's the problem before you start throwing parts

 

Moving the coil moved the code to the #3 cylinder. I am also wondering if paying the extra $25 for the NGK over the $57 Durlast is worth it.

 

Great news!

Yes get a Japanese coil like Denso.

 

Yes. The extra cost of the NGK is worth it.
If you go with the duralast, install them in the nearest trash can.

 

I bought and installed the NGK coil, cleared the codes, and she runs great again! Thanks for the guidance.

 

I like stories like this.

 

I do too, especially after going 50 years without needing a OBD reader and paying over $100 to get one. The fact that I was able to quickly swap the coils and read that the error was then in a different cylinder paid for the OBD reader when it proved it was that coil, without having to drive back and forth to the parts store to use their reader.

 

I've found a $5 phone app, Torque Pro and $20 OBD transmitter to be well worth the money. That and a basic multimeter will help diagnose a multitude of issues.