Misfire in Cylinders 3 & 4

1996 Tacoma V6 4x4 Ext Cab

My truck started hesitating then finally threw a check engine light. Which was a cylinder 4 misfire. Now it just threw a 3 & 4 misfire...so I'm thinking that since both went off, that narrows down what it could be big time. Changed sparkplugs about 2 months ago...ran fine afterwards, so Im pretty sure thats not it.

Any ideas??

 

Bump. P0303 & P0304 codes.

Anybody have any insight?? I really need to get my truck fixed for work

 

Have you tried to look up the codes? Also any other clues what's going on? Hesitating all the time or under load only etc

 

The codes are misfires in both the 3rd and 4th cylinders. Happens all the time, from start to stop. No matter the load, speed or rpm. No other clues, just a standard misfire as far as I can tell. I'm inclined to guess that it's maybe a coil?! Don't the coils operate 2 cylinders each?

 

My guess would be a faulty coil on cylinder #3, or a bad ignition wire going to cylinder #4.

 

Can you explain this for me? Why one or the other? Thanks for the reply!

 

Yes, the coils do control 2 cylinders. In this case the coil would be on cylinder #3, and the wire would go to cylinder #6.

What usually ends up happening if the misfire is consistent enough and the engine ran through multiple rpm ranges, the computer will be tricked into thinking the opposite bank is also misfiring. That's why you're getting the 2 codes.

 

This might help

 

Makes sense. Would it help to know that it threw the P0304 first? Perhaps it is the 4th cylinder ignition cable. I priced the coils, they run about $70each.

 

I'd go for whatever code & cylinder came up first.

 

Switch the coils around to see if misfires move.

 

Doesn't that show that 3 goes to 6? 1 and 4 are tied together.

 

Yes...

I've seen quite a few 5VZ coils stop working on the cylinder they are on, but still sending spark to the opposite bank.

 

Sub'd

Just got a po300 & po304 on Sunday. 304 came first. I'm gonna move the coil and see if I can narrow it down

 

Then, I don't see how the diagram helps at all. He's got one cylinder misfire that has the coil, and a different pair entirely with the opposite cylinder misfiring. Educate me. What's the diagnostic value here?

Edit: I just read the thread more thoroughly and see your explanation above. I'm not sure I buy it, but I certainly don't have a better suggestion to offer.

I think I'd do as someone above suggested and swap coils around, clear the codes, and see what you get.

 

I've had this before too and switched the coils with the same results. What worked was putting dielectric grease in the spark plug boots. No more codes after that.

 

My problem has compounded.

When I was driving home from work, my temp gauge spiked. The next morning, I filled the radiator. Just today, after one round trip to work (2hrs driving) I ended up adding around 45ounces of water to fill the radiator when I got home. I also noticed my exhaust is white, and lots and lots of moisture.

I just inspected the coils, and checked the spark plus wires. The #4 wire which comes off the #1 coil was burnt up and corroded. I was sure this was the problem so I didn't bother swapping coils to help diagnose. I cleared the codes and went for a test drive.

Threw the P0304 code for cylinder 4 misfire again.

I'm sitting at Pep Boys right now debating on spending $50 on new spark plug wires to fix the misfire. Because, honestly, let's face it. Even if the misfire is fixed, it looks like there's a coolant leak which may or may not have caused the original problem. And I don't think fixing the misfire will fix the coolant leak...

My truck has 210k miles on it. I think I'm done. I think I'm ready to throw in the towel and get a new 4Runner. Ive had this truck since high school...I'm 34 now. I have a real career and the means to buy one, I've just been holding out cuz my truck is free and I don't mind driving a POS.

Maybe enough is enough. What do you guys think?

 

I say go for the 4runner but hold on to the truck if you have the space. Head gasket leak is a pain and more so with Toyotas as the mating surface has to be real smooth for the new gasket. I would much rather get a low mileage motor replacement.

 

Ouch. Overheating and low on water are bad signs. Time to get it fixed properly, or get a new ride.