Last Friday while idleing engine started missing/sputting. Tought my Cat may be plugged. Gutted that, not it. Thought ignition problem, so replaced a coil and swithed them around, also switched some wires, replaced the plugs. No Joy

Got a Code Reader, 1st said misfire on 3 and 6, replaced what I think is the coil on top of #6, then code moved to #2 cylinder (misfire). Checked that plug and moved the coils around again and its still missing and throwing the code for misfire on #2. So I have given up, guess its going to Toyota on Monday to see if its something small that I am missing. All the plugs look normal and clean.

Exhaust does smell a little rich.

Any ideas???

Can anyone tell me with cylinder is which. Assume the front right is No 1 the left front is No 2, etc. Is this correct?

 

Also assuming after I get this fixed the computer will throw a code from the o2 sensor telling me cat is not working... Are there and tricks to get this to stop? I fixed this on a my EVO by having the computer reflashed. Hints/help?

 

I'd put in factory plugs first, then check and make sure you're not getting a mis-fire through one of the boots on the coils. The coils themselves rarely go bad, we usually see spark tracking through the rubber, on to the spark plug tube.

 

exhaust probably smells rich from unburned fuel when it misfires. make sure you put the correct oem denso or ngk plugs in first , others may not work correctly. clean the maf . it could be a bad wire but i doubt it with it changing cylinders like that . should not have gutted the cat for sure.

 

Well after it moved from Cylinder 3 and 6, I moved wires from 1 to a different set and it didn't move. Agree with the unburned fuel, but the plug is not wet. Is no 2 the left front?

Why do you say not gut the cat? Done this on several other vehicles, improves fuel mileage, improves power, and it doesn't fail inspections here. Why do you say I shouldn't have done that? Honestly I thought this problem was because the cat was plugged, it sounded like it was.

 

And I did replace plugs with the OEM type. It had what looked like Iridium plugs..with fine tip on them?

 

The cylinders are numbered:

REAR
5 - 6
3 - 4
1 - 2
FRONT

Are your new plugs dual ground like this?

 

better check your injector i had number 2 went out on me

 

No the OEM parts said they were normal Champion plugs, nothing special.. But I took out the self cleaning type, very fine tip on them...

 

I put in some injector cleaner on Friday, have done about 45 miles since then. This all started a few miles after I filled up. Could it be bad fuel or trash that got in that injector? Will it clean itself..

Guess I will have to take off the plenum on top to get to the fuel rail and injectors.. What else has to be taken off to get to that injector?

Need one, completely out of ideas here.

 

I have had the MAF sensors throw codes before, its not happening now.. At least I don't think thats it...

 

the 3.4 motor requires the dual ground electrode plugs!-denso or ngk are best. With a gutted cat you'll throw codes and it is required to pass smog, considering it has everything to do emission control. 1,3,5 are on passenger side 2,4,6 are on driver side of motor. urd has a rear o2 simulater to trick the computer to think the rear is giving a good signal.

 

That's too bad, the factory cats are about $800-$900 new. To get rid of the code P0420 this usually works: http://www.urdusa.com/index.php?cPath=66_170

Yeah most people start with plugs for a misfire code. The dual ground make them last longer, since the 5VZFE uses a waste-spark ignition system. More on that: https://www.yotatech.com/forums/f2/e...h-bank-177019/

 

Heard that--You just threw away at least a hundred dollars in precious metals.......

Anyways--as far as figuring out the problem it sounds like we need to start at the beginning again and work our way towards the harder items.

****We need mileage and anything else you can tell us about the rig*****


**Miss fire--check for spark---maybe use a node or something to see if it is sparking consistently

**Sweep the usual sensors--a graphing scanner is the best (~80 from Under Dog Racing--used with laptop)

**Make sure the spark plug wires didnt get mixed up after your first switch

**Vacuum leaks??

**Check out the injectors

**Leak down and or compression test....if we still cant figure it out.

 

Well went to Toyota this morning, they recommended that I replace spark plugs, Wires, and the Coil that I got from Autozone. They said ONLY use toyota and for some reason they are aware that the reman parts don't seem to work correctly... I am thinking now that it has been a bad spark plug wire from the start, possibly that AND a coil has gone bad... AND the wires and plugs were not OEM from the get go.

Toyota wanted almost 600 to do 1 coil, plugs, and the wires... I told them to pack sand basically. This doesn't take any longer than an hour to do... I KNOW, I did it several times over the last 3 days...haha..

Thanks to all of you that tried to help, I have been paying attention and taking notes and learning.. This may not fix the problem though.. I will update later tonight.

Background, motor had what I thought was a lifter tap (could of been sparking on the head from bad wire), one of the plug boots was melted to the plug on No 1, tapping is gone. Truck has 210k miles, but seems to run well otherwise, no smoke, doesn't use oil, etc.

Stay tuned, I may need more advise later.

 

If that doesnt fix it, it very well could be bad gas, you said you just filled up when this started? I once got a tank of bad gas in my Taco, ran like crap and engine light was on but nothing i could do as i was on a trip. Just ran it as far dry as i could and refilled with good gas, still had to change plugs when i got back due t the motor running crapy for a while, also my MPG is still about 2mpg worse since then so i'm replacing the front O2 censor.

 

This really doesn't get mentioned often enough as a possible source of misfire codes. I have had the same thing happen after filling up on a trip, flashing CEL started right after filling up (maybe 2-4 miles down the road) and goes away after the next fill up. I suspect old gas as I only use premium and it has less turnover (less people use it). Also the ethanol blends have a shorter shelf life, I've seen only about 90 days but I'm not sure how accurate that is.

 

Why do people go to the dealer for repairs and freak out on the cost?! IT IS THE MOST EXPENSIVE OPTION! It is the highest place for parts and highest price for labor.

 

All I can say is that I wish I made 300/hour like they said they were going to charge me. The fact of the matter in this case was that it just doesn't take that long to change plug wires, plugs and a coil. So I said no way and did myself. Is that freaking out? I think not... The dealers need to pay more attention if they want my money as I don't just throw it out the window and I do know how to turn a screw driver...

In other news, it turns out that the dealers advice may have been good. I swapped out the parts I got from Autozone for the genuine toyota parts. Started it up and wa la, running great and better than ever without the cat. Although looking back the coil that is for 3 and 6 is the middle one and I originally changed the back one, so this may have fixed the problem all along.. But now I have 2 new coils, new plugs, and new plug wires...new brake pads, good to go for another 100k miles... Love Toyota!

 

congrats.....