99 3.4L, 135k on the clock, timing belt at 120K by PO, no idea when plugs and wires was changed last time.

the first time was on thursday, i got a CEL, went to a shop nearby, the code came up P0304, #4 cyl misfire. cleared the code and it kept popping up.

here is weird part,:

on freeway, in 5th gear, accellerating when it hits 2600rpm to 2700rpm, the CEL goes off(blinking). i tried each gear from 1st to 4th gear upto 3200rpm, NOTHING. so it ONLY happens while in 5th gear and every time.

i have an OBD-II from Autozone hooked up, each CEL indicates the same P0304 code.


so, what do you guys think?

p.s. OEM wires and plugs are on the way, but i don't think it's them causing the problem.

thanks

 

They do have alot of problems with injectors going bad. I would pull the intake and move injector #4 over to #1 and see if the miss follows

 

i took a brife look at the FSM, looks like plenty of work, plus which one is #4?

 

Start with the basics. Plugs.

 

plugs and wires will be in tomorrow.

 

it will either be a coil pack or an injector...

 

i sure hope so, because these jobs are relatively cheap. the part i don't understand is why it only happens while in 5th gear.

 

99 3.4L, 135k on the clock, timing belt at 120K by PO, no idea when plugs and wires was changed last time.

Hi,
when you said you had "no idea of when the plugs and wires were changed last"?
That was the biggest clue for me.
I have a 99' 3.4 L too. and our Plugs are 30,000 Mile max life plugs and its VERY likely your aged spark plugs, unless you have used cheap gas and have fowled out/dirty injector...?

Smart move on going ALL oem especially for the duel electrde plugs!...Watch the torque on the plugs form time to time people cheese the threads use a rubber hose to initially thread theplugs... and I like a drop of "anti sieze" spread evenly across the plug threads (easier to change next time)... good luck

 

Maybe because you have the highest load on the engine in 5th gear while accelerating. If I was an engine that's when I'd complain the most.

 

you got that right!! took a look at the freeze data log on the OBD-II, the time misfire happened, the engine load was 78% @2677rpm.

i got lucky this time because after pulling out the plugs, the #3 was a dud. even the boot was burned throu. the previous owner had some junk a$$ plugs in there. after swapped out with OEM plugs and wires, it runs like a champ. if don't know why all the code readers got the #4 cylinder misfire. one of the readers was a loaner from AZ, 2 others were from shops, one Snap-on, another was Mac.


thanks everyone.

 

first, i checked sparkplugs.com, couldn't find the OEM spec. wires, i even called them, the answer was the OEM direct replacement wires are not available for wholesale. i got a hold of RAFA@NTP(Northrage Toyota here in Los Angeles), he got a good deal, $65 to my door include all 6 plugs and wire set, tax, shipping. great guy to deal with.

 

I learned that when I was just a little goat riding my bicycle hehe, 2nd gear was harder to peddle than 1st gear. We only had 2 speeds back then (sting ray).

 

YO,
I love it when the fix is easy....Spark plugs!!! Man I KNEW IT!! 65 Bucks for plugs and a wire set is a good deal I have 155K on my runner and the original wires and it runs great. Its smart for you just to change them out prevents drama down the road...
I think I'll change the wire set at 185K...Not bad.

 

this is a picture of the burned plug

 

Your wire is more than likely burnt up the boot the same way. It will run ok for a bit after replacing the plug but will start missing again soon. The wires will most likely need to be replaced as well

 

i didn't take any chances with the old wire set, they were replaced along the plugs.

 

thats a nasty spark plug. congrats on fixing your problem. it feel better to drive? i did an oil change on mine, went from 20w-50 to 10w-40 to see what would happen, and it feels like a totally different truck. night and day difference. then i put new plugs in, put the reccomended 22RE single diode plugs in, and it feels great to drive. you get that feelin too?

 

Seriously--I just had the same code--#4 cyl misfire on my '98 Limited--177k miles. I didn't think the plugs were due, but they were--about 60k on them (my, time flies..), and the wires were original. LOTS of hesitation, especially on acceleration. Replaced the plugs and wires, the CE light is now off, and the car runs GREAT!!!

 

Ozzy, what was your reason for using the 3.0 dual diode plugs in the first place??
just for the heck of it??
J/w btw

 

okay so check it out, i have the same problem. p0304 read. i was looking at the wires and everything noticed that the coils are 1 per 2 cyl. after reading a bunch of threads it doesnt sound like its going to be a very expensive fix at all. tomorrow i will try and put in some new plugs (starting at the basics) ive had the truck since 12k there is 109 on it now. no wires or plugs have been changed oops! so i will try out just plugs, then wires and last but not least the injector cleaner.