dgl4runner

Okay so i recently bought a 98 sr5 4runner and it was ideling rough so i went and got the codes checked at auto zone.. pulled up random cylinder misfire. so the guy recommended changing fuel filter and plugs to start off with.

I changed the fuel filter and plugs today drove around for a bit and the problem seemed to be fixed. I was sitting at a stop light and the check engine light came back on and started blinking.

Went back to auto zone got codes checked again. The codes came up for cylinder 1,3, and 5 misfire.

Are the coil packs going bad or does anyone have any history with this?

SPL15

could be bad gas or weak fuel pump. In my experience if you have misfires on cylinders that are on the same coil pack it could be the coil pack, but if you have random misfires throughout the cylinders its unlikely all your coil packs are dead.

I havent dug too deep into how the 5VZ engine works, but im guessing it has an Ignition Control Module (ICM) that fires the coil packs. Random problems could be caused by this too.

But everytime I have experienced random misfires from random cylinders not connected to the same coil pack its been a problem with either bad gas, water getting into the gas, or a weak/dying fuel pump.

It would be unlikely that all 3 coil packs are bad, but ya never know. Whats your fuel pressure? How old are your coil pack wire sets? This can cause these types of issues too if your wires are arcing to ground.

The misfire has to be caused by either no spark or no gas. Since it is random I would guess its something that is common to all the cylinders such as Fuel delivery or ICM.

vital22re

iTrader: (2)

what kind of plugs did you install? obd2 toyotas are really finicky about spark plugs and plug wires.. Make sure you use oem tune up parts. The motors call for special plugs. i picked up a set for 2.99 a piece for my 3.4.

dgl4runner

well the problem mostly happens at stop lights when im idling then when i start to drive the check engine light goes off.

i put denso plugs in it from autozone

Ive gone through at least 4 tanks of gas since i got the runner and the only time the light never came on was when i put injector cleaner in the tank, but as soon as that tank ran out and i filled up again the light came back on.

Adam F

Try new plug wires. You can get a set of NGK at rockauto for like $25 or something.

Also make sure you have the dual electrode plugs. They are REQUIRED.

pat161

I second checking the plugs. I went to the dealer for plugs and all they had were the NGK, I wanted Denso so I ran to Autozone. He brought me 6 plugs, which luckily I opened to check and they were single ground. I asked him to double check the part and he turned into a dick and said he had never heard of Toyotas needing the dual ground and the part he got was all they had. I politely thanked him for wasting my time and left, moral of the story is don't assume the parts guy knows what he is talking about.

dgl4runner

yea i put the dual elctrode denso plugs in.

Ok well last night i pulled out the fuses to reset the comp. to get rid of any old codes. I then drove 3 hrs from memphis to nashville and the engine light never came on but when i got off the interstate and sat at the stop light the check light came back on so maybe this is a fuel pressure or some type of airflow sensor?

alotawatts

My 2001 came from the factory with Denso plugs on one side and NGK's on the other ...not uncommon I hear. Anyway I changed my plugs at aprox 32k miles. The Denso's were more worn out....weird...I always use Denso parts in my Honda. 4Runner got all new NGK's .

mlombardi

I have the same problem with a 98 4runner with a 3.4. Ichanged the wires and plugs and the problem went away for three weeks. Another thread stated that you are not supposed to gap the dual ground NGK plugs but I did and it ran fine. I noticed that my coil packs smelled like burnt plastic when I took them out. I think I'm going to change them as I have 115000 miles on the rig and I believe they are the origional coils. Next i'm going to clean the MAF and change the fuel filter. Anyone have any other suggestions? This misfire problem comes and goes.

eddieleephd

Di-electric grease is to be used in the drop tubes to help with this issue it is best if you can use one of the pointed spouts to reach in the tube and get the spring not just squeeze it in and plug the tube.. some times as well the springs get compressed and they need to be stretched back out.. I figured this out he hard way..

mlombardi

I love that idea about pulling the springs back out a little. I wonder if there was arcing inside the tube and this caused the burning smell. I will try that next. Cleaned out the MAF sensor and the throttle body bu still have the same rough idle. Going to try some injector cleaner in the gas tank also.

Thanks for the help and quick reply

mlombardi

Tried new gas and injector cleaner in the tank and checked the new plugs (they look okay). Wonder if it's a coil? That's next on the hit list. If the plug in unit at advanced auto parts says random misfires does this rule out an o2 sensor ?

eddieleephd

Dude I had this issue I am telling you to test the coil packs resistance per FSM
http://www.ncttora.com/fsm/index.html
and if they test fine what you need to do is Use NGK or DENSO wires and use a bit of DI-electric grease on the plugs to assist with contact Di-electric is neither conductive nor impedes it stops corrosion and improves the contact of the spark plug to the spring... if the misfire does not improve on the CYL with the spark plug with the coil on top of it then you stretch the springs out to improve compression and insure contact will be made!!

look up the tubes and see if you see a goo that looks cloudy yeah the manufacturer put it there and if you accidentally pull the spring out you can see it well and have the joy of using a skinny screw driver to click the spring back in the clip at the top fun and annoying little project but worth it and save 100.00 a coil pack or more

brian2sun

Here's what I get out of this:
The 3 cylinders directly under each coil pack are the ones missing and all the cylinders on the other side seem to be firing fine. This tells me it's not the wires because otherwise cylinders 2, 4, and 6 (the only ones connected by wires) would be missing.

It also tells me that it's almost positively not the coils packs because why would a bad coil pack fire one of the cylinders and not the other?

My guess is that it's the coil boots (the drop tubes that go from the coil pack to the plugs directly underneath). This would explain why the coils are successfully firing the wired cylinders on the far side and not the ones underneath. The weird thing is that all 3 went bad at the same time. My guess is that they aren't "snapped" all the way onto the plugs or they are getting loose and the connection is weak.

hross14

Guys, it doesnt matter what plugs you run--the only reason we use dual eletrode plugs is because it is a waste spark ignition system--and that means the plugs fire twice.....hence wear twice as fast--replace twice as fast......

OK--moving on--stop guessing and start testing--ohm the wires, sweep the sensors--

If you are around the 100k mark you are going to need to start replacing sensors like the TBS and O2/AFR.....clean the throttle body and clean the MAF. A dirty MAF will also cause this same problem....

And by the way--I run single electrode Denso iridiums and my motor purrs with no probs

BUT PLEASE....please stop attributing "running issues" to the urban dual plug myth.

hross14

Sorry--make that the URBAN Dual Electrode myth...

TheDurk

The 1,3, 5 thing is intriguing. Either some fault is recurring three times and only on one side, or something is affecting that side. A few ideas: Look for any loose grounds, especially on that side. Second, consider a compression test, a valve train problem on one side (sludge, maybe?) could produce those codes. Finally, what kind of shape is your TB and tensioner in? Could it have jumped a tooth on one cam pulley? I'm not sure what the result of this would be, so I could be way off base on that one.

hross14

You also need to tell us more about the RIG--miles--maintenance....etc...

Yota Doc

Change your fuel filter and also check the fuel pressure. A bad pump can cause that code. Also when you check the pressure just turn the key on the pressure should go up and not leak down. If it does yank the pump, cause the ball valve is gone, happens a lot really to most any car or truck. The way it sounds, sounds like the whole bank is running lean, thats why it is miss fireing. I havent seen 3 individual coil packs on the same side go out in a long time. good luck

dgl4runner

Ok so i started this thread a year ago and just now fixed the problem this past weekend. I finally gave in took it to a shop to get a diagnostic, ran me bout $70. After all the stores (autozone, oreilly, napa) and everyone swearing it wasnt a timing issue were wrong! The shop said it needed new water pump timign belt and serpentine belts. I replaced all this and it runs beautifully. so if you havent changed your timing belt in a while you wmight want to check on that mine was worn out. good luck with figuring out whats wrong.