#3 misfire problems

9

96-Runner

New member
I pulled the spark plug out and did the spark test against a grounded part of vehicle and have no spark coming out of plug. coil is good wires are new ( just replaced in feb.)

Looked at wiring diagram in book and chased the wiring for that coil pack and it has led me to 2 spots and neither are looking good.

The igniter and ecu are suspected culprits and need to know how to test these to figure out if they are the problem.

Im going to get a new plug as its burned up and replace wires and see if that works but I feel not
 
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new plug and wire same result. i need get this thing running properly as soon as possible without payin the mechanic $90 for diag.
 
Ok. Let me get this straight.

You replaced the PLUG AND WIRE, and are still getting a P303 code?

I think you have cylinders mixed up. There is no wire on Cylinder #3. It's a Coil on Plug design, and feeds into Cylinder #6.

Cylinders are like this, and firing order is 1-4, 3-6, and 5-2

5 6
3 4
1 2
Front​

Replace coil pack, and report back.

Rare that the ECU goes bad in these trucks.
 
I had similar issues and it turned out to be the injector. Does it run fine cold and only act up when warm ?
 
I usually have this issue with #5 on both of my 4Runners. I've changed injector once but it is usually resolved by changing the coil boot.
 
I'm getting the 301 code on mine. I've tried and swapped everything except the injector. Yesterday I installed IK22 plugs and within 15 minutes of driving the light came on again. The engine runs the same with or without the light on.
 
I had a P0304 error, I did a full tune up and swapped the coil packs and I still was getting the P0304 error. Mine ended up being a bad fuel injector. Got that replaced and it is running great now.
 
So know I know what proper cylinder 3 I tried injector noid light test and both were good. Decided pull plug and ran into major problem. There is caked on baked stuff around plug and threads inside head. Cant tell if oil or not. Any ideas?
 
This is the spark plug from cylinder 3

This is the picture of cylinder 3 spark plug
 

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Try to take a pic of the coil boot. If the boot goes bad it will not fire correctly. Get a pic inside the hole where the spark plug is if you can. I've had this problem on both of my runners on plug 3 and 5. I've changed boots before to fix it, a coil another time and an injector yet one more time between the two vehicles. Boots are cheap: $15 or so.
 
Last edited:
96-Runner said:
So know I know what proper cylinder 3 I tried injector noid light test and both were good. Decided pull plug and ran into major problem. There is caked on baked stuff around plug and threads inside head. Cant tell if oil or not. Any ideas?
Click to expand...


If you're saying you're using a test light to check the injector, this is all wrong man.

The injector is measured in resistance.

It should be between 12-18ohms, IIRC.

Don't know if I posted the video already, but if not I will tomorrow.
 
used noid light 2 check circuit and 9v battery on injector.
sorry 4 typos my phone is bad for doin this.
i replaced plug and runs fine 4now and no CEL.
sparkplug boot is clean and new
cant get picture of gunk in the sparkplug tunnel.
going to do compression test when sun is up and will report back
 
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