Toyota 3.4L Engine Misfire Diagnosis

[@jamesdodson9417]

Well done youngster good to see the next generation of real mechanics in the making and not parts changer . Way to work it out . I love seeing this .

[@bearpawtimber8739]

Great info on troubleshooting buddy. I'm chasing a P0303. Looks like I'm headed for those dreaded injectors.

[@johnaustin2276]

Just went through this with my 97 4runner. Coil packs and injectors and all good. Do not cheap out on the coil packs. I bought a set off Ebay (OEM) and only 60$, well they were garbage so get good parts.

[@Miles-wy1zr]

Brother I bought a 1995 tacoma with this engine. The engine light pops up once in a while and the previous owner told me just to erase it once it pops up. I know the truck ain’t running right. Jiggles a bit and feels sluggish. Added redline fuel cleaner to see if that helped. Still runs the same. When I looked in the truck I saw what spark plugs he put on. They fit the truck but it’s not the dual electrode ones. He put after marker ignition coils and wires too. Code p0300 p0301 p303. Gonna clean up the MAF sensor when i get home. Luckily I got this truck for free. Lol.

[@rustbucketproductions]

Looks like you have done some good analysis on the problem so far. Hopefully you can get down to the root cause and fix it.

[@FD-rh6tr]

I'm chasing a P0305 myself and ruled it to be the fuel injector. I chose a different plan and decided to rebuild all 6 injectors with an eBay rebuild kit and see if the misfire will go away (and also if it will run smoother). A multimeter will also determine if the fuel injector #5 it bad itself. Great video!!

[@rustbucketproductions]

Thank you and yes you are correct, checking the resistance across the injector is a good place to start. Hope the fix goes smoothly.

[@DylanRossyErazo]

my coil pack went bad, changed . problem got a little better . misfiring, but least it started. changed injectors. ($700) . same shit. all this time the ignition cables where connected wrong

[@lukeboudreaux8781]

Hey man, I want your input on this. Just bought a 2002 4runner, the plugs were replaced recently. I was driving it to work, about 290 miles into the drive I had a flashing CEL, I had some vibrations right before it came on almost like I was on a bumpy road. I kept driving(shame on me) because sound, feel, and temp was normal. About 30 min later it turned back off . Any clues on why it would happen? I was driving about 75 on cruise control. Thanks!

[@rustbucketproductions]

I had something similar happen when I first had the issue. The misfire then became constant every time I drove the car. I would recommend pulling the codes from the CEL and seeing what cylinder misfired. You can swap the coil pack of the misfiring cylinder with a good pack to see if the pack is bad before moving to the injector.

[@rustbucketproductions]

One more addition thing is look at the plug of the misfiring cylinder for any discoloration or gap out of tolerance.

[@lukeboudreaux8781]

@@rustbucketproductions thanks!

[@lukeboudreaux8781]

@@rustbucketproductions what would that discoloration point to?

[@jessbloomfield2163]

thank you for this, my toyota tacoma just had this happen the other day, p0301, last year replaced the cylinder coil so wondering if its spark plug or fuel injector

[@rustbucketproductions]

Glad it helped!

[@leoszilard3998]

Changed the OEM wires at about 40K on my 3.4L 4runner (That were working good)and went through 2 sets of aftermarket low resistance(About1K ohm per foot)wire sets and both sets did not last more than 20K miles and they both threw P0304 & P0302,It turns out that the wire insulation cracks and near the top of the boot where the wire makes the 90 degree angle and then arcs to the ground ring on the top of the cylinder where the boot goes into.Most engines do not have a metal sleeve where the plug goes down into and that sleeve transfers lots of heat to the boot and wire.Word to the wise,The two sets that failed are the Bosch premium wire set(Black box)that lasted a year and then a code thrown and engine not running right,And a set from B&B manufacturing called Platinum class laser mag,Lasted 3 years.Stay away from these wires as these are not good quality.