3rd Gen Cylinder 6 Misfire HELP!

[jrebolloso]

Running out of ideas here and hoping someone cane help. I have a misfire in cylinder 6. What I have done:

1) Replaced plugs with NGK platinums.
2) Replaced coil packs.
3) Replaced fuel injector on cylinder 6.

After all this, i'm still getting a misfire from cylinder 6. Anyone have any experience with this issue? Any suggestions? I did have a cracked radiator back in early October that caused an overheat.

Suggestions I have already gotten that I would like feedback on as well:

1) Change oil.
2) Change head gasket.
3) Change valve.
3) Change fuel filter, clean system with fuel injector, fill up with premium.


Thank you for your ideas and suggestions.

 

[chimpy]

Have you ran a compression test on that cylinder?

 

[southsidewaterman]

One relatively easy thing you could do, just to eliminate a potential cause, would be to switch spark plug wires to see if the code moves with the wire.

I had a similar misfire, and before I changed the injector, I switched the spark plug from that cylinder, then switched coil packs, and then switched spark plug wires. The code never moved each time I changed something, so then I assumed it was an injector, and luckily it was. You've done most of that from what I saw in your post.

I would just switch it with one of your existing wires, reset the code, and see if the check engine light code pops up misfiring on a different cylinder.

 

[jrebolloso]

Have you ran a compression test on that cylinder?

chimpy, no I have not. I was thinking about doing that this weekend? Is it something I can do or should I take in for that? Thanks.

 

[jrebolloso]

One relatively easy thing you could do, just to eliminate a potential cause, would be to switch spark plug wires to see if the code moves with the wire.

I had a similar misfire, and before I changed the injector, I switched the spark plug from that cylinder, then switched coil packs, and then switched spark plug wires. The code never moved each time I changed something, so then I assumed it was an injector, and luckily it was. You've done most of that from what I saw in your post.

I would just switch it with one of your existing wires, reset the code, and see if the check engine light code pops up misfiring on a different cylinder.

southsidewaterman, great point and very simple to do. I'll probably tackle that first. Thanks.

 

[soundmanlpte]

I did all of this and it was just a wire. Make sure you get NGK wires... Those Bosch ones are crap. If that still doesn't fix it, I'd start with a compression test, then leak down test.

 

[gmv4k]

This just happened to me. You can read it here, I tried to document my whole experience.

http://www.toyota-4runner.org/3rd-gen-t4rs/175812-gmvs-build-thread-2.html#post1877117

I concluded it was a my number 6 spark plug wire. Super easy fix. Definitely check wires before changing fuel injectors.

 

[JustKeepSwimming]

Howdy - I realize this is an old thread but I'm checking in for ideas.

I have the same model as you - 2000 4Runner, v6 SR5. About a month ago, suddenly, rough running, then Check Engine. Cylinder misfires - 1/3/5. Next day, no problem. Two days later, again rough but not as bad. Later resets itself and fine. Shop replaced plugs, wires, coils (they were way overdue). Same issue. They also did a compression test and noted the 1 and 3 were below spec. But, why working fine and then not, and then working again? Seems like if cylinder pressure was the issue the problem would not self-resolve. But - I'm no mechanic.

Did you get any good ideas from your post (other than wires/plugs/coils)?

 

[gamefreakgc]

Howdy - I realize this is an old thread but I'm checking in for ideas.

I have the same model as you - 2000 4Runner, v6 SR5. About a month ago, suddenly, rough running, then Check Engine. Cylinder misfires - 1/3/5. Next day, no problem. Two days later, again rough but not as bad. Later resets itself and fine. Shop replaced plugs, wires, coils (they were way overdue). Same issue. They also did a compression test and noted the 1 and 3 were below spec. But, why working fine and then not, and then working again? Seems like if cylinder pressure was the issue the problem would not self-resolve. But - I'm no mechanic.

Did you get any good ideas from your post (other than wires/plugs/coils)?

Cylinders 1 3 and 5 are all on the passenger's side of the engine. That alone makes me think it's suspect as to why only one side of the engine throws a code. If it were coil packs, then you'd had codes for both sides of the engine as it's controlled by the same coils. Have to instead narrow it down to only things that are on one side. Potential thoughts:

1. Blockage in the passenger's side fuel rail. That would restrict fuel to just one side of the engine and throw codes. Try a few high quality fuel injector cleaners in case there's some sort of junk lodged in the fuel rail (Lucas, Royal Purple, AMSOIL)

2. One that we all hope it isn't is a cracked cylinder head. A compression test would confirm or rule this out. You can rent compression test kits at parts stores sometimes, just unplug the MAF sensor first so it doesn't flow any fuel.

That's all I can think of right now.

 

[JustKeepSwimming]

Thanks for the response. The verdict is a hairline crack in the head, based on scoping the cylinders. They didn't see it, but the shape of the carbon buildup indicates it, as well as the engine behavior. All the other replacements and tricks (switch injectors, etc) didn't change a thing. The cost to replace is stupid expensive now. Hoping that impending "recession" will change the costs.

 

[mtbtim]

Thanks for the response. The verdict is a hairline crack in the head, based on scoping the cylinders. They didn't see it, but the shape of the carbon buildup indicates it, as well as the engine behavior. All the other replacements and tricks (switch injectors, etc) didn't change a thing. The cost to replace is stupid expensive now. Hoping that impending "recession" will change the costs.

You can buy a new head and do the work yourself.

There's a guy on YouTube that made a good series for the repair. Here's Part 1 of his series.

<iframe width="560" height="315" src="https://www.youtube.com/embed/voLBRDZL9fE" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>

UPDATE

I now have my own series for this repair, and if I do say so myself, we did a better job documenting this job especially with the additional information offered in Part 4 of the series.

<iframe width="560" height="315" src="https://www.youtube.com/embed/iSFpwnCuBDk?si=g0SZCHY6uLQZWRNM" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>

 

[Sparman]

I'm in the middle of replacing both heads now. As Tim suggested, that video series is a great reference, as are Tim's videos on Timing Belt Replacement, Valve Cover Gasket Replacement, and knock sensor replacement - these are all invaluable resources and are truly "gifts" for those of us that want to tackle this project. Thanks Tim.

My experience so far: A timing belt replacement is the bulk of the work - if you can do that, you'll have all of the specialty tools required. Everything else just requires standard tools.

Fortunately for me, I live in Southern California and rust is not an issue. This made removal of the Exhaust Manifolds easy. Once the nuts are removed from both and the crossover pipe, you can use a pry bar to push the crossover back and free the manifolds.

The most tedious part so far is setting the valve lash - even with the heads on my bench. Something to point out: When you remove the cams from the RH head, you match up the "two dots" identified easily with factory match marks. On the LH head, you match up "one dots" also easily identified with a match mark. However, when you set lash, you match "one dots" - so keep this in mind with the RH head.

Also, setting the lash requires you to remove and replace the cams - several times over the course of the process. Be sure to oil the cam bearing bolts as they are going in and out of aluminum, and despite my best efforts (using a torque driver and A LOT of care, I stripped one of the holes).

Otherwise, this is not really a complicated job. Just take your time be methodical.

I've attached some pictures - one of cylinder #3 with a nice puddle of coolant on the piston, and one of the crack in the head (which looks identical BTW to the crack depicted in the video series except his was Cylinder #4). Also two of what the head and valve cover looked like - a testament to regular oil changes and Mobil 1.

Good luck!

 

[jaxinmontana]

Sparman - I have a 1997 that I put new head gaskets into, and while doing that, adjusted the valves, new timing belt, etc. I haven't been able to get it to run since. I've checked my timing marks to ensure they all are matching up (ie. both camshaft pulley marks, crankshaft pulley mark) and all looks good there.

You mention, "......On the LH head, you match up "one dots" also easily identified with a match mark. However, when you set lash, you match "one dots" - so keep this in mind with the RH head. What do you mean by this?

When I reinstalled the camshafts, I ensured that the 1 dot alignment occurred on the RH side, and two-dot alignment occurred on the LH side.

 

[Sparman]

Right, the RH head has match marks at the "double dots" - this is the proper orientation to have the cams in to remove them. However, when you set valve lash, the FSM states to have the single dots aligned, at which point you can adjust 1 exhaust pair and 1 intake pair. Then you rotate 240 degrees and do two more pairs, and 240 degrees again to do the last two pairs.

Just make sure you start checking valve clearances with the RH head oriented with the single dots matched, rather than the doubles which you may be inclined to do (since this was required to remove the cams and has the match marks, etc).

Hopefully that makes sense.

 

[Sparman]

I just re-read your post and think you have it backwards. RH head has match marks at two dots to remove, LH has match marks at single dots. **Unless things are different on a 97, this is how it is on my 02.

 

[brillo_76]

Sparman, how many miles on the head that has the crack?

 

[Sparman]

192k

 

[JC Oliver]

Multiple misfire

I have noticed misfires occurring in cylinders 1 and 2 of my 2002 4Runner. The misfires started in cylinder 1 and subsequently developed in cylinder 2 after a two-day period. The issue is peculiarly confined to instances when the vehicle is in gear, be it Drive or Reverse, with no manifestations in Neutral or Park. This weekend's plan involves replacing spark plugs and wires, but I am uneasy about potential underlying issues if this remedy fails. Have others faced analogous problems?

 

[JC Oliver]

Multiple misfire

I replaced spark plugs and cables today. What surprised me is spark plug of cylinder 5 was “loose”.
When the misfire started I had 3 codes : P0300 ( random/multiple cylinder misfire), P0301 (cylinder 1 misfire) and P0302 (cylinder 2 misfire). Today I checked again and I had 2 more codes: P0100 (mass or volume airflow sensor A circuit) and P0110 (intake air temperature sensor 1 circuit bank 1). I don’t know if those 2 extra codes appear because I insist using a car with the misfire or if something else has been damaged.
After the spark plugs replaced I cleared the memory and drive a couple minutes, the works better, but sometimes I feel the “misfire”. Tomorrow I will drive more, let ser what codes will appear.

 

[Endlessblockades]

Pardon my inquiry but you first said you were going to replace the plugs this weekend and 2 minutes later reported that you replaced them. Are you a time traveler? Please don't take offense, but I pictured Sheldon of BBT typing your first comment as I read it....