Misfire Problem - Could use some help

[sakoluvr]

My son had the same misfire code for cylinder 3. I swapped out coils with #1 but after 15 miles of driving #3 lit again. The engine ran great until it was at operating temperature and then would really shake with an obvious misfire, not just the CEL.

Plugs are a couple of months old when we did VCG. Wires have 40K on them.

He picked up a a factory fuel injector from the dealer since it was in stock and we wanted to get the truck back on the road with no down time. That new injector did the trick.

I know folks say to replace all of them but we felt there was no need right now. It runs great again.

#3 was pretty easy. We just removed the throttle body and front fuel line on that rail. The rail pivots at the back and lifts up.

I will say this, there was no mistaking that misfire with that kind of rough idle.

 

[Camps]

Hey guys, Greg here. Totally appreciate all the insight both Tim and you guys have given.

Everything Tim has said is spot on:
150,000 miles
CEL code (P0301) is still on after new injectors, plugs, wires, and coil swap.
no driveability issues or rough idle. Runs smoothly

Could it be that there might be a micro head gasket leak and a tiny amount of antifreeze is leaking into cylinder 1? my reservoir isn't showing any signs of a leak, and no white smoke out of the exhaust.

This issue has been going on for like 5 years. I used to be able to clear the code and run for about 50-70 miles before popping again. Nowadays, I can go about 20 miles before popping the code. The main issue for me trying to fix this now is because I can't get it smogged. Clearing the code and driving enough to get data takes more than 20 miles.

Hoping the A/F sensor does the trick....

Any other clarifying questions i can help with? Again, really appreciate everyone's help!

 

[mtbtim]

Hey guys, Greg here. Totally appreciate all the insight both Tim and you guys have given.

Everything Tim has said is spot on:
150,000 miles
CEL code (P0301) is still on after new injectors, plugs, wires, and coil swap.
no driveability issues or rough idle. Runs smoothly

Could it be that there might be a micro head gasket leak and a tiny amount of antifreeze is leaking into cylinder 1? my reservoir isn't showing any signs of a leak, and no white smoke out of the exhaust.

This issue has been going on for like 5 years. I used to be able to clear the code and run for about 50-70 miles before popping again. Nowadays, I can go about 20 miles before popping the code. The main issue for me trying to fix this now is because I can't get it smogged. Clearing the code and driving enough to get data takes more than 20 miles.

Hoping the A/F sensor does the trick....

Any other clarifying questions i can help with? Again, really appreciate everyone's help!

Hey Greg, we can do a leak down test on that cylinder if you want. I went ahead and bought you a downstream sensor too. That rear sensor is on me. My treat.

I'm helping this guy Tony with a big job on Sunday but will take a break from helping him to get your sensors swapped out. On another day, if you're still having the misfire, we can do the leak down test and other things to narrow down the possible causes. We also have the opportunity to grab that ECU from the guy parting out his rig on Tacoma World.

 

[LittleCaesar]

Hey guys, Greg here. Totally appreciate all the insight both Tim and you guys have given.

Everything Tim has said is spot on:
150,000 miles
CEL code (P0301) is still on after new injectors, plugs, wires, and coil swap.
no driveability issues or rough idle. Runs smoothly

Could it be that there might be a micro head gasket leak and a tiny amount of antifreeze is leaking into cylinder 1? my reservoir isn't showing any signs of a leak, and no white smoke out of the exhaust.

This issue has been going on for like 5 years. I used to be able to clear the code and run for about 50-70 miles before popping again. Nowadays, I can go about 20 miles before popping the code. The main issue for me trying to fix this now is because I can't get it smogged. Clearing the code and driving enough to get data takes more than 20 miles.

Hoping the A/F sensor does the trick....

Any other clarifying questions i can help with? Again, really appreciate everyone's help!

If you have never lost coolant, you can rule out the head gasket. It sounds like the CEL is triggered after the 4Runner goes through one, if not two or three drive cycles.

Since this is a passive misfire, and doesn’t effect drivability such as a bad coil, injector, plug or wire would, then one has to believe it is a sensor. But without hard data evidence, one is just firing the parts cannon, though if your sensors are original, at this point it will help with gas mileage with new ones.

 

[thegipper]

You can do the leak down test for peace of mind but as caeser said, if you're not having to add any coolant, your HG is probably fine.

 

[kolelt]

I quickly glanced through the thread. So forgive me if this has been asked. Have you checked the resistance on the fuel injector?

 

[mtbtim]

I quickly glanced through the thread. So forgive me if this has been asked. Have you checked the resistance on the fuel injector?

Yes, we did that and the injector tested fine. But, we replaced all 6 injectors with refurbished ones.

 

[4Reak Show]

Leak down test for sure. See what that warrants.

The cups for valve spacing rotate while operating. Super rare and very difficult to identify but it's possible there's a "bad spot" on one of those cups and it takes awhile for it to rotate back around to the bad spot and cause the problem again. That still seems far fetched but something to ponder.

I've seen it a few times where the cylinders around the firing sequence of the culprit cylinder are actually the issue. For example: firing order 1-2-3-4-5-6, if number 2 or 6 has an issue the computer might pick it up as number 1 and flag it incorrectly. Rare but it happens. Especially considering the Cam sensor is just on one sprocket.

Also, this is a waste spark system. Meaning, if the companion cylinder has an issue then the spark is going to fire into the "easier to fire" cylinder. I forget which is paired with 1 but that cylinder having an issue will cause the spark to NOT fire in 1 under compression as it should.

What I'm getting at is to check beyond just the one cylinder.

Other inexpensive items to change or check:

Cam sensor and sprocket
Crank sensor and reluctor wheel
Igniter (ignition module)

Don't forget, you need to test the component while the misfire occurs. Otherwise, you'll have a hard time catching it. Think about it. If the engine runs fine, then all sensors etc are operating correctly.

Also, if you have access to a live data scan tool you can actually watch the misfire counts on each cylinder and see which cylinder is actually dropping out.

These are the issues I've spent many hours messing with and at some point a decision gets made to replace something. The time it takes to track down a problem like this outweighs the "swap-nostics" sometimes.

Good luck.

 

[I_bRAD]

Did you check your charging voltage?

 

[mtbtim]

Did you check your charging voltage?

We have not.

 

[mtbtim]

Leak down test for sure. See what that warrants.

The cups for valve spacing rotate while operating. Super rare and very difficult to identify but it's possible there's a "bad spot" on one of those cups and it takes awhile for it to rotate back around to the bad spot and cause the problem again. That still seems far fetched but something to ponder.

I've seen it a few times where the cylinders around the firing sequence of the culprit cylinder are actually the issue. For example: firing order 1-2-3-4-5-6, if number 2 or 6 has an issue the computer might pick it up as number 1 and flag it incorrectly. Rare but it happens. Especially considering the Cam sensor is just on one sprocket.

Also, this is a waste spark system. Meaning, if the companion cylinder has an issue then the spark is going to fire into the "easier to fire" cylinder. I forget which is paired with 1 but that cylinder having an issue will cause the spark to NOT fire in 1 under compression as it should.

What I'm getting at is to check beyond just the one cylinder.

Other inexpensive items to change or check:

Cam sensor and sprocket
Crank sensor and reluctor wheel
Igniter (ignition module)

Don't forget, you need to test the component while the misfire occurs. Otherwise, you'll have a hard time catching it. Think about it. If the engine runs fine, then all sensors etc are operating correctly.

Also, if you have access to a live data scan tool you can actually watch the misfire counts on each cylinder and see which cylinder is actually dropping out.

These are the issues I've spent many hours messing with and at some point a decision gets made to replace something. The time it takes to track down a problem like this outweighs the "swap-nostics" sometimes.

Good luck.

It's diagnosing things like this that let's me know I still have lots and lots to learn about auto mechanics. I've got to get myself some type of live data scan tool at some point. Maybe I'll start looking for an old Window compatible laptop and get that tech stream program.

 

[DaMonkey]

It's diagnosing things like this that let's me know I still have lots and lots to learn about auto mechanics. I've got to get myself some type of live data scan tool at some point. Maybe I'll start looking for an old Window compatible laptop and get that tech stream program.

game changer. i recently mentioned scope to you.

my old man dropped off his OT truck (5.3 vortec) for me to trouble shoot a misfire. 0300.

- fuel; check.
- ignition; check.
- compression; check. kind of.

compression and leak down only tell part of the story. today i put scope on battery voltage and second trace on #1 ignition signal from ecu to flag #1 sync. crank starter motor only.... when the starter pushes compression, it sinks voltage on the battery so you can actually check 'relative' compression without pulling a plug. just by looking at a trace of voltage. take a look at below chart. i added 3rd data line in excel with a trigger algo to show TDC (the gray hashes). can you see what's going on? answer below pic....

either a sticky lifter or sticking valve on #5. (1-8-7-2-6-5-4-3). it passed compression because sometimes valve shuts and it gains compression, sometimes it doesn't. with x-ray vision you can record it and watch it in series and see it's intermittent.

with a low amperage clamp on a scope it even opens more options up. i mentioned that mine is very inexpensive hobby stuff, but it works great. i'd be happy to send you mine to give a try, but this one is windows based and really you should cut to the chase and just throw down. i'm not sure which one i would get, there are a lot of good options for automotive, it's all pretty low frequency.

if i was in your area, i'd be happy to nerd out and help trouble shoot that issue.

 

[heat]

It's diagnosing things like this that let's me know I still have lots and lots to learn about auto mechanics. I've got to get myself some type of live data scan tool at some point. Maybe I'll start looking for an old Window compatible laptop and get that tech stream program.

Or an OBD2 dongle and some software, less than $20.

 

[DaMonkey]

Or an OBD2 dongle and some software, less than $20.

pretty sure that's where the 0301 code is coming from. that's the end of the odb2 road.

 

[heat]

duh

 

[mtbtim]

game changer. i recently mentioned scope to you.

my old man dropped off his OT truck (5.3 vortec) for me to trouble shoot a misfire. 0300.

- fuel; check.
- ignition; check.
- compression; check. kind of.

compression and leak down only tell part of the story. today i put scope on battery voltage and second trace on #1 ignition signal from ecu to flag #1 sync. crank starter motor only.... when the starter pushes compression, it sinks voltage on the battery so you can actually check 'relative' compression without pulling a plug. just by looking at a trace of voltage. take a look at below chart. i added 3rd data line in excel with a trigger algo to show TDC (the gray hashes). can you see what's going on? answer below pic....

either a sticky lifter or sticking valve on #5. (1-8-7-2-6-5-4-3). it passed compression because sometimes valve shuts and it gains compression, sometimes it doesn't. with x-ray vision you can record it and watch it in series and see it's intermittent.

with a low amperage clamp on a scope it even opens more options up. i mentioned that mine is very inexpensive hobby stuff, but it works great. i'd be happy to send you mine to give a try, but this one is windows based and really you should cut to the chase and just throw down. i'm not sure which one i would get, there are a lot of good options for automotive, it's all pretty low frequency.

if i was in your area, i'd be happy to nerd out and help trouble shoot that issue.

I did a search on Ebay and low and behold a guy is selling an old Dell laptop with techstream loaded on it. I picked it up for $150

[MENTION=127339]4Reak Show[/MENTION], if you make it to our next party on Nov 3rd, maybe you could give me and anyone else who's interested a quick class on using the software.

 

[4Reak Show]

Yeah that'd be fun. I'm pencilling in for that date. Not a firm yes yet however... Anyway I don't have much experience with tech stream but it's supposed to be the best option. If I can figure out standard Snap on stuff that should be cake.

Best way is to graph the data. Then you can review any part of it and see any minor or slight hiccups in the major sensors etc. good call and a great investment.

This is going to open up your world of the tech universe for these rigs. You seem to have a damn good grasp of the mechanical side. Pair that with mastering the software and there are no limits.

 

[LittleCaesar]

And this is the side Tim where mechanics and the like don't take enough time (working flat rate doesn't help here) and instead open up the parts cannon, hoping for a fix. With enough working knowledge of Techstream, you will become a master.

With such you can see now if the A/F sensor is lazy, reading out of range, low voltage, etc. No more need to throw darts at the dart board.

 

[curryT4R]

The Techstream software really is the best way to go. It made things so much easier in the shop that i had i get it for myself even after i left the dealership.

 

[DaMonkey]

The Techstream software really is the best way to go. It made things so much easier in the shop that i had i get it for myself even after i left the dealership.

I'm not familiar with Techstream. It looks like Toyota specific access to ECU. What does it do for you? How would you use it to pin down this 0301 code? What are any other benefits?