Misfires on 3 cylinders—likely evap issues, flooded charcoal canister led to misfires (2021, 75K miles)

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Did you see my post?

If you have a consistent misfire from #8 and random from the others, #8 may be the culprit and causing the others to misfire. I think chasing a cylinder pressure issue is barking up the wrong tree imho.
 
Has your windshield been replaced or is it factory?
 
studawg said:
Has your windshield been replaced or is it factory?
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It has been replaced—but it was replaced in summer of 2023 so it’s almost 3 years old and it’s seen a lot of water since then. It’s an interesting theory to consider wiring water damage, though I’d really have expected it to rear its head well before now.

dogfishlake said:
Did you see my post?

If you have a consistent misfire from #8 and random from the others, #8 may be the culprit and causing the others to misfire. I think chasing a cylinder pressure issue is barking up the wrong tree imho.
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I did and can’t provide exactly what they’ve done other than what they’ve told me and all they’ve said is they have checked and inspected the coils and they’re operating normally which was the culprit you had mentioned
 
I get that you are on the edge of the warranty and worried about something bigger not getting covered if you go rogue. I also hate firing the parts cannon but...

I'd buy an OEM coil and put it on #8. Takes very little time with a 10mm wrench. $80-100 and 15 minutes of time to rule out what looks to me like the simplest most likely cause...
 
GrouchyTech said:
Do you have the vehicle? I’m at the Dallas training center this week, maybe I can put eyes on it one evening. I brought my GTS/techsteam.
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I don't right now, it's at Family Toyota of Arlington. If they can't get it to trigger again I should be picking it up this afternoon though
 
HSTexan said:
It has been replaced—but it was replaced in summer of 2023 so it’s almost 3 years old and it’s seen a lot of water since then. It’s an interesting theory to consider wiring water damage, though I’d really have expected it to rear its head well before now.



I did and can’t provide exactly what they’ve done other than what they’ve told me and all they’ve said is they have checked and inspected the coils and they’re operating normally which was the culprit you had mentioned
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Cool. Sorry for the issues, hope you figure it out.
 
dogfishlake said:
I only skimmed over your thread so far, so it may have been covered. This is a very different Toyota (a friend's Avalon V6 around 2015ish) but was a situation I have not seen before. The engine had multiple, random misfires that would come and go, much like you are having. The dealer wanted to replace all coil packs at a pretty hefty price. I had a mechanic friend of mine look at it and he discovered it had a lone coil pack that was bad, but would ground other random coil packs out through the wiring intended for full engine shutdown- either security system trigger, or sudden crash impact trigger. That made it seem like there was a larger problem. A couple hundred bucks into one new Denso coil pack and all fixed.

Again, a very different engine and year, but still Toyota engineering. Just something to think on.

Good luck!
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Well today’s update was unfortunately more of the same—they’ve driven it 3 times so far and about to drive it a 4th and they cannot get it to trigger codes again. I screenshotted the above post from @dogfishlake and asked if they thought we should go ahead and swap coil 8 to a new one. He’s going to get with the foreman in the morning and go over it, otherwise their plan is to keep it tomorrow too for another day of test drives with pickup slated for Friday
 
HSTexan said:
Well today’s update was unfortunately more of the same—they’ve driven it 3 times so far and about to drive it a 4th and they cannot get it to trigger codes again. I screenshotted the above post from @dogfishlake and asked if they thought we should go ahead and swap coil 8 to a new one. He’s going to get with the foreman in the morning and go over it, otherwise their plan is to keep it tomorrow too for another day of test drives with pickup slated for Friday
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If it drives fine, and then doesn't, I am really thinking it isn't a compression, or quite likely, not a fuel issue. The only thing on a gas engine that behaves like that is spark. Without it, no cylinder firing.
So many things can cause that -from melted/chewed wires, bad ecu, water intrusion to harness, coil packs, etc.

That consistent cylinder #8 misfire just keeps rearing its ugly head.
 
TimCFJ40 said:
I get that you are on the edge of the warranty and worried about something bigger not getting covered if you go rogue. I also hate firing the parts cannon but...

I'd buy an OEM coil and put it on #8. Takes very little time with a 10mm wrench. $80-100 and 15 minutes of time to rule out what looks to me like the simplest most likely cause...
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If you buy it from O’Reilly you should be able to return it if it does not solve the problem.
 
BIC JET said:
If you buy it from O’Reilly you should be able to return it if it does not solve the problem.
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Thanks for this. IMO,, please don’t buy o’reilley parts and put it in our rigs (oil filters not withstanding).
 
HSTexan said:
It has been replaced—but it was replaced in summer of 2023 so it’s almost 3 years old and it’s seen a lot of water since then. It’s an interesting theory to consider wiring water damage, though I’d really have expected it to rear its head well before now.
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I dont know man, it can take a while for water to work its way down to the junction box at the driver side footwell. Considering it sounds electrical and is intermittent, and considering the issues with windshield replacements in these things, I would want to check that area for any sort of corrosion at least to rule it out.
 
studawg said:
I dont know man, it can take a while for water to work its way down to the junction box at the driver side footwell. Considering it sounds electrical and is intermittent, and considering the issues with windshield replacements in these things, I would want to check that area for any sort of corrosion at least to rule it out.
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If they call me back and haven’t checked yet I’ll be sure to tell them it had a windshield replaced and see if they’ve checked down there and if they could
 
studawg said:
I dont know man, it can take a while for water to work its way down to the junction box at the driver side footwell. Considering it sounds electrical and is intermittent, and considering the issues with windshield replacements in these things, I would want to check that area for any sort of corrosion at least to rule it out.
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I can’t really think of anything located down there that would cause a misfire. Engine management is all under the hood.
 
Just got a call from the dealership--they went to drive it and got the CEL to trigger. However, when they pulled the codes there were zero misfire codes. Instead they said it was all 5 evap codes which I've already forgotten the numbers. They want to start with replacing the charcoal canister. I had actually checked the gas cap on Saturday when I was waiting for the tow and it was tight. With the LRA I am very conscious when I fill up to not top off the tank, however, I have boiled fuel 3 different times while on trails and additionally there was one instance when I was transferring fuel and forgot to turn off the pump until it was borderline too full, so I'm curious if I've flooded the charcoal canister.

The other thing that is possible is the LRA breather vent is clogged. I've probably done a bad job at keeping an eye on that and it's been about 2 years and 35K miles since it was installed. We definitely get a lot of dust here in TX so I forwarded the below thread to my advisor to show the tech and see if we could start there before replacing the charcoal canister

TeCKis300

Thread 'Charcoal Canister / LRA Breather Fix'

TL;DR​

1) LRA charcoal breather plumbing and adapters are too small in diameter, limiting venting when filling the main tank tripping the gas pump. Needs 5/8" ID plumbing though to breather.
2) Breather filter is a maintenance item. Too much dust and dirt will plug the external breather filter, blocking the vent and main tank from taking gas.
Solution: Change breather hose to 5/8" and use a large 5/8" breather filter. Clean breather filter every 25k miles, or when gas fill speed become sensitive. More detail here


Symptoms:​

This has been awhile in the making, with a...
  • Like


Edit: Maybe a bit of wishful thinking—seems Slee had already done a nice upgraded filter and hose which looks too clean to be causing some issues

3742574695762494585.webp
 
Last edited:
GrouchyTech said:
*Especially* don’t buy the parts store coils. I see so many bad aftermarket coil packs it’s just sad.
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Yes. When we had our misfires on a cross country trip, all I could get were parts store coils because it was a weekend and we weren't near any dealers.. They cost as much as the OEM (or more) and it took two to get across the country home. New plugs and one OEM coil and all was well.
 
Didn’t some guy with an LRA find that the installers pinched some harness between the tank and frame and caused all sorts of electrical gremlins?
 
HSTexan said:
Just got a call from the dealership--they went to drive it and got the CEL to trigger. However, when they pulled the codes there were zero misfire codes. Instead they said it was all 5 evap codes which I've already forgotten the numbers. They want to start with replacing the charcoal canister. I had actually checked the gas cap on Saturday when I was waiting for the tow and it was tight. With the LRA I am very conscious when I fill up to not top off the tank, however, I have boiled fuel 3 different times while on trails and additionally there was one instance when I was transferring fuel and forgot to turn off the pump until it was borderline too full, so I'm curious if I've flooded the charcoal canister.

The other thing that is possible is the LRA breather vent is clogged. I've probably done a bad job at keeping an eye on that and it's been about 2 years and 35K miles since it was installed. We definitely get a lot of dust here in TX so I forwarded the below thread to my advisor to show the tech and see if we could start there before replacing the charcoal canister

TeCKis300

Thread 'Charcoal Canister / LRA Breather Fix'

TL;DR​

1) LRA charcoal breather plumbing and adapters are too small in diameter, limiting venting when filling the main tank tripping the gas pump. Needs 5/8" ID plumbing though to breather.
2) Breather filter is a maintenance item. Too much dust and dirt will plug the external breather filter, blocking the vent and main tank from taking gas.
Solution: Change breather hose to 5/8" and use a large 5/8" breather filter. Clean breather filter every 25k miles, or when gas fill speed become sensitive. More detail here


Symptoms:​

This has been awhile in the making, with a...
  • Like


Edit: Maybe a bit of wishful thinking—seems Slee had already done a nice upgraded filter and hose which looks too clean to be causing some issues

View attachment 4118735
Click to expand...

Plot thickens...

I can't say any of this is for sure, but the LRA can interact in unexpected ways. There's a possibility that what is happening is during an EVAP purge cycle (hence not readily reproducible). And there so much vapor and fuel going into the intake that it's causing mis-fires.

Why it's only on one bank, I'm not sure. I believe the purge valve is plumbed back into the plenum where it should be distributed evenly, but stranger things have happened.
 
If this was my car, I would have so much emotional instability lol.

From head gasket to coil pack to EVAP to electrical gremlins...

@HSTexan hang in there!
 
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