[sweet88gt]

Backstory is here but warning long read
Lets talk tests

What are the causes of misfires? Lets go back to basics here.

Talk to me like I have no knowledge and school me on the causes of misfires in the 3.4 V6.

At present time I have pending codes for misfires 1-2-3-5-6 Once I see these it will throw the CEL and die.
Many of the normal items replaced like spark plugs--wires--new coils--Motorwest Fuel injectors--fuel filter--fuel pressure regulator--fuel pressure 42 psi--good compression--replaced a few bad vac lines

So Im not seeing any coolant loss. I have not done a leak down test.

All I want is this thing to get fixed and I will make it a woods truck.

[Bad Luck]

You need:
1)Good compression
2)Correct amount of fuel
3)Spark strong enough to ignite (and at the correct time)
4)Correct component timing

[sweet88gt]

Originally Posted by Bad Luck

You need:
1)Good compression
2)Correct amount of fuel
3)Spark strong enough to ignite (and at the correct time)
4)Correct component timing

Seems simple enough!!!
I have been chasing this for 3 months on and off. We I get time I tinker with it.

Off the wall thoughts could be bad gas, or failing fuel pump. Im at a 1/4 tank (after those 3 months) and might be ready to drop the tank and inspect.

[Bad Luck]

Originally Posted by sweet88gt

Seems simple enough!!!
I have been chasing this for 3 months on and off. We I get time I tinker with it.

Off the wall thoughts could be bad gas, or failing fuel pump. Im at a 1/4 tank (after those 3 months) and might be ready to drop the tank and inspect.

Bad gas is a possibility. 42 psi doesn't sound like a bad fuel pump to me though. What were your compression numbers? Dry or wet?

[RandyBobandy]

Was this issue happening before you replaced all those parts? If not when did it start, and where were the parts sourced from? If you had a bad coil pack before and replaced them with something like a counterfeit eBay part being sold as genuine oem it could cause issues.

[sweet88gt]

Originally Posted by RandyBobandy

Was this issue happening before you replaced all those parts? If not when did it start, and where were the parts sourced from? If you had a bad coil pack before and replaced them with something like a counterfeit eBay part being sold as genuine oem it could cause issues.

Truck drove great for a yr then one day it stalled. Since then I have sourced info and tracked down dead end leads.

That thread above is very long but it lays out what I did step by step.

I sourced most of those parts via Toyota dealerships online and I used Yotaparts as well. I skipped Amazon.

[sweet88gt]

Originally Posted by Bad Luck

Bad gas is a possibility. 42 psi doesn't sound like a bad fuel pump to me though. What were your compression numbers? Dry or wet?

I followed the same details from Tim the guy on Youtube.

I would have to find the numbers for accurate but I seem to remember 190-200 if I recall.

[Dieselchessy]

Haven’t read the other thread, to lazy.

Have you replaced the igniter.

[sweet88gt]

Originally Posted by Dieselchessy

Haven’t read the other thread, to lazy.

Have you replaced the igniter.

I don't blame you, that other thread is long.

No I have not.

[19963.4lsr5]

I don’t like your 12.9v at idle with nothing on.

Something isn’t right.

Grounds, bad Alt, bulb in dash for charging.........


Sent from my iPhone using Tapatalk

[I_bRAD]

Originally Posted by 19963.4lsr5

I don’t like your 12.9v at idle with nothing on.

Something isn’t right.

Grounds, bad Alt, bulb in dash for charging.........


Sent from my iPhone using Tapatalk

Yeah. too low.

I had a mysterious misfire code that never actually appeared to be misfiring. I also spent quite a bit of time diagnosing. Spoiler: it was the alternator.

[19963.4lsr5]

Originally Posted by I_bRAD

Yeah. too low.

I had a mysterious misfire code that never actually appeared to be misfiring. I also spent quite a bit of time diagnosing. Spoiler: it was the alternator.

I think he should fix the voltage first. I think he is trying but can’t get the plug out of the back.


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[sweet88gt]

Originally Posted by 19963.4lsr5

I don’t like your 12.9v at idle with nothing on.

Something isn’t right.

Grounds, bad Alt, bulb in dash for charging.........


Sent from my iPhone using Tapatalk

Very true. Im looking into getting a set of brushes for it first.

[sweet88gt]

Originally Posted by I_bRAD

Yeah. too low.

I had a mysterious misfire code that never actually appeared to be misfiring. I also spent quite a bit of time diagnosing. Spoiler: it was the alternator.

I could only hope it was that easy. Fingers crossed

[I_bRAD]

Originally Posted by 19963.4lsr5

I think he should fix the voltage first. I think he is trying but can’t get the plug out of the back.


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Agreed. There's something about the low voltage that was causing mine to throw misfire codes even though it didn't appear to be misfiring. It did stall out a couple of times on me during the period I was trying to diagnose it. Mine was charging (barely) at higher RPM but only getting around 12.5 at idle.