P0300 random cyl misfire - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

FRS Justin · 05-06-2016, 12:11 AM

Has anyone had a P0300 DTC and if so what was the cause...
Thanks

Jaden · 05-11-2016, 05:37 PM

Quote:

Originally Posted by FRS Justin

Has anyone had a P0300 DTC and if so what was the cause...
Thanks

It was because the spark plug grenaded...

Jaden

FRS Justin · 05-12-2016, 12:21 AM

Quote:

Originally Posted by Jaden

It was because the spark plug grenaded...

Jaden

Interesting I will pull mine tomorrow...... It has only done it once but who knows.

Jaden · 05-12-2016, 02:32 AM

Quote:

Originally Posted by FRS Justin

Interesting I will pull mine tomorrow...... It has only done it once but who knows.

I say it was because the spark plug grenaded but it was the precursor to it grenading, the cylinder wasn't really firing at all once it failed completely.

Jaden

steve99 · 05-12-2016, 04:15 AM

Are your afr ok, not running lean.
no high ltft

check earth connections
is the di injection computer securly grounded its grounded via mounting bolts

SoCal80six · 06-10-2016, 12:10 AM

Quote:

Originally Posted by FRS Justin

Interesting I will pull mine tomorrow...... It has only done it once but who knows.

Just threw that code today afr was not reading lean. Cel popped on and off for like 1 min while I was driving then went away on its own. Any ideas what could cause this or what I should look for?

guybo · 06-10-2016, 06:40 AM

Quote:

Originally Posted by FRS Justin

Has anyone had a P0300 DTC and if so what was the cause...
Thanks

There are approximately 4,593 things that can cause a P0300. We need more to work with.

You can pull everything everywhere and do a general inspection for anything broken. Check for vacuum leaks. But don't start throwing parts at a P0300, you won't fix it but you will spend a lot of money replacing good working OEM parts for shit aftermarket parts.

MirthScout · 06-17-2016, 03:34 PM

Mine is at the dealer now for P0301 and P0300; running rough and stalling out at low RPM. The first theory was the coil pack for cylinder 1. Replacing it didn't fix it. The spark plugs were replaced about a month ago. They checked a bunch of other things and couldn't find the cause. They kicked it up to Toyota and after a week got back a new theory; cylinder 1 exhaust valve spring is weak and/or damaged. They are about to start tearing down the engine to find out and maybe fix. So, yeah, it seems it can be really hard to figure out the cause. I'm not sure they've figured out mine yet.

jwvand02 · 06-19-2016, 05:26 PM

Quote:

Originally Posted by steve99

Are your afr ok, not running lean.
no high ltft

check earth connections
is the di injection computer securly grounded its grounded via mounting bolts

This is the one I had problems with - lost one of the mounting bolts to the underbody monster and didn't think it was a big deal... turns out it is.

Dru670 · 12-03-2017, 05:02 PM

Quote:

Originally Posted by MirthScout

Mine is at the dealer now for P0301 and P0300; running rough and stalling out at low RPM. The first theory was the coil pack for cylinder 1. Replacing it didn't fix it. The spark plugs were replaced about a month ago. They checked a bunch of other things and couldn't find the cause. They kicked it up to Toyota and after a week got back a new theory; cylinder 1 exhaust valve spring is weak and/or damaged. They are about to start tearing down the engine to find out and maybe fix. So, yeah, it seems it can be really hard to figure out the cause. I'm not sure they've figured out mine yet.

Figured out what the problem was?

05-06-2016, 12:11 AM	#1
FRS Justin Senior Member Join Date: May 2014 Drives: 2013 Asphalt FRS Location: San Antonio Posts: 994 Thanks: 693 Thanked 695 Times in 417 Posts Mentioned: 22 Post(s) Tagged: 1 Thread(s)	P0300 random cyl misfire Has anyone had a P0300 DTC and if so what was the cause... Thanks __________________ Instagram FT86PROJECT9S Facebook FT86PROJECT9S 710whp

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05-12-2016, 04:15 AM	#5
steve99 Banned Join Date: Dec 2013 Drives: FT86 Location: Australia Posts: 7,996 Thanks: 1,035 Thanked 4,994 Times in 2,984 Posts Mentioned: 598 Post(s) Tagged: 2 Thread(s)	Are your afr ok, not running lean. no high ltft check earth connections is the di injection computer securly grounded its grounded via mounting bolts

06-17-2016, 03:34 PM	#8
MirthScout Member Join Date: Jan 2013 Drives: Scion FR-S MT Hot Lava Location: Virginia Posts: 12 Thanks: 0 Thanked 3 Times in 3 Posts Mentioned: 0 Post(s) Tagged: 0 Thread(s)	Mine is at the dealer now for P0301 and P0300; running rough and stalling out at low RPM. The first theory was the coil pack for cylinder 1. Replacing it didn't fix it. The spark plugs were replaced about a month ago. They checked a bunch of other things and couldn't find the cause. They kicked it up to Toyota and after a week got back a new theory; cylinder 1 exhaust valve spring is weak and/or damaged. They are about to start tearing down the engine to find out and maybe fix. So, yeah, it seems it can be really hard to figure out the cause. I'm not sure they've figured out mine yet.

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