Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community - FT86CLUB - View Single Post - Battery boiling over causing misfire cyl. 2 on track.

Open Loop · 08-04-2021, 08:54 AM

I have a 2013 FR-S with nearly no engine modifications other than a Jackson Racing Oil Cooler (SSC autocross setup).

I was in my third 20-minute track session last night when the car suddenly developed a steady misfire. The car immediately went in to "limp mode" with the SLIP light illuminated, and the CEL blinking.

When I stopped in the paddock I had a little smoke/steam from under the hood. I went looking for coolant or oil, but it turned out to be a boiling over battery. In 30 years of car ownership/shadetree work I have never had a battery boil over. I have never had a voltimeter reading from this car that was unusual, but I also don't look at it when I am on the track.

The battery is a cheap one I bought from Wal-Mart, which I suspect may have been my mistake here. However, even with the boiling-over event, the battery continues to work fine.

I checked the codes and got P0302 - misfire in cylinder 2 (front passenger cyl.). I frequently get this for a bad coil, but bad coils from heat have always run pretty well at idle for me. This was definitely a complete failure to get spark/constant 3 cylinder firing situation. I decided to make the 50 mile drive home and it was on 3 cylinders with CEL blinking the entire way.

I let it sit for a couple hours, and changed Coil 2, and it still ran on three cylinders.

This morning, I decided I better through some baking soda all over the quadrant of the engine bay where the battery is located. There's quite a bit of battery acid juice in that area of the car, but nearly all of it has dried. After doing that, and to my surprise, the car started running on 4 cylinders. Yay! I intend to give it a good rinse later today.

I am interested in whether anyone knows what is causing the loss of spark from something getting wet in that quadrant of the engine bay, or otherwise having liquid or battery acid causing a "short" that would cause the car to lose spark like that.

Thanks in advance!

08-04-2021, 08:54 AM	#1
Open Loop 2013 FR-S Whiteout / SSC Join Date: Aug 2016 Drives: 2013 FR-S Location: Pennsylvania Posts: 107 Thanks: 60 Thanked 43 Times in 26 Posts Mentioned: 4 Post(s) Tagged: 0 Thread(s)	Battery boiling over causing misfire cyl. 2 on track. I have a 2013 FR-S with nearly no engine modifications other than a Jackson Racing Oil Cooler (SSC autocross setup). I was in my third 20-minute track session last night when the car suddenly developed a steady misfire. The car immediately went in to "limp mode" with the SLIP light illuminated, and the CEL blinking. When I stopped in the paddock I had a little smoke/steam from under the hood. I went looking for coolant or oil, but it turned out to be a boiling over battery. In 30 years of car ownership/shadetree work I have never had a battery boil over. I have never had a voltimeter reading from this car that was unusual, but I also don't look at it when I am on the track. The battery is a cheap one I bought from Wal-Mart, which I suspect may have been my mistake here. However, even with the boiling-over event, the battery continues to work fine. I checked the codes and got P0302 - misfire in cylinder 2 (front passenger cyl.). I frequently get this for a bad coil, but bad coils from heat have always run pretty well at idle for me. This was definitely a complete failure to get spark/constant 3 cylinder firing situation. I decided to make the 50 mile drive home and it was on 3 cylinders with CEL blinking the entire way. I let it sit for a couple hours, and changed Coil 2, and it still ran on three cylinders. This morning, I decided I better through some baking soda all over the quadrant of the engine bay where the battery is located. There's quite a bit of battery acid juice in that area of the car, but nearly all of it has dried. After doing that, and to my surprise, the car started running on 4 cylinders. Yay! I intend to give it a good rinse later today. I am interested in whether anyone knows what is causing the loss of spark from something getting wet in that quadrant of the engine bay, or otherwise having liquid or battery acid causing a "short" that would cause the car to lose spark like that. Thanks in advance!