Misfire on Startup & Constantly Dead Battery

[brandon_5.0h]

Pull the battery out of the car, charge it and let it sit on the shelf overnight. If the voltage is low the next day then you know there’s an internal short of other problem in the battery. If it’s still holding 12.5 volts then the problem is the car.

Charge to what? 14.5? Then take it off and let it sit overnight and if it goes below 12.5 it's the battery?

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[brandon_5.0h]

Also if the battery never gets up to 12.. Its an internal failure

Once started, the car holds 14.6-7 just fine. It's when it sits it get to just below voltage to start the car. Not dead enough to make the dreaded click, but it turns over for 2-3 seconds and then nothing.

 

[brandon_5.0h]

I wasn’t having any trouble with y sensor that I know of, I only changed it because it was included with a rear seal plate kit that I purchased from MMR. I don’t think the sensors are that expensive by themselves though.

If you do decide to change yours, I suggest removing the intake manifold to access it, rather than removing the tranny, unless of course you’re do for a clutch.

I gotcha. Still looks like a pain and that's my last resort option. I'll do plugs again for the misfire before tearing apart the car. Any other idea on why it would be constant misfire on start and then go away whilst driving? Just doesn't make sense to me. Popped up at random. Wonder if it's all tied to a short somewhere in the car. I mean, it does have headers and a sub, so stuff could rattle. Thoughts?

 

[NGOT8R]

I gotcha. Still looks like a pain and that's my last resort option. I'll do plugs again for the misfire before tearing apart the car. Any other idea on why it would be constant misfire on start and then go away whilst driving? Just doesn't make sense to me. Popped up at random. Wonder if it's all tied to a short somewhere in the car. I mean, it does have headers and a sub, so stuff could rattle. Thoughts?

Have you tried swapping out the #2 ignition coil with another coil to see if the misfire moves to another cylinder? Check to make sure all of the electrical connectors for the coils are plugged in and locked.

 

[brandon_5.0h]

Have you tried swapping out the #2 ignition coil with another coil to see if the misfire moves to another cylinder? Check to make sure all of the electrical connectors for the coils are plugged in and locked.

Okay - will do this when I get home. Still doesn't help my multiple cylinder misfire on start though. Best way to diagnose that? Plugs again?

 

[NGOT8R]

Okay - will do this when I get home. Still doesn't help my multiple cylinder misfire on start though. Best way to diagnose that? Plugs again?

Verify that this boot is completely plugged up. It could be partially plugged up and causing intermittent issues.

 

[19gtMD]

Once started, the car holds 14.6-7 just fine. It's when it sits it get to just below voltage to start the car. Not dead enough to make the dreaded click, but it turns over for 2-3 seconds and then nothing.

The charge being in the 14's just means the alternator is working. But it will drop when the car is off. I have noticed my charge to fluctuate from 14.8- 15.1 through idle and light acceleration.

 

[KeyLime]

Charge to what? 14.5? Then take it off and let it sit overnight and if it goes below 12.5 it's the battery?

If you have a maintainer or smart charger let it bring the battery up to full charge. Take it off the charger and battery should settle down to float at around 12.5 volts or higher If it gets close to 12 or lower the battery has a problem.

 

[ice445]

Was it doing the same stuff before the new battery?

 

[Rapid Red]

Afternoon all,

I've been having issues with the car in the past few months and was just wondering if anyone had any insight as to what's going on here. I believe it is all tied together in some way. So, on the dead battery front, the car is randomly dying. It has died as fast as sitting at the gas station pumping gas for 2 minutes, to not even being able to sit for a day without needing to jump. I am in cold weather (32F). The car has a new battery. Disclosure: I have a dashcam, sub, and radar detector installed. These have all been disconnected once at a time MULTIPLE times to ensure there is no draw but the same issue persists. As of recently, I believe there is a loose wire or ground somewhere in the harness that may be causing the other issues. The multiple misfires (on startup and cylinder 2) are also a hit-and-miss. I ran cleaner through it and have good 93 in it. The car also has new plugs, etc. However, this started happening when the car started dying constantly. With this, I've also noticed my taillights (left and right at random) decide to not work while the other does when the car turns on after jumping. I fix this by turning all lights off and then back on to auto in the cabin.

I am truly baffled by this car and would appreciate any and all feedback that hopefully, I have not thought of yet. Thanks in advance!

You never mention if you have replaced the battery or how old it is. How about starting there?
A battery discharged in 2 mins @ fillup, me thinks the battery has some serious problems.

Shorted cells, and could very well cause a bunch of abnormal electrical glitches. Having a steady & constant power supply is important.

 

[Rapid Red]

Nope as stated. Battery stores & auto part stores NEVER charge their new batteries. I tend to test mine when i buy them. Honest it has happened to me on a motorcycle once

Fixed it

 

[19gtMD]

Fixed it

Is it fixed? What did it end up being.

 

[NGOT8R]

I thought my battery was completely dead, as I hadn’t had it on a charger since August when I disconnected it from the car. I checked it with my multimeter today and it was sitting at 12.5V. I popped the fill caps and took a look at the fluid levels. They were all at least 3/8” too low, so I heated some filtered water in a large pot to about 180 degrees, inserted a smaller pot into the large pot, and used a bowl as a lid (filled with ice) and made some distilled water which was captured in the smaller pot. I then topped off all cells and put the battery on the charger. It’s been about 5 hours now and the battery voltage is at 14.40V. I hope I’m good with this battery for at least another couple of years.

I would tend to agree with what @19gtMD said, about auto parts stores never charging their batteries. It makes sense, as they have so many batteries sitting on their shelves, it woukd be a never ending process to maintain all those batteries.

 

[KeyLime]

14.4 volts? I think you’re measuring the output voltage of your charger.
A battery isn’t going to float at 14.4. Take it off the charger and measure the voltage after an hour or so. Then you’ll have a good idea of the battery resting voltage.

And voltage won’t tell you what the battery will put out under a load.

. I then topped off all cells and put the battery on the charger. It’s been about 5 hours now and the battery voltage is at 14.40V. I hope I’m good with this battery for at least another couple of years.

I

 

[NGOT8R]

@KeyLime, let me go pull it of the charger and let it rest over night and I’ll report back by tomorrow morning.

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