JK takes longer to start when cold

Ghstrydr

Ghstrydr

JK Enthusiast
Joined
Oct 20, 2020
Messages
215
Location
Princetown, NY / Largo Fl.
I recently replaced the battery in my '08 Sahara and have been noticing that it takes longer to start when cold. The engine will spin for a second or two before starting. I don't remember this prior to replacing the battery. When the engine warm it starts instantly. I did a reset of the ECM to see if anything would change, I understand it will take awhile for the ECM to relearn my driving habits. It could also be that I just didn't pay attention before and with the new battery is spins with more gusto. Any thoughts?
 
Ghstrydr said:
Good question, if I remember correctly it was a bit higher. Possibly 780CA to 800CA
Click to expand...

A cold engine will spin over a little slower but as far as the electronics that make the engine start shouldn't be any different. Unless the cold or dampness is causing a problem with the grounds or another connection.
 
  • Like
Reactions: Chris and mrjp
BLACKJKU said:
A cold engine will spin over a little slower but as far as the electronics that make the engine start shouldn't be any different. Unless the cold or dampness is causing a problem with the grounds or another connection.
Click to expand...
The interesting thing is it is spinning faster and a bit longer on cold starts with the new battery. Again, it just may be me, just thought I would ask in case someone else had experienced this. I will give the ECM time to learns the increase in cranking amps and see if there is any change.
 
  • Like
Reactions: mrjp
From what I dug up it looks like the standard CCA for the '08 wrangler is 600, I now think the battery I took out had 800 CCA, however it was not working to full capacity. I installed a battery with 700 CCA. I am sure if any of this would increase the speed of the starter spinning over the engine on cold start ups along with the longer spins times other then the battery that was replaced was not putting out full amperage. Yep, I am looking way to deep into what could be a non-issue. That's seems to be my nature:rolleyes:
 
  • Like
Reactions: mrjp
The speed of the starter turning has nothing to do with the amps, just the volts the battery has when it starts. That's why a battery with low or no volts usually isn't enough to turn the starter to make it run.
 
  • Like
Reactions: mrjp
BLACKJKU said:
The speed of the starter turning has nothing to do with the amps, just the volts the battery has when it starts. That's why a battery with low or no volts usually isn't enough to turn the starter to make it run.
Click to expand...
Gotcha, low volts, slow spin. Now with a new battery its probably sounding normal. As for the longer cold start times, there is one other thing I did replace just before the battery, I put on a stock Air Intake. The PO had a CAI installed, it took a bit of time to find a used stock one at a decent price. Not sure that would even affect the cold starts. In addition I installed plugs and wires prior the Intake and the battery, did not notice any change in startups until the battery went in.
 
Ghstrydr said:
Gotcha, low volts, slow spin. Now with a new battery its probably sounding normal. As for the longer cold start times, there is one other thing I did replace just before the battery, I put on a stock Air Intake. The PO had a CAI installed, it took a bit of time to find a used stock one at a decent price. Not sure that would even affect the cold starts. In addition I installed plugs and wires prior the Intake and the battery, did not notice any change in startups until the battery went in.
Click to expand...

No air filter wouldn't have anything to do with starting unless it was plugged up. Plugs and wires will help it start better.

I would think that as much as the ECM controls if there was a issue with something it would give you a CEL. Heck they don't even like non Mopar parts and will let you know about it.
 
BLACKJKU said:
No air filter wouldn't have anything to do with starting unless it was plugged up. Plugs and wires will help it start better.

I would think that as much as the ECM controls if there was a issue with something it would give you a CEL. Heck they don't even like non Mopar parts and will let you know about it.
Click to expand...
No CEL, all good there. Yeah, I stayed with what it had in originally, thought that would be best too. So I just went out to clean all the contacts / connectors on the battery. The positive post connector could be move with some pressure, not sure it would have any impact on the long cold starts, however, stranger things are known to happen.
 
Chris said:
Just out of curiosity, what condition are the battery terminals in? Are they snug and tight?
Click to expand...
I cleaned them before the install of the new battery, today I looked them over again to clean them one more time. When I put wrench on the positive post connector I could move it with a little pressure. Not sure this would cause any problems so I removed all the connectors cleaned them and tightened everything. No movement now😏
 
  • Like
Reactions: Chris
Well I spent most of last evening looking for info on intermittent long crank times on startup and I came across some folks experiencing the same condition with relatively new 2014 wranglers (at the time). It turned out to be their Camshaft Position Sensor. Even though I have an '08 with a different engine, it may be early signs that my camshaft sensor is starting to fail. Any thoughts?
 
Top Bottom