Hey guys. Search isn't working well for me today.

I installed a new battery and positive battery terminal. It started fine and when I push the clutch all the way in the Rpms would drop to zero. I could get it started and it kept doing it. I did the brake reset and it did better. Now it sometimes drops to 500 rpm and will climb back up to my normal idle. The ac keeps losing power and then climbing up also. The car ran perfect besides the underpowered battery. It was in with Mazda the day before and it was given a clean bill of health besides the battery and rotten terminal. After driving it this morning it drops to about 750 rpm and climbs back to 900. Is this normal after a new battery? I had disconnected the old battery but i don't remember having this issue.

Also just remembered 2 bad motor mounts also. Not sure if that would cause the idle issue.

 

Actually.....car might be le-learning the fuel trims after battery change and/or reset, so it's possible that it may take a coomplete drive cycle or two to settle down.
But, I will tell you that bad motor mounts can cause that idle issue as well. Sorry................but that's the way it is...........not saying it's the mounts, but it could be.

 

What he said.

Besides, 750-900rpm is the normal range, so I wouldn't be worried

 

I am just glad it is starting easier with a new battery. Ill give it a bit and see if it works itself out. I was running great before the change. Hopefully it will clear up.

 

Just for the sake of argument, did you have the alternator checked when you went for the battery replacement? Just curious.

 

Yup. I removed it and had it bench tested. It passed with no issues.

 

Have the motor mounts replaced as well. Don't wait too long, or your engine will shake badly.