low idle random no start
 

2003 Camry 4cyl., 250,000 miles.
Went out to start after picking up boy at daycare. Won't turn over. Dash lights on, headlights on, ect. Cleaned battery terminals, it started but idled rough. Took it home and put in new battery from our Toyota Sienna. It started but had the same symptoms, low and rough idle. Then randomly I turned the key and same thing happened. It wouldn't turn over. Dash lights on, etc.(lights don't dim). Then a few minutes later it randomly started again but low, rough idle again. Noticed that at low, rough idle there was a crackling, arcing sound around the ignition coils. If I rev the engine a little the sounds go away, then return when low idle. NO check engine light though.
I had a new ignition coil, so I proceeded to check each coil with the new one and no change. Started but low, rough idle again. Unless multiple coils are bad? (Had the #2 coil changed about 6mo ago but had check engine light on. low idle, wouldn't drive at all.)
Car drives fine at normal speeds , but when stopped it has the low idle.
Checked battery, 12v. Low idle at 12.5v, rev it and it's at 13.5-14v.
Woke up this morning and it barely started, cranked hard, then ran ok, but the low, rough idle resumed.
Thought it might be alternator but it seems to check out at 13.5-14v, but really haven't had it tested.
I'm really stumped. Any thoughts would be greatly appreciated!

It has happened if battery is disconnected, the cars computer needs to work things out to get back to normal.

The throttle on this engine is electric, not cable driven. If no improvement then could be a combination of dirty throttle body with a disconnected battery. Clean the throttle body as advised in your other post.

If engine ran OK prior to non-start issue caused by battery connections then suggest trying simple fixes first as such as suggested above.

Took it to Autozone. They said the battery is bad. I can't figure that out but I guess just because my multimeter said 12v doesn't mean it was good. Anyway, the guy then tried to jump me and it woudn't do anything like before. All lights, instrument panel work, connections seem fine, wouldn't start. So I'm thinking it's my starter? It did crank hard earlier this morning and when I started it to take it to Autozone this afternoon it cranked hard. Maybe that explains the random starting/not starting yesterday. Hmmm

Please clarify the following:

What does cranking hard mean?

When the starter is engaged does the engine turn over at a normal or slow pace?

Does hard starting mean the starter turns the engine over at normal pace but the engine does not start? Or the starter is turning the engine slowly or not at all?

Battery voltage should read 12.6-12.8 volt after being charged and then sitting overnight. Anything below 12.4 volt is not good.

When engine, running battery voltage should be something like 14.5-15.1 volts as the alt charges it.

The hard starting was that it started at a slow pace.
Anyway I had to leave the car at Autozone since it wouldn't start this afternoon. Went back after work to put in a new battery and no go. Banged on the starter and no go. Had the guy check the whole system and he said there was no current going to my starter. He thought starter relay. So we plugged in a new starter relay. No go. So he sold me a starter. I went home and put it in and whammo it started right up. (So I guess the starter was completely locked up.) Only thing is, the idle was low/rough still so I took it out for a spin to let the computer do it's thing. It still had a low/rough idle so I cleaned the throttle body as suggested by other posts. It was black with 260,000 miles of buildup. Started it back up and it runs like a champ! Better than it has in 100,000 miles. Should have cleaned the throttle body out a long time ago. That works like magic for the low idle.
Thanks for all the help! It's always nice to have someone to bounce things off of!

Good job on fixing the problems!

Thanks for posting back with the fixes.

Nice to hear the fix! Thanks for sharing.