Rough idle after battery disconnect
Thread Starter
Instructor
Joined: Jul 2016
Posts: 109
Likes: 9
From: Northern NJ
Rough idle after battery disconnect
I've noticed that whenever my battery dies (long overdue for new battery) or when I disconnect battery cable the RPM would dip (feels like stalling) and surge back up to normal.
This seems to happen after a revving it up in neutral or when I take my foot off accelerator when coming to a stop.
Is there an engine idle relearning period that the ECU goes through?
This seems to happen after a revving it up in neutral or when I take my foot off accelerator when coming to a stop.
Is there an engine idle relearning period that the ECU goes through?
Cruisin'
Joined: Jul 2019
Posts: 21
Likes: 3
Replace the battery. You're killing your alternator at the same time, unless you're looking to replace that too. It's not designed to support all of the electrical on its own, or continually charge a dead batt.
The ECU does have an "engine cycle" for smog purposes. Not sure if it learns an idle, but I don't think so.
Cars used to die on the road when the battery was dead but the alternator was still good. My guess would be that everything almost stalls in your car until the alternator takes over. A nice safety implementation, but again - just replace the battery. PS - why would you disconnect the battery while running?
The ECU does have an "engine cycle" for smog purposes. Not sure if it learns an idle, but I don't think so.
Cars used to die on the road when the battery was dead but the alternator was still good. My guess would be that everything almost stalls in your car until the alternator takes over. A nice safety implementation, but again - just replace the battery. PS - why would you disconnect the battery while running?
Thread Starter
Instructor
Joined: Jul 2016
Posts: 109
Likes: 9
From: Northern NJ
Replace the battery. You're killing your alternator at the same time, unless you're looking to replace that too. It's not designed to support all of the electrical on its own, or continually charge a dead batt.
The ECU does have an "engine cycle" for smog purposes. Not sure if it learns an idle, but I don't think so.
Cars used to die on the road when the battery was dead but the alternator was still good. My guess would be that everything almost stalls in your car until the alternator takes over. A nice safety implementation, but again - just replace the battery. PS - why would you disconnect the battery while running?
The ECU does have an "engine cycle" for smog purposes. Not sure if it learns an idle, but I don't think so.
Cars used to die on the road when the battery was dead but the alternator was still good. My guess would be that everything almost stalls in your car until the alternator takes over. A nice safety implementation, but again - just replace the battery. PS - why would you disconnect the battery while running?
After each revving up of engine and instead of going to idle, the RPM drops to 400-500 causing a shake / stalling sensation.
I was just assuming that car goes through relearning / cycle test, upon each resetting of ECU (battery disconnect).
Senior Moderator
Joined: Apr 2010
Posts: 48,309
Likes: 9,175
From: SoCal, CA
You can pull the clock fuse to also reset the clock as well.
It does do an ECU reset when you disconnect the battery
https://acurazine.com/forums/third-g...-happy-747662/
It does do an ECU reset when you disconnect the battery
https://acurazine.com/forums/third-g...-happy-747662/
Have you tried something like the procedure below?
https://acurazine.com/forums/third-g...set-sm-948953/
Ok OP here's the procedure: (Skip Step 2 since your ECU is already reset or if you want to reset it again via the Pedal procedure then proceed.)
1. Make sure all electrical items (a/c, audio, lights, etc) are off.
2. Reset the ECM/PCM (pulling the power by unplugging the battery works well).
3. Turn the ignition switch ON (II), and wait 2 seconds.
4. Start the engine. Hold the engine speed at 3,000 rpm without load (in park or neutral) until the radiator fan comes on, or until the engine coolant temperature reaches 194 F (90 C).
5. Let the engine idle for about 5 minutes with the throttle closed. (NOTE: if the fan comes on, do not include its running time in the 5 minutes.
1. Make sure all electrical items (a/c, audio, lights, etc) are off.
2. Reset the ECM/PCM (pulling the power by unplugging the battery works well).
3. Turn the ignition switch ON (II), and wait 2 seconds.
4. Start the engine. Hold the engine speed at 3,000 rpm without load (in park or neutral) until the radiator fan comes on, or until the engine coolant temperature reaches 194 F (90 C).
5. Let the engine idle for about 5 minutes with the throttle closed. (NOTE: if the fan comes on, do not include its running time in the 5 minutes.
Thread
Thread Starter
Forum
Replies
Last Post
neil0311
5G TLX Audio, Bluetooth, Electronics & Navigation
1
Oct 9, 2018 10:25 PM
TL_TypeS
2G TL (1999-2003)
7
May 3, 2006 03:46 PM