Car stalls when idle
 

This weekend we had trouble getting my 2004 RX-8 started. My husband figured out that he had a loose connection to the battery. The cable just wouldn't get tight enough on the battery post.
He cleaned off the terminals and got an adapter so that the battery cable would clamp tighter on the post. We recharged the battery with a separate charger after reconnecting it.

Now the car stalls intermittently at idle. It starts just fine and it runs fine. The power is good and there's no CEL. However, when I stop at a light and put the clutch in, it frequently stalls. I can watch the idle. If it stays about 500 RPM, it's fine but it's idling very rough and sometimes drops below 500 at which point it shuts off. Each time it restarts right away with no problem. I've been trying to keep my foot on the gas each time I take it out of gear so that it won't stall but that's a challenge with only two legs ;)

We did not have this problem prior to the battery being disconnected. I know it's supposed to re-learn or re-set itself but it's been 2 days now and there's no sign that it's figured out what RPM it's supposed to idle at.

Any idea what could be causing it? Obviously it's no longer under warranty so I'm not bringing it to the dealer. But I do have a mom and pop shop I could bring it to if necessary because we're only capable of doing the simple stuff.

Note: there are no aftermarket mods on this car - it's all original stuff.
Thanks in advance.

Give it a couple of more drive cycles before doing anything. Sometimes it does take a few times to re-learn the fuel trims and will stall out or attempt to stall out. But......it does usually go away after just a few times.

When you say two days......it doesn't matter how many days. How many times has the car been started and stopped(shut off) in those two days?


I guess you could try the 20 brake pedal stomp and see if that helps out?

If not familiar then................
1.) Turn car to "on", but do not start.
2.) Tap the brake pedal real quick about 20 times or until the oil gauge needle sweeps to the right and back to the left.
3.) Turn the car "off" for 5-10 seconds.
4.) If the gauge didn't sweep, then start over at step one. Keep doing these steps until it does sweep.....maybe tap brake pedal faster?
5.) When done, start as normal. Now...........you just performed a reset so the car is going to re-learn the fuel trims, so don't be surprised if it doesn't want to idle real well(and even stall), this will go away in just a few drive cycles.

If it continues much after about 3-4 drive cycles then we will have to start thinking other things may need to be looked into.

You sure there is no film or oil on the wire that is in the adapter or the terminals? Is this the ground cable? Rx8 have poor factory ground. You need to clean it and reclamp.

Thank you for the suggestions. We'll try them.

The car has already been through at least 9 start->drive->shutoff sequences since the battery was fixed. This morning it didn't stall going to work but the idle was still very strange whenever I disengaged the clutch (i.e. it would bounce around between 500rpm-1000rpm and it was running very rough at low rpm's and also I kept giving it gas so I didn't stall at the traffic lights.

I appreciate the advice. I was not familiar with the brake pedal stomp thing. What exactly does that do?

Hi,

I'm having the same issue. Can you tell me what you did in order to fix this problem?
Thanks,
Brandon

the fix is all about letting the ECU relearn the fuel trims.
You can also take out the MAF and clean it

Yes, it appears that in this case, time heals all wounds. I waited about 3 days and the ECU finally learned. There were quite a few stops and restarts (especially if you add up all the times it stalled) but it did eventually learn and has been running fine ever since.