lostchild83

Hey guys, I'm having a strange problem with my idle today. And I was wondering if any of you came accross this.

Here are some facts:

I drive an 2002 TLS with ~102k miles. My battery died on me a few days ago, and I only got around to replace it 2-3 days later. So my car was powerless for 3 days.

Today, I replaced the battery with a brand new one. I also replaced the grounds that connect to the negative terminal (the one that goes to the chassis, and the tranny)

Now here is the strange problem (its not the typical IACV problem, theres more to it):

When i'm at a complete stop, the usual IACV symptoms are there, the idle goes really low, like it will stall and then goes back up, then down and up. Now, whats different: when the idle goes low and my engine starts shaking, my dashboard's lights DIM down also. My AC wasn't on, the only thing on was my stock radio. Could that be a sign of electrical problem? My alternator maybe?

Also, sometimes I would tap the gas pedal to bring the rpm back up, but as soon as i do that when it drops, it'll drop really low and would sometimes stall.

What could cause these symptoms? Could my new battery be the cause? Could a dirty air filter cause that also? Any suggestions would be greatly appreciated!

Miro9

I'm not a specialist AT ALL (as a matter of fact I just got my TL about a week ago), but one of the pre-owned '03 I looked at seemed to have a same problem (RPM would go up and down during idling). That one defenetely had transmission shut. Once again, this is probably not what you're having, but I figured I'd share anyway. Thanks.

BLADE RUNNER

When my idle control valve went on my 02TLS the symptoms were the same. I have it checked first. What about your codes? Did you reset your idle after the battery change by letting it idle for 15 minutes?

lostchild83

update:

I tried to get the ECU to relearn by unplugging fuse #13 on the passenger side for 10sec then replugging it, revving it at 3000rpm until the radiator fan starts. then let it idle for 5min.

My idle is still weird. I noticed something though: When I was revving my engine at 3000rpm, there is a slight burnt smell coming from the left (edit: passenger) side of the engine bay. (the alternator maybe?)

Also, now, when i tap the gas to bring the rpm up, it is almost certain that when the rpm drops, my car would stall.

acutee

measure your alternator output. it has to be, I think, 14v or so. If it was alternator, your battery will die again in a week or two due to unsufficient charging.

lostchild83

Where do you hook up the cables to measure the output?

acutee

If you look at the alternator, there will be a positive terminal there. or first meature the terminal at the battery without starting the car, then measure it again when the engine is running to compare the voltage.