My 2000 GS4 did something rather strange yesterday. I'd like your input if you have any ideas:

The setting: Its been raining a lot in DFW with 100% humidity, and we went to the mall yesterday. We entered an underground parking garage that was crammed full with cars waiting for spots.

The problem: Just as I pulled into the garage the car started to "hesitate" in gear while idling, like it was about to die in idle. It was almost as if it was not getting enough gas or oxygen. I kept the car revving higher as i didn't want it to die in a cramped garage. I decided not to risk it and left the garage. Here's where it gets strange, as soon as I left the garage the car idle was fine, no shuddering or hesitation.

The hypothesis: Could this be a result of high CO2 in the garage? It hasn't done it since.

Any thoughts?

 

You mentioned that the lot was full and cars waiting, but do you think that you were in the garage that long for the that to happen?

 

Was your a/c on? I assume it was because of the humidity outside. Is it possible that the a/c turned off when you entered the garage?

 

Its possible that the AC turned off. I can't offer any other explanations since i haven't been able to duplicate the problem. Literally, the problem started and stopped within the span of being in the parking garage. Could it be a problem of the computer with the O2 sensor?

 

i've had this happen.. and it happened recurrently afterwards.. and my problem were the contacts points on the battery terminals.. check your terminals for any corrosion or maybe a loose connection right there... ever since i got new terminals that problem i had like urs went away ... (in some cases my car cut off!)

 

I've had similar problem on my ES and it turned out to be fuel filter. It was clogged and wasn't letting gas into the engine.. does gs have fuel filter?

 

were you stopped on an incline ,low fuel?

 

There are past threads discussing low idle problems. You may want to read those. I've had similar experiences, not many, where my car would idle really low...the RPMs would almost fall flat then rise. The low idle always happens with the A/C off. When I catch it I just tap the gas pedel or turn on the A/C. A few times my car has stalled on me. Since I've replaced my battery I haven't noticed any low idle problem...then again it's Florida summer and my A/C is on all the time.

 

I was at about a quarter of a tank of gas, but not on an incline. I'll check the battery terminals and fuel filter.

So if its tied to the AC how do you fix the problem?

 

you don't. there is a flaw in the ecu programming of all GS400/430.
if the ac is off, and the headlights are off, and the car is stopped in drive the idle will drop to about 550 rpm and motor will shake a little. try it and see if you get the same issue.

two things you can do.

you can flip the headlight switch on and the rpms will go up about 100rpm and it will smooth out.

you can push the auto button and turn on climate control and the rpms will go up about 100rpm and it will smooth out.

 

thanks for the heads up about the ECU. I didn't realize it was common to this car. I'm glad i didn't spend a boatload of money trying to get it diagnosed.

 

Yup, probably the ECU