Car tries to die when headlights on/heater on, any suggestions?

[DanMan7]

Hey everyone. I recently purchased a 92 Geo Metro. It was sitting awhile, so the battery is low. Barely has enough cranking power to start the car.

When the car's running, and I turn on the headlights, or turn the heater on max, the car tries to die. Could this be caused by a low battery by chance? Just curious. Could it be the alternator?

I'm going to charge the battery in the morning and see if it continues to do that same thing. But I would appreciate any input any of you might have with what could be causing the problem.

Thanks!

Dan

[HannabilRox]

Could be one of two things. Either the alternator is bad, or, there is an idle-up solenoid that causes the idle to raise when there is an electrical draw (headlights coming on, air conditioner, etc.) Regardless, I have a strong feeling the alternator is bad and not charging the battery properly.

[Crvett69]

alternator is working, when you turn headlights on it puts a load on the engine and slows it down. there is a idle valve on the back of the intake that sounds like its not idling car up when is senses a load, if you look for a rubber plug or hole on the drivers side of the tb you will see a screw back in a way. if you turn screw out while engine is running it will increase the idle speed. don't mess with the screw and nut that mechanically holds throttle slightly open

[DanMan7]

That changes the entire idle though. Then when my headlights aren't on and heater is not on, the idle jumps up to like 1200. Shouldn't the idle be compensated if any accessories are turned on?

Also, I had the car preinspected at the smog test only center. Only thing that failed was the timing. It was set to 0. I readjusted it to 5btdc as per specs, with the two terminals touching together as it said to do. Runs better now.

Just wish I could get the idle speed fixed, so that when the headlights turn on or anything else, the idle won't go down.

Dan

[hot_sd]

Sounds like a problem with the idle up system as others have mentioned. The blower fan and the headlights specifically require the idle up to work. The other one is defogger. The ECM is supposed to adjust the IAC automatically (this is for the 2000 1.3L which is what I have). I know that the 1.0L has a different system for adjusting the idle and the fuel injection is TBI - not multiport. Whatever is applicable to your car the ECM should be capable for automatically idling up the car and sounds like that is not working. Check all the wiring to the IAC (or applicable device) from the ECM. ALso check the diode module for problems.

[DanMan7]

Sorry it's been so long to answering this thread, but where is the diode module? If there is any problems with it, where can I get a replacement module, preferably new? Any ideas? I'd appreciate any help any of you could give me. Thanks!

[DanMan7]

Well I did a lot of work to my Geo on Wednesday (yesterday). I waxed the entire car (looks much much better now). I added on custom 12" wheel covers, and Geo mudflaps. Put on "Back to Black" rubber restorer on my bumpers. Looks much better than it did previously. Also was able to adjust the throttle sensor correctly. However, I did notice that there is no nut on the screw for the idle stop adjustment. Only thing I'm worried about is after a certain amount of time couldn't that screw move on its own if it doesn't have a nut holding it securely? Next time I'm at Picknpull I will grab a nut for it.

I did have to turn the idle stop screw out a little so I could adjust the throttle sensor correctly. Had to then turn up the idle screw on the side a little, but it runs better now. Still shakes, but not as bad now since it idles at around 850-900 (a little high but it doesn't shake as much), and around 800 or so with the headlights on.

I have until November 10th to get the car smogged. I will probably have to take it in and have someone fine tune it so they can make sure the idle and timing are correctly adjusted. Until then, it is running better.

[frets14]

DanMan, I recently purchased a 1989 Metro that wouldn't hold a charge. I knew the solution immediately since I had had the same problem on a different Metro. There is a connection to a fuse link located right behind the battery that consistently corrodes and will not allow the charging alternator to supply voltage to the battery. Check that out before you go any farther.

[DanMan7]

I replaced the alternator with a new one a little while ago. Alternator has 14.4 volts constantly when the car is running, the car is charging adequately. I already had checked the fuse link panel under the hood and it looks fine.