Low fast idle on cold start causing charging problem

[wuwei37405]

My cold start RPM's peak at about 1500 and settles at about 1100, almost immediately.

[Normand]

I appreciate your frustration with having to repeat your message three times. I apologize for not listening. Still, based on my 2005 Aveo LS, your RPM's are not low. Is there anyone out there with a different opinion?

wuwei,
I'm very sorry being rude with you. I apologise... You take your time to answer to my problem with your own experience with this car.
Many thanks to you and your confirmation of RPM level at cold start.
Anyone else with a fast idle level at cold start?
Regards,
Normand

[Normand]

My cold start RPM's peak at about 1500 and settles at about 1100, almost immediately.

Mine is about the same (1450 sometimes 1500), but it's only when it goes higher than 1550-1600 that regulator switch to ON and charge the battery. I did lot of tests and these RPMs were taken with precision, slowly increasing them.
WEIRD!

[Normand]

I did Google a lot of sites for the 'baterry light ON at start and OFF after throttle increase" and find cases of guys (or their technicians) who did changed the alternator (including the regulator inside of it) and the problem came back. I don't want to change it without confirmation that's the real solution.
Anybody knows how to adjust fast idle speed at start to have higher RPM peak for the fisrt second?

[petrified.rabbit]

I say replace your coolant temp switch? only because it is not setting high idle like you want.

honestly though, i dont think my car peaks at 1450 on cold start. i do get about 1100 high idle for a short short time, and then it drops down to about 900. I have an 09 though. How quickly do you expect the alternator the charge the battery. many alternators dont give more the 13v at idle... if you start driving sooner an not idle the car to warm up the issue would go away.

also if you replaced the belt, great, but if you didnt do the tensioner, would you expect it to tighted the alternator contact for slippage?

[Normand]

Rabbit,

when the belt was changed, the problem didn't came back for ~ 10 days. At this time, I did suspect some slippage from alternator or tensionner, but my mechanic said he checked these parts when he changed the belt and they were OK.

Now, with your hints of 1450 RPM at start is normal, I will try to investigate the feet/min from main pulley, belt and alternator to find out any slippage caused from bad tensionner, seised bearing, etc...

By the way, if I press gas pedal after start, everything works perfectly with charging system: 14.6 volts at battery and if I put a load (head lamps), the alternator drops only at 14.4 volts. So, I said to my wife to kick the pedal if she leaves the car running for a while after starting it (it was cold here few weeks ago...)

Thanks,
Normand

[petrified.rabbit]

sounds like a tension issue to me then, if adding speed fixes a problem>

it seems to only occur on initial start up idle, then the issue does not return?

[Normand]

sounds like a tension issue to me then, if adding speed fixes a problem>

it seems to only occur on initial start up idle, then the issue does not return?

yes,
only on first COLD startup. At this time, I got 1400RPM for 0.5sec, then 1100 and when the motor is hot few minutes later, 900.*

If I start cold, shut motor off after 2 secondes and then start again, the peak at startup is ~1800 for 0.5sec and the regulator is switched ON and alternator charges the battery even if the motor is cold. All subsequent startups are OK. If the motor is stopped for few hours, the problem is back for the initial startup.

Maybe some bearings are seized (in alternator or tensionner or other pulley) and at the first startup some slippage occurs...but why the idle peak at 1400 on first startup and 1800 at all subsequent ones???

Normand