I have a '99 with 2.0L engine.

The idle stumbles but only with multiple electrical accessories on (rear defog, lights, blower fan).

Voltage with engine off is 12.8, engine on and no accessories is 14.55, and this drops to 14.25 when I turn on the accessories.

Think this is enough to cause the idle problems or would it be something other than the alternator?

Its a Denso and certainly doesn't look new-

I've cleaned the throttle body and associated parts, also replaced the MAP sensor and did not correct the problem. Then I noticed its only with the accessories on. (Duh, well in N. ID in the winter they are always on!)

thanks, Al

 

the voltages are within normal ranges,did it just start acting up do you have an advance or auto zone near you they can check alternator out if its easy for you to take off not sure if they can test on car. have you cleaned the battery terminals,idle air valve .

 

my numbers indicate its not a voltage issue under load or not, can Autozone tell me any more about my alternator?

I've read about alternator pulley clutch malfunctions pulling down the idle, could this be it?

Cleaned the IAC motor with the throttle body, course it could still be malfunctioning

Had a EGR code so replaced all those components, no more code but still idle issues

I Do have a mystery vacuum hose not shown in the routing diagram, shares the down low to the right manifold port with the brake booster hose and ends up top left near the firewall with fitting with hole and all but nowhere to hook up to - plugged this and had no effect - Am I missing something?

Very loose alternator belt, tightened with no effect except no more terrible squeal when hit the rear defrost button -

No, haven't even looked at the battery, who's bright idea was it to hide it behind the inner fender? PO said he had just bought a "used" battery and installed it-

Here's my plan:

1. Check battery, clean terminals and ground connection
2. Remove alternator belt and check alternator pulley and idler pulley for binding
3. If above checks out, try to do a diagnostic test of the IAC motor

sound like a plan?

 

auto zone should be able to check alternator out ,where i live they have a machine to check alt's and starters out,yeah have to agree about the battery location pain in the butt to get to.sounds like a good plan to follow, it just might be somewhat normal for car only have a 132 hp on the 2.0 all those things on at idle plus if your using front defroster that kicks in the a/c compressor all cause major drain on engine