1991 Honda Accord Electrical components affecting engine pe

MICLO814

MEMBER
1991 HONDA ACCORD
4 CYL
2WD
AUTOMATIC
194,000 MILES

My 4cyl Accord (1991) runs well in the daytime with mild symptoms when elctrical components are turned on. When the care is set on drive (automatic) the rpms are lowered when I turn on the fan or keep the lights on or engage the brakes thereby turning on the brake lights. It is more dramatic when the car is being run in the cold. In fact, the when on drive the idle is greatly affected when any of the electrical components are turned on or the brakes are engaged when the weather is cold such as at night, every night. The idle (on drive) seems a bit jumpy but not to the point where I'm afraid the car will stall. I have a digital multimeter and I am trying to figure out the problem. When I set the car in park the idle is fine. Please let me know what you think. Thank you.

1 Reply

KHLOW2008

MECHANIC
41,814 POSTS

Hi miclo814,

First thing you need to do is to check the charging rate.

With engine running, connect the DVOM across the battery terminals and get the charging rate. It should be between 13.5 to 14. 5 volts.

Turn the AC on anc monitor the charging rate. It should be able to maintain the charging voltage.
Turn headlights on and chack again.

If charging rate drops below 13 v, the alternator could be weak.

The other cause is the idling system. Get the thrittle body and Idle Air Control valve cleaned and readjust the idling speed.

Finally check the valve clearance if the above does not yield any results.