1991 Honda Civic

Brakes problem
1991 Honda Civic 4 cyl Front Wheel Drive Manual 40,000 miles

got a 91 honda civic hatch si
when I hold my brakes on the car goes to a really low idle about 500 if I let off it slowly goes right back to around 1000 I checked the booster and its not it, tottaly stumped, any help would be great.
April 4, 2010.

I believe your problem is the idle air control valve.

Wouldent my check engine light be on if it was bad and is there a way to test it before I just buy a new one thanks.

Apr 5, 2010.
That is a common misconception, won't necessarily happen, could just be dirty. To test it your gonna take it out of its bore, you should clean the bore and throttle body while your at it. Once you remove it your gonna have someone turn the key to the on position then you should see the pintle of the iac 'step' in and out at different lengths. If it doesn't do this then its no good

Replaced it cause I had another one around still doing the same thing any other ideas do u think this could be electrcal maybe altenator or something im lost thanks for all ur help.

Apr 6, 2010.
Check the egr valve and mapp sensor. Also check fuel pressure.