low idle?

[stu2zoo31]

ok so i have an 87 prelude si with the 2.0 fi engine. my car starts fine and everything but when i stop at a light my idle drops to around 400-500 and if i sit at the light for a minute it goes back up to 900, but it takes a while. i was wondering how i could fix this. could this be a problem with one of the sensors?
please help its kind of embarrassing when people get in my car and they ask if its going to die at a stop light.

[spiffyguido]

Is your ECU light flashing at all?

Do you sometimes have trouble starting the car when the engine is hot?

It definitely sound like a sensor problem. It could also be that your idle is set too low and the sensors are working overtime trying to compensate for it.

Have a look in the manual (see manuals section above) about setting the idle correctly. Also, check to make sure your ECU isn't throwing any error codes.

Welcome to the forums!

[stu2zoo31]

cool thanks. ill check those tomorrow when i get home from school. i will let you know if i find anything.and yes when the car is hot it is more difficult to start than in the morning when it is cold.

[spiffyguido]

Let us know what you find.

[stu2zoo31]

ok so i checked my ecu and it is not throwing off any codes. would you happen to know how to adjust the idle?

[spiffyguido]

I've attached a file from the relevant page of the 1985 Prelude Shop Manual Supplement. It applies to your car.

2nd Generation Honda Prelude Idle Speed Adjustment