pooby1992

I've got a '98 Prelude SH I just picked up. It is throwing a code P0172 - System Too Rich

It also has an idle issue. When starting the engine I have to feather the gas pedal a bit to get it going. If I turn on the AC, the idle will drop until the engine shuts off.

I can keep it running with the AC on by adjusting the idle screw at the throttle body but then it is idling around 2k at a stop light.


I've owned plenty of Hondas but this is my first Prelude and actually my first DOHC VTEC Honda.

The seller said something about the car having these problems after he had the timing belt replaced a few months previous. The belt was done at a Honda dealership (have receipt) so it would seem unlikely they would mess that up, but I guess anything is possible.

I can reset the timing belt if I have to but I'd prefer to check everything else first.

Any ideas?

gstrudler

If the timing is off, that could certainly lead to both problems. You can check the timing fairly easily by pulling the valve cover and checking the marks on the cam gears, then checking that against the flywheel (there's a rubber plug you can pull off on the front of transmission below the distributor that you can use to check timing). The idle problem could possibly be a bad IACV as well. You can pull the plug on it (it's on the front-middle of the intake manifold) and see if the idle changes (it should drop a little).

holmesnmanny

Check the idle control valve for a blocked filter. You should never ever need to adjust the idle control screw on the front of the throttle body. Now you need to adjust it back.

Do a search for "setting base idle honda"

pooby1992

Thanks!

I had totally forgotten about that plug on top of the trans.