i have a 91 honda with a d15b7 with the dpfi i tryed a couple of things but i cant get the idel to stop jumping between 1000 and 1500 does anyone have any clue or ides what i can do i wana but an exaust on it but not with it doing that lol

 

well u gotta let people know what u did so we dont suggest the same things... Id suggest these few things,

Iac valve
Intake mani gasket
throttle body gasket...

if its not idling too bad maybe jus adjust the idle screw...

 

i already meesed with the idel valve and reset the codes no new codes came up

 

if ur not throwing a code then its not electrical... its gotta be a vacuum leak somewhere... get some carb and choke cleaner and with the car running spray the carb cleaner on the intake mani where the gasket goes, if the car idles up high then u have a leak in the gasket...do the same with the vacuum hoses and u should find the bad one

 

Clean the IACV (see link in my signature), check for intake air/vacuum leaks, bleed the cooling system of possible trapped air, and check the Fast Idle Valve (Correction -- I don't think the 91 Civic dpfi has a fast idle valve):

 

Fast Idle Valve may be busted. This happened to me, but caused much more severe idle surging... yours may be not as busted as mine was though.

Unbolt the FITV from the throttle body. If coolant comes out of the FITV from any of the air ports, it is busted.

 

If none of those suggestions work unplug your Coolant temp sensor while the car is jumping and see if it goes away if it does replace it its only 20-30 bucks, I tried everything and that finally fixed it. I'm not sure where the sensor is on the 1.5 motor, it has two wires going to it, may be on the side of the block under the distributor (That's where mine was I have a 1.6), attached to your thermostat housing or at the bottom of your rad.

 

on the thermostat housing i believe.

 

Thanks for them tips as I am having the same issuse. I was wondering about your fast idle vavle being busted...Did you purchase a new one?( where at and what kinda of $) Thanks.

 

Actually, it's the two-wire sensor located below the distributor. The coolant temperature switch that controls the radiator fan is located in the thermostat housing.