i have a 99 civic with a d16y8. its been having some idle issues when sitting in nuetral or with clutch in, the idle will bounce from 1000 down to 200 up to 2000 and so on. Its throwing the p0505 code, but the iac valve is brand new. the throttle body is newer.

just for background purposes the car has new iac, both 02 sensors, timing belt, aem cam gear, aem fuel rail, new cap n rotor, oem exedy clutch. and i was told a newer throttle body. short ram intake, dc headers with a 2.25 exhaust to a factory muffler.

I read up on the code, but nothing is really jumping out, that i have done to try and fix it. anyone have any ideas?

 

take a look to your timing first to see what happend with light gun ...you must have a person to try keep the idle stay around 800-1000rpm not above take a look and tell me again ....also if there is a case to connect any connect wrong ?i know some connectors is same type and you can mess take a look at timing and tell me

 

ok ill take a look at it tonight. my problem im having is the rpms will bounce way up over 1500-2000. and case? not sure what you mean.

 

Sorry took so long, I did timing today I have dizzy turned all the way and its bout half a degree or less off but running a lil better. It was origionaly half way to the tdc Mark. The idle still fluctuates a lot. Any ideas?

 

Check tps and see if it needs to be adjusted

 

If you have the distributor turned all the way theres something wrong...check for vacuum leaks and check that "newer" TB especially if it's not on off of a d16y8

 

yeah check for leaks and also check plugs mine were loose lol and they caused the rpms to bounce up and down lol

 

Ok still having problem, can't find any leaks, iacv is clean, plugs are all good. Coolent is full still looking for ideas. How do you adjust the Tps? I may be looking at the wrong part I can't see any way to adjust it.

 

why the hell are people telling you to check your plugs and coolant? thats retarded. You have a code p0505 which is idle circuit problem. You need to check that there is battery voltage to the iacv, make sure there is a good ground. If those are good, you need to make sure there are no vacuum leaks, injectors are all sharing the same amount of load, and that mechanical timing is right. basically if the idle circuit has correct power and ground, there is an a/f ratio issue at idle which the iacv is trying to compensate for and cannot.

 

I guess ill have to redo the timing. I know that's off a little. Previous owner put on a new belt and adjustable cam gear. I used a timing gun and saw it was a little off.