weird idle problem, I can't figure it out

luvmyhondas · Post by **luvmyhondas** » Mon Jan 18, 2010 2:05 am

Car: 95 Del sol Si (d16z6 just rebuilt by me).
Mods: Intake and header right now.

Problem: The car won't idle properly. I've set the timing, cleaned the IACV, tried another known good IACV, cleaned the ports on the TB, made sure all sensors were plugged in to the correct plugs, checked for vacuum leaks, and even tried a different ECU. No CEL. When driving the car it runs great! No stutters, stammers, dead spots, surges, etc...runs like a Honda.

Car will idle for a while then starts to surge (not like PCV woogoo tho) just a few hundred rpm while slowly getting slower and slower until it dies. While driving if you clutch it (like rolling up to a stop) sometimes it will die. When the idle is steady it's rock solid 800 rpm, but when it starts it thing it's about 600 and falling. Doesn't seem to matter if it's warm or cold out. Also does it whether or not the car is cold or operating temp.

Anybody got any ideas? I really need to get this one fixed...it's killing me not knowing what's wrong.

At this point, I'll look into just about anything cuz I'm stumped.

LU_NA20v · Post by **LU_NA20v** » Mon Jan 18, 2010 2:38 am

Sounds like a vaccuum leak to me!

try building a tester and run some pressure through it. could be a intake mani gasket or something...

Idk, I don't know hondas very well

crx08 · Post by **crx08** » Mon Jan 18, 2010 3:04 am

vacuum leak for sure. have the car running and spray brake cleaner around the intake manifold too check for leaks. and around the throttle body to see if its tight enough

luvmyhondas · Post by **luvmyhondas** » Mon Jan 18, 2010 4:51 pm

I guess I'll have to quadruple check for vac leaks then. I know that's what the symptoms point to, but I've been ALL OVER that motor looking for leaks.

thanks for the reassurance.. at least now I don't feel like I'm crazy.

rickles8099 · Post by **rickles8099** » Mon Jan 18, 2010 5:25 pm

i know i dont know much about cars, but normally when theres a vacuum leak it idles higher than normal because its drawing in more air into the engine than the throttle body can adjust for.

does the car run and idle good when its cold and then starts acting up once its warmed up?

Clayton · Post by **Clayton** » Mon Jan 18, 2010 5:28 pm

fitv?

Post by **stolle** » Mon Jan 18, 2010 9:47 pm

1. jump the service plug, (its behind the passenger side kick panel).

2. unplug iacv

3. start car, it should start and idle around maybe 600-800 rpm, turn on all your accessories, headlights heater/ac full blast idle will drop (engine may also die, if this happens go out and turn the idle screw 1/4 turn until the car starts and idles on its own).

4. adjust the idle screw on the throttle body until it idles around 600-800rpm, once it does turn off all accessories, turn off car.

5. plug the iacv back in and remove the jumper from the service plug.

6. start car, it should idle just fine.

if not then i would remove the idle screw and make sure its clean it can get some carbon build up on it and repeat the above procedure.

the idle set screw is on the throttle body on the top right side, if your looking at it from the passenger side its a flat head screw it may have a rubber cap on it.