1500 + idle

[MegaSuiter]

Just bought 256!...Or 265? The Guy wasn't sure. He had a big 16g, 550cc injectors, and a 190lph fuel pump on it. I was wondering without tune if it was normal to have that high of an idle oroukd I be looking for boost leaks or the throttle body?
Thanks... /ubbthreads/images/graemlins/cool.gif

 

[FlyingEagle]

Full cold, that idle is fine. When started cold it will rise up to almost 2000 RPM, drop to 1500 RPM and settle down in small increments as it warms up, but should land you at 800-850 RPM. IF your engine stays hovering at 1500 RPM then yes you have leakage, or a throttle cable that is too tight. Sounds like the throttle system needs a going over.

 

[MegaSuiter]

Goes to 2000 and stays there until warm, then to 1500-1700, and sometimes at a red light it will drop to 1000 and then raise right back up to 1500-1700. Is there a tightening/loosening setting on the throttle body? Or could it be an ISC problem?

 

[FlyingEagle]

Have you checked the VFAQ or checked the factory manual for setting idle and timing? Did the previous owner have this problem too?

 

[MegaSuiter]

He said that it's normally the ISC that makes it idle that high.

 

[FlyingEagle]

If the ISC is out of control, you can test the ISC by checking the resistances.
I cannot think of how that would work if there was excessive resistance on those coils/terminals,
but a short in the coils will take out the ISC drivers on the ECU.

Check to make sure you have a little slack in the throttle cable wire with no one pressing on
the gas pedal. Next check to make sure the throttle plate closes fully, and that the Idle Stop Swith
is not too far out. These are some of the basic, outside of the system checks, that you can do.

 

[MegaSuiter]

The ground to my idle switch was unplugged... I plugged it in and the engine started hunting... do I need an idle switch then?

 

[FlyingEagle]

Check the VFAQ and see idle surge/hunting and how to set your ISC/base RPM.
If setting the ISC into the proper range (really helps to have a timing light and or a datalogger) does not help you set things right, you may have a vacuum leak somewhere.
The best and most basic thing to do is read the VFAQ about idle settings and how to set them.
Do you happen to have the idle screw (BISS screw) in place? Is the rubber cap in place over it?

 

[MegaSuiter]

the rubber cap is off and it looks like the screw is pretty crusty. Should be going over everything tomorrow when I can actually work in a nice warm garage!

 

[gramkrakr89]

Quoting FlyingEagle:
Check to make sure you have a little slack in the throttle cable wire with no one pressing on
the gas pedal. Next check to make sure the throttle plate closes fully, and that the Idle Stop Switch
is not too far out. These are some of the basic, outside of the system checks, that you can do.



These are words of wisdom - first things you should check when chasing an idle problem! Keep them in mind when working.

 

[MegaSuiter]

Is there supposed to be slack side to side on the throttle plate?

 

[SouthCaliVR4]

the rod may slide back & forth in the bushings just a tad if the plate to bore clearances aren't perfect or if you have the blade wide open more of issue would be play at the bushings to the throttle bar or big leaks at the throttle body seals.

 

[MegaSuiter]

I haven't gotten to a garage or a ohmmeter, but i did unscrew the idle switch half a turn with the ground plugged it and it idled at like 2000...I screwed it back in half a turn and it started to hunt again after a couple minutes. Does this say anything?

 

[MegaSuiter]

When I turn the key the key and don't have the clutch in is the ISC supposed to make a click sound?

 

[beaner]

The MPI relay will click.

Did you try what I suggested in your other thread?

 

[MegaSuiter]

Nope. Just tinkering with it every other day. I will get around to using all of the advise on here.

 

[MegaSuiter]

Also the two nipples that come off the EGR valve on the pic you posted on my other thread...Is it okay if those aren't blocked and nothing leads to them. I mean they are just sitting there. I don't feel any vacuum from them, but just curious.

 

[vtecds1]

Quoting MegaSuiter:
When I turn the key the key and don't have the clutch in is the ISC supposed to make a click sound?



Iirc...the isc will click as soon as theres power to it.

 

[MegaSuiter]

Is it bad for it not to vibrate? I thought it was supposed to vibrate because the motor moves the valve...

 

[vtecds1]

Its suppose to vibrate. I know you might have not have any time right now, but follow vfaq on how to test it just to make sure its not bad.