Fast Idle RPM?

[Puslinch]

What should the fast idle speed be for a 90 GW? Truck in Neutral, engine cold. 1000RPM?
lower?, higher?

[Cecil14]

Should be a sticker somewhere under the hood that gives all the specs. Like I said, SHOULD be there, doesn't mean it WILL be there. It should be higher than that though, like somewhere around 1750-1800 I think.
Don't have a book right here so I'm not sure on the exact number.


Anthony

[Veepster]

the idle is usually set with vehicle in drive and foot on brake

[SpruceMoose]

i think the projection manual calls for 1200 rpm, but i have mine set for about 1000, in gear. when it warms up it idles at 600 in gear, 800 in neutral.

[J20fan]

My J20 sticker calls for 800 + - 100 Neutral 1600 high idle. My Wag calls for 600 Drive 1600 High Idle. I found that a bit high so I have dropped it to 1100 because of the very cold startups we experience here. I run synthetic oil but I do not like to run the engine that high while cold. I cannot make out part of the diagram but I believe the A\C solenoid spec is there. Maybe someone else can give you that info.

[Chero77]

The factory specs for fast idle are all around 1600 rpm regardless of year. AMC specified a high number to get the engine to warm up quickly for emissions reasons. As a practical matter you probably don't need to idle that fast.

Here in warm So. Cal. my engine starts and warms up fine with a high idle of 900 rpm (in nuetral). I suspect that you may need a faster high idle in cold climates.
I run a slow idle of 600 rpm (again in nuetral). However, with an idle speed that low you need to shift into nuetral when you come to a stop or the engine will bog. My daily driver is a manual, so popping into nuetral and coasting to lights is a routine habit for me.

Also, slow idles probably save a little on gas and if your drivetrain bangs when shifting into reverse ( a common problem on these old trucks) the slow idle makes this a lot less noticable.