Idle rpm

[madog7200]

At what rpm does y'alls trucks idle... I've got this new motor in and now it is idling at about 1500 which I know is too high and I can't figure out why..

 

We started by fixing the exhaust leak caused by the new manifold being bent and not sitting flush with the block, and I've replaced all of the vacuum lines thinking it was getting too much air...

 

Now I'm at a stand still

 

It's a 91 4.0 4wd

 

Thanks in advance guys

 

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[SBpunk]

Auto or Manual? Autos tend to idle a bit higher if I remember correctly. I'm at about 750rpm. Check your sensors, vacuum, clean your throttle body etc. I got a water bottle and sprayed water around the vacuum spots until I found leaks. The one going to the MAP sensor on the back of the motor (flat gray piece) has a small tube that likes to break. 

[madog7200]

Auto or Manual? Autos tend to idle a bit higher if I remember correctly. I'm at about 750rpm. Check your sensors, vacuum, clean your throttle body etc. I got a water bottle and sprayed water around the vacuum spots until I found leaks. The one going to the MAP sensor on the back of the motor (flat gray piece) has a small tube that likes to break.

It's a 5 speed, the throttle body and was cleaned thoroughly when we swapped motors.

 

And I replaced the vacuum line going from the map to the intake manifold

 

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[Eagle]

700 to 750 is correct.

[madog7200]

700 to 750 is correct.

That's what I thought, I'm beginning to wonder if the fact that I used bigger diameter hose as vacuum line is the problem?

 

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[Ωhm]

OD doesn't matter, larger ID technically could slow down response time, but at a steady state (ex:idle) will have no bearing at all.