Idle questions

[Lpannell25]

so if you read any of my threads i have recently rebuilt the top end of my 2.9 on my b2....

when i come to stop light, sign, dead end.... any time i come to a stop lol the rpms dip down to about 500 and it acts like it wants to cut off after a little hesitation it goes back up and stays around 900-1000... is this normal or is my timing a little off or what do i need to check?
keep in mind im no mechanic more of a do it yourselfer and if you start talking about sensors and all that will have to explain where they are and how to check them and what not... thanks in advance

 

[06RangerXLT]

well your idle should be around 600-800. so 1000 is too high to begine with. I wish i could help more, but i dont know the 2.9 motors for sensors and what not. If it has it, an idle air control valve (top of the intake, 2 bolts and a plug) will need cleaning.

 

[infantry grunt]

i too am not oriented with that engine but pretty sure you timing wouldnt cause it to idle that irratically,maybe a vacuum leak possibly,get a can of brake parts cleaner and spray around your intake and hoses with the engine running,if your engine speed changes when sprayed in a paticular part etc. you have a leak there.good luck,hope this helps

 

[sjr53]

The 2.9L runs fine with a vacuum leak, just with a fast idle depending on the size of the leak. A dirty IAC valve can cause the hunting idle, but also a bad MAP sensor does cause at least a similar trouble. I don't know how idle would be affected by a bad ACT sensor by the IAC valve. I once drove to work & back twice with the TPS unplugged. It didn't idle well, but I don't recall the details other than it runs fairly well that way.