surging at idle

[rangerrager]

so guys my truck is surging at idle not too high but it surges.sometimes the idle will go down real low and almost stall .what could cause.i replaced the maf yesterday it didnt make a big diffrence.what else could it be?

 

[Power Ranger 1]

Mine Does The same thing and i have replaced every sensor and every thing you could replace but the PCM can someone help us PLEASE!!!!!!!

 

[rangerrager]

and i smoked tested mine found a small vaccum leak and fixed it and the problem is still there.

 

[Power Ranger 1]

I guess no one now what it could be or dont want to help us out i have tried too get some help on here and cant i guess i am too new to this site or something not sure well if you find out what it is please tell me and i will do the same thanks

 

[rangerrager]

yeah ,i have done the same.i will pm you if i find out whats wrong with it.
thanks
ryan

 

[Power Ranger 1]

Mine is now running like cap around 2000 to 2500 but if you mat the gas WOT it runs Like a Beast

 

[rangerrager]

yeah dude same here. it hesitates just a little when you take floor it then it takes off and gets up and goes

 

[turbo cat]

surging is a very lean idle. most likely a fuel problem or vaccum leak.....

 

[Power Ranger 1]

Thanks But that is all i amgetting from people on here is a vac leak i have replaced every vac hose , vac cap , every gasket , every sensor , every injector, and both 02s and i still have the same problem so thanks for your help

 

[rangerrager]

i smoke tested my engine..no leaks wich in turn means NO vaccum leaks..the problem must lie within something else..how about injectors or fuel pressure regulator

 

[Power Ranger 1]

I Replaced the injectors still nothing just replaced the Ignition Module and didnt help it one bit i am fixing to put a damn 347 stroker motor it it so i guess i want to keep the 4.0 i like out running the mustangs in it

 

[rangerrager]

so all that is left is the fuel pressure regulator ..that has to be it..

 

[Power Ranger 1]

Yeah And The PCM

 

[Power Ranger 1]

Why is That when i unplug the 02 sensors the truck runs DAMN GOOD can anyone help me out here

 

[mht95ranger]

How does one smoke test an engine? I have a crappy running 4.0l as well and think it is a vacuum leak.

Thanks David