running like it has a cam

[okietheranger]

after i installed my 4.0 in my 85 ranger it some what has problem, sometimes in the cold or if i just havent started it in a while it will crank and crank and crank.. so then when the beast comes to life it will run pretty ok but if i try to hold the throttle stedy the rpms surges and at idle it will kinda spit and suptter like it has a huge cam in it.. i replaced the o2 just think maybe its running way way rich which it is ( cause of my eyes buring like crazy from exhaust ) so the only other thing i can think of is i switch out the oil pressure sensor for a mechanical also switch the coolant switch for a mechanical.. i left the other sensor in the houseing i belive was for the computer not the gauge.. anywho im pretty stumped at why it does this maybe the air temp sensor in the upper plentum?

 

[mhughes165]

i dont recall but does the 4.0 utilize a map sensor, i know when the older ones run like they have a viscous cam it is often the culprit

 

[okietheranger]

yeah i dont belive it has a map sensor that would of been my first questonable sensor.. it does not have a cam just idles and such like it does.. other than that what else could cause that? im all open for any sugestions!

 

[BlackBII]

I'm assuming it ran fine when pulled?

 

[okietheranger]

yes it ran fine.. i got it from my sister who wrecked the explorer.. so than i got it after she wrecked it.. everything is hooked up right the only thing i changed was the electric sending units on the oil pressure and the water changed them to mechanical

 

[canyoncritter]

the computer need's the temp sensor so it know's to go to closed loop.


4.0L are MAF=mas airflow

 

[okietheranger]

right but isnt there two sensors? one for the temp sensor its self and one for the computer? my thermostat houseing has 2 sensors in it.. correct me if im wrong

 

[pineypower1186]

just for future reference if the exhaust burns ur eyes, its running super lean.

 

[Hahnsb2]

right but isnt there two sensors? one for the temp sensor its self and one for the computer? my thermostat houseing has 2 sensors in it.. correct me if im wrong

Yes that is correct. It sounds like a vacuum leak to me...

 

[92MiniMonster]

On the back of the plenum on the drivers side, the vacuum tube that goes straight out of the side to the, brake booster? is it? Did either end of that come off or does it have a hole in it, my brothers 4.0 runs like it has a nasty cam in it if that hose pops off. Just though id put my 2 cents in.