94 ranger

[fullmooner123]

I have 94 ranger with high idle of 1300pm and cant smog cause of it. I replaced the iac sensor but didnt help,the only thing that gets it to drop a little is pushing in the clutch.Can anyone tell me why it wont go down and why does the clutch have anything to do with it.

 

[bhawk]

Not sure what you mean by iac sensor. The idle air control or IAC, is a little motor that operates a pushrod that allows more or less air to get into the intake manifold. If you replaced your old IAC with a new one and got no change, then my bet is you have air getting into the intake manifold causing the engine to add more fuel, hence high idle. This is a common problem with rangers as upper intake to lower intake gasket can leak, ro vacuum hoses can split apart, allowing air, or most likely you have the lower intake manifold gasket leaking air. I fought a high idle on our 94 ranger for over a year before I finally bit the bullet and replaced the lower intake manifold gasket. Problem solved. Truck idles down to 650 rpm and runs so much better.
I suggest you pull your spark plugs to inspect them. If they are burning white, this confirms a lean burn or too much air getting into the combustion chamber.

 

[fullmooner123]

THANKS bhawk Ididnt know how to check,looking for white plugs.I just sprayed choke cleaner to see if engine would run faster.

 

[bhawk]

Spraying choke cleaner or the like around all vacuum hoses and connections to the upper intake is a good idea to find leaks there. However, the 4.0 engine is designed such that the joint between the head and the lower intake is UNDER the valve covers. Hence, spaying choke cleaner or propane or starting fluid, etc. won't get to that seam, and that seam is usually where they leak. That is why many rangers seems to use oil but you never see any blue smoke or leakage. Oil vapors from under the valve covers is seeping into the intake manifold because the seal has failed. So, if you are satisfied none of your vacuum hoses are leaking and the pipes where they connect to the upper intake are good and not leaking, and your plugs are whitish and not brown, I'd be changing that lower intake manifold gasket, and both valve cover gaskets, since both valve covers have to come off to remove the lower intake. Not a hard job, just takes time. I bought my gaskets at Rock Auto on the web, cheap and good parts. Not only did our ranger run better, fuel economy went up noticeably and less oil consumption after the gaskets were done.