I have a 1992 Ranger with a 3.0 v6 engine automatic that starts hard most of the time and idles so rough it shakes the whole truck. I have to keep my foot on the gas slightly to keep the engine running. If I let it stall out it is hard to start.
I have replaced the fuel filter and spark plugs.
The spark plug wires, points etc. are all original.
The truck has 79,000 miles on it.

 

Why dont you finish up the tune up with new wires/ and air filter?

BTW, I dont think your truck has points. Those were replaced years ago.

 

Welcome to FET!!!

I agree, replace the rest of the stuff for the tune up, then test fuel presure and codes.

How does it run when warmed up?

 

I Just Bought A 92 Ford Ranger From A Friend. I Have The Same Problem With The Rough Idle. I Have Done A Complete Tune Up, Down To The Pcv Valve. It Does Not Cut Off When Idling And Never Did, But The Tune Up Did Not Help. Does Anyone Know Anything Else I Could Try. I Checked The Fire Order And Everything Was Ok. The Engine Runs Great, But Does Not Idle Well. Help? Ps Yes It Has Points And Rotor

 

I say check the fuel pressure, that could cause the idle stalling, very rough idle, and then working ok at more than idle.

 

After checking FP and for the presence of codes, I'd be looking for a vac leak. Any chance the exhaust is black when it's idling rough? No codes or a rich code and black smoke would have me thinking about the FP regulator.

 

Is checking the FP I can do or something I need to have a shop do? Another thing, could the timing be off on the engine or is this engine too new?

 

Checking the FP is easy, you can do it. Timing could be off, but I doubt it, start simple and we'll work our way through the problems.

You'll need a fuel pressure gauge, you can get one from your local auto parts store, just attach it to the air-valve looking thing on the fuel rail, and turn the key to RUN, check pressure, make sure it holds, start the engine and watch the pressure, rev it a little bit and see what happens.
Report back with your results.

 

smoke eater,

My 91 ranger with a 3.0 has a rotor, but there are NO points. If you have points in your 92 distributor, you will need to set the points to the proper gap with either a feeler gauge or a dwell meter. But points and condensers in the distributor were eliminated 30 plus years ago with electronic ignition systems. So i think its safe to say that your 92 does not have any points, so long as this is the original engine.

Have you cleaned your throttle body or MAF sensor? These could cause rough or poor idleling. Your engine is not too new for the timing to be off. You'll need a timing light to check. Have you replaced the distributor cap? Your IAC could be dirty or need replacing. Look for vacuum leaks. Fuel injectors could be dirty too! Good luck.

 

retreat,

Sounds like you may have a large scale vacuum leak. Make sure your PCV is fully seated into the valve cover.

 

PCV should be on the far back of the driver's side valve cover.

 

Thanks I will try all these things and get back. Someone else told me to try cleaning the throttle body.

 

i have the same problem with my 99 4.0 but everycopule of days it will idle fine but then will start cuting off again any suggestions on whats wrong

 

Since your truck is a lot newer you should start a new thread for your problem.

 

Smoke Eater, how'd it go?