Help! Just bought a 97 4x2 4.0 5-speed Ranger with only 9,000 miles. Truck has a very rough idle, almost like a mild cam were in it.

Sometimes the whole truck vibrates heavily while at an idle. Oh, no tach in it.

Going through the gears - 1st, 2nd, and a little in third - there is a smaller, different feeling\sounding vibration. Once you get the RPM's up it smooths out.

Also, for a 4.0, it is kind of a pig. It doesn't have the pick up you would expect.

When I'm cruising at 65mph, you can feel these short hesitations like you would feel if the a\c was running.

Truck sat for a bit, maybe fouled injectors??? What do you think???

Thanks,
JOhn

 

Welcome to FTE John.

What's your definition of "sat for a bit"????

So many possibilities.
In round numbers that vehicle has been driven about 2.5 miles a day, not enough to even get the oil warmed up.

Could be gumed up injectors.

How old is the gas in the tank & the oil in the crankcase????

Have you done any scheduled maintenance, like replacing filters & fluids, checking spark plug insulators & ignition wire boots inside, for dirt or cracks & lubing them inside, with a good dielectric grease, to help prevent flash over on these damp morning starts????

 

I agree, just because the engine only has 9K on it doesn't mean it doesn't need a little TLC. At least pull the spark plugs and look them over. Replace if necessary. Change the air and fuel filters. I would also clean the MAF sensor. You might also try running some fuel injection cleaner through the system.

 

Thank you both for replying. The gas, oil, plugs, air and fuel filter are fresh. I put two containers of Lucas injector cleaner in with two tanks of "Super" unleaded. I bought an 8mm Bosche wire set tonight.

How do you clean the mass airflow sensor?

I was told the injectors could be fouled. How do I determine if they need replacing?

Thanks for the help.

John

 

My goodness John, slow down & take a deep breath.

So why did you decide to replace the plugs & plug wires???? Did the wires test out of tolerance for resistance, or were they damaged??? How did the old plugs look????

Our engine with te "waste spark" system needs double platinum replcement plugs, so did you replace them with Motorcraft or Autolite double platinum plugs???? If not, you may have drive ability problems. Other plugs like Bosch, don't seem to hold up well in Fords "waste spark" system & soon cause problems.

If the wires resistance checked within spec, & they're not damged they're likely ok. I don't know about Bosch wires, most here like & have fewer poblems with Motorcraft or Autolite, who makes Motorcraft wires & plugs.
So also keep this in the back of your mind, while chasing your problem.

If the air filter was clean & fit well in the air box & you don't have any computer trouble codes, the MAF is likely ok imo.

If your bound & determined to clean it anyway, there is a thread in the "Tech Info" thread atop this forum, that'll explain how to do it. But why fix what ant broke?????

Just be careful, remove it & let it cool completely & don't touch the small wires, use a O2 safe "throttle body" spray cleaner & spray gently.

Also loads of other good info there.

Good idea to replace the fluids & filters you've done so far imo.
You might check the air tube between the filter box & fender, to make sure nothing has built a nest in there & starving the engine for air!!!! lol

I'd maybe pull the pcv valve & make sure it's working ok & is clean.

I'd also look to the coolant & at least test it's acidity, if it's still the OEM stuff, it likely needs changing & the system flushed. While your at it, remove the upper radiator hose, squeeze it while lookng for micro cracks in the inner tubes surface. If you see any micro cracks, replace ALL the coolant system rubber hoses, including the heater & coolant recovery tank hoses.

Think I'd change the tranny & differential & power steering fluids too, seeing as how they're coming on 10 years of age & who knows how the vehicle has been stored all these years.

I know none of this has to do with how the engine is running, just some more thoughts.

On the injectors, you might do a fuel pressure test, to see if the pump & regulator are providing enough pressure, then maybe to a flow test, to see if pump volume is up to spec.

If so & by then you've gone through two tanks of treated gas & things aren't better, I'd pull the spark plugs for a reading, if you didn't do it on the old plugs, as Rockledge suggested, so you can get a feeling for whats going on in there.

If you still suspect the injectors, try runnng a stronger detergent pressure cleaning system through them, that hooks up to the fuel rail & see how that does.

If your of a mind to have the injectors tested, then pull them & have them cleaned & tested at a good shop, known for it's fuel injector work.

On the premium gas thing, our engines are set up & timed to use regular gas & the factory doesn't recommend using premium gas, as it might cause driveability problems.

Premium has a slower flame front, so it's kinda like retarding the spark, to use it in our engines. It can also cause excessive deposits, bacause of this, so I think I'd just use regular, while trouble shooting your driveability problem.

My 99 4.0L Ranger & 94 3.8L Taurus both like Chevron or Chevron Texaco gasolines. These petrols have solved some driveability, engine deposit & fuel consumption problems for me, so keep them in the back of your mind, in case you think gas may be part of your problem.
Chevrons "Techron Concentrate Plus" in a tank of either of those gasolines, makes a good cleaner upper imo!!!!!

Let us know how it goes.

 

Thanks for the reply.

Yes, the plugs are the OEM ones. No difference in rough idle after changing.

I haven't put the wires on yet. I figured that would be one failr cheap thing to eliminate. How do I check the spec. on them? Theu look fine. I bought the 8mm becuase the stock ones were 7mm and I figured I might get a little more juice in addition to eliminating the wires froim the equation.

"If the air filter was clean & fit well in the air box & you don't have any computer trouble codes, the MAF is likely ok imo."
There was debris from a mouse nest in the airbox. No codes though.

"I know none of this has to do with how the engine is running, just some more thoughts." Thank you. I appreciate any advice.

It's a 5-speed. How do I change the fluid on the tranny?

"On the premium gas thing, our engines are set up & timed to use regular gas & the factory doesn't recommend using premium gas, as it might cause driveability problems."
Wow, were getting boned even more than I thought by the oil companies!!!

"...in case you think gas may be part of your problem." I drive alot so I use many different fuels. However, I will make it a point to try Chevron and Tex.

What is "imo"?

Thanks so much for your time.

John

 

IMO = In My Opinion.

No we aren't being boned by the oil companies, it's just that our engines are set up, tuned & timed to run best on regular fuel.

High compression engines need higher octane, slower burning fuel, to work best & keep detonation down, so they won't self destruct.

If we run a slower burning fuel in our lower compression engines that are timed closer to top dead center of the pistons compression stroke, the exhaust valve will begin opening on the power stroke, while the fuel is still burning & we'll loose some performance, cook the exhaust valve & seat, leave unburned fuel around to cause deposits & over work the cat converter, so premium fuel in an engine not designed for it is a waste of money in more ways than one!!!!!

You can test your old & new wires with a multimeter, set on the ohms scale.

If you decide to use the new Bosch wires, test them anyway, just because their new, doesn't automatically make them good, I've seen bad parts,right out of the box!!!!

Measure the wires internal resistance, end to end. It should be about 1,000 ohms per inch of length, 30,000 ohms max, reagardless of length.
If the OEM wires test good, I'd use them, return the Bosch set & use that money for something you really need.

Seeing as how you found mouse debris n the air box, I'd take the air tube between the fender & air box loose & make sure the intake air tube & the area under the inner fender isn't restricted with out of sight debris!!!!

Look in your owners manual for your tranny drain location & lube type.
My 99 owners manual shows the fill & drain to be on the drivers side of the tranny & Mercon as the manual tranny lube, but it may have been different for your 97, so check it out in your owners manual.

If you don't have a repair manual or CD I'd invest in one, if you plan to turn your own wrenches, I have repair manuals for all my rides.

If you don't have a owners manual, you can download one from the "My Ford" or Motorcraft web sites.