Truck rides rough, kicks, jolts and blinking check engine light - Ranger-Forums - The Ultimate Ford Ranger Resource

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Old 08-12-2016
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Join Date: Aug 2016
Location: Boise,Id
Posts: 3
Icon5 Truck rides rough, kicks, jolts and blinking check engine light

I know I have a lot in the title so I write it all out as best I can. I'm just learning about how to fix my car and thus I don't know almost any of the abbreviations, acronyms or any sort of car talk I do apologize.

My 97 Ford Ranger Splash 4.0 V6 with 243,xxx miles, is having so many issues I don't even know where to begin. Most recently my truck has began to jolt, stutter, but it's only when I press on the accelerator and it is worse when the engine is cold. Finally, the check engine light will blink and go solid. I recently:
Replaced the fuel filter
Cleaned the MAF
Replaced the air filter

These have lessened the jolting, kicking problems but the still haven't gone away. What should I go for next?

I'm NOT taking it to a mechanic I've already put about $2,000+ into this guy so I am learning how to do it myself.

Thank you,
Stressed, Angered, Worried
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Old 08-12-2016
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Welcome to the forum

Good news is the 4.0l OHV engine you have is very very reliable even with higher miles

CEL(check engine light) will flash rapidly when there is a hard misfire that could cause engine damage, so that is bad and you need to let off the gas when that happens.
Solid CEL means computer has added a trouble code to its memory.
You NEED to get all the code numbers, which you can do at any auto parts store for free.
"I think code was................" is worse than no code at all.

Easiest thing to do is to pull out all the spark plugs and look at the tips, they can tell you what is happening inside the cylinder, keep them in order
Ford numbers cylinders this way
3 6
2 5
1 4

So 1, 2, 3 is passenger side, 4, 5, 6 is drivers side

Fuel injected engines can't use an idle screw, no jets, so they all use an IAC(idle air control) Valve.
Computer opens and closes this air passage(valve) to raise or lower the idle RPMs.

Never touch the gas pedal when starting a fuel injected engine.
Well, in honesty there is no "gas" pedal on any fuel injected vehicle, there is an "air" pedal, because that is all it controls, the amount of air that is allowed to enter the intake manifold.
On a Carburetor engine the " gas" pedal actually added gas to engine, not so with fuel injection.
The Computer is the only thing that can add fuel(gas).

So don't touch the "air" pedal while starting, lol.
When started, a cold engine should be idling above 1,100rpm, the colder the outside temp the higher the idle.
That's the computer seeing cold engine coolant with a sensor and responding by running a higher idle and richer fuel mix, like a Choke did on a carb.

It raises the idle using the IAC Valve, as engine warms up computer starts closing IAC valve to reduce RPMs
Target warm engine idle is 625rpm on manual, 750rpm on automatic

If your engine doesn't do this or after full warmed up the idle is higher than it should be you may have a vacuum leak.
After engine is warmed up and idling unplug the 2 wire connector on IAC Valve, it will close all the way.
RPMs should drop to 500 or engine may even stall, either is good it means no vacuum leak, if RPMs are above 700 then you have a vacuum leak.
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Old 08-16-2016
Thread Starter
Join Date: Aug 2016
Location: Boise,Id
Posts: 3
Okay I went to AutoZone today to have the codes pulled and they were:

P0171- System Too Lean (Bank 1)
P0102- MAF Circuit Low Input
P0301- Cylinder 1 Misfire Detected
P0304- Cylindar 4 Misfire Detected
P0174- System Too Lean (Bank 2)

Everything that has been suggested is the Intake Manifold Gasket has gone bad. How long will it take me to replace this guy? Should I set aside a full weekend (Fri-Sun)? I see that a replacement part will run me about $50.

Again Thank you,
Still Stressed and Worried
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Old 08-16-2016
Join Date: Jul 2016
Location: BC Canada
Posts: 955
Who suggested that it's your intake manifold gasket ?
Why not start with something less invasive like checking your spark plug wires/plugs.
What about you coil pack, or fuel pump not producing enough pressure.

If this my truck I would eliminate the simpler things from the equation before doing major engine surgery.

Get some starting fluid in a spray can and spray it around the intake manifold while the truck is running, if the idle increases a bit, then you have a vacuum leak.
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Old 08-17-2016
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Join Date: Aug 2016
Location: Boise,Id
Posts: 3
OK I went under the hood and there was one hose disconnected from the intake tube, and once I reconnected it the rough idle went away so I'm guessing that was part of the problem. Next, I followed RonD's instructions and disconnected the cable attached to the IAC. This dropped the RPMs WAY down, almost to the point of the stalling, but I don't know how low because my truck doesn't have a tachometer on the dash. I checked the coil pack and I was receiving a strong spark from all of the wire plugs. I can't check the spark plugs or the fuel pump until I go to someone with the tools.

It's getting better so again I thank you guys for all of the help. I'm learning a lot too.

A Little Relieved but Still Worried
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Old 08-17-2016
Join Date: Jul 2016
Location: BC Canada
Posts: 955
I'm still learning too, my B3000 is my first fuel injected vehicle.
It's not so bad really once you get to read the symptoms in relation to the codes what the computer throws out.
Ron said, very rarely are the sensors the problem, it's usually a bad connection on the plug to the sensor and/or a bad ground.

You need to get yourself an ohm meter, they're cheap and indispensable.
With that you can do simple continuity tests and check the resistance of your plugs and wires.
A simple visual check on your plugs goes a long though, they should be very clean looking.
That's a good sign that the idle fell when the IAC valve was disconnected, probably around 400 to 500 rpm. Defiantly that disconnected hose caused a major vacuum leak.

Here's an article on how to test the MAF sensor and it's various functions.

Read through the article a few times and get comfortable with it. Don't try and absorb it all at once.

My only caution is to be carful when testing any sensor, don't short anything out or accidently touch a live wire somewhere.
The key is to take your time and be by yourself and in quiet environment.

About your spark plug wires, once you have an ohm meter, the longest should have no more the 30,000 ohms or 30K ohms.
You can test for spark and it may have good spark, but under load and/or real world conditions, they won't work.

How old are your wires ?
Some wires have Kevlar in them, that stuff breaks down and the wires easily become "stretched" from handling.
The breaking down of the Kevlar causes the resistance to clime.

The reason why I mentioned your fuel pump is it would be causing a lean situation if it's not putting out enough pressure.
This is a grey area for me, but it would make sense and may cause the computer to throw up those codes.

Last edited by Jeff R 1; 08-17-2016 at 06:41 PM.
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Old 08-18-2016
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When you have both banks, 1 and 2, showing Lean then you have a vacuum leak in upper intake not lower, that would only show up on one bank, the side with the leak.

And since #1 and #4 cylinders were showing misfires, the two Front cylinders on each bank, then it could be a leak at the front bottom of upper intake, but maybe not.

Since you found a hose disconnected and engine ran better after reconnecting it, I think you found the problem.

And with the IAC Valve test it seems like no more vacuum leak.

The MAF sensor code was because of the vacuum leak.
MAF(mass air flow) sensor reports the amount of air coming into the engine, all the air.
When there is a vacuum leak then MAF sensor is not reporting ALL the air coming in.
When computer adds enough fuel for the "reported air" and it is burned in the cylinders the O2 sensors tell computer if the exhaust is Lean or Rich, if lean the computer will add more fuel until O2's tell it exhaust is correct.
Computer then looks at MAF sensor data and see it isn't reporting enough air to support the amount of fuel thats being added, sets a code to tell driver
P0102- MAF Circuit Low Input.

So it looks like all the codes were from one problem, vacuum leak.
I would drive it a few days and recheck if codes come back.

Last edited by RonD; 08-18-2016 at 12:59 PM.
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