Hi Guys,
I'm new to this forum. My pastor has a 1996 Ranger Splash with the 4.0EFI motor. He has been having a misfire for over a year, spent >$500 in repairs. He has had it to 2 different repair shops (neither of which were Ford) and also a For dealership. I'm hoping you can point me in a direction.

The misfire problem beganwith cylinder #2. After some time it also began in cylinder #4, after more time it began occuring alsoin cylinder #1 & #3. So now it occurs randomly in cyliners #1, #2, #3, #4. To date there has never been and issue withcylinder #5 or #6.

He has had it Advance auto several times to have the codes check. Each time it will give a specific cyclinder number. He replaces the spark plugs and it will run better for a week or so then start again.

Todate he has had the following replaced: spark plugs, wires, oxygen sensor (twice), temperature coolant sensor and EGR sensor.

Personally I don't think the oxygen sensor, temp sensor or EGR sensor have anything to do with his issue.

When the spark plugs are pulled on the cylinder that is misfiring they look gray but have the appearance they have been hot. They do not look rich.

Initially I was thinking crank sensor but then realized that is external and looks in good shape. Then I thought perhaps fuel filter or low fuel pressure. I would think all 3 of this would apply to all 6 cylinders.

Could the coil pack have a turn to turnshort on the 4 cylinders he's having trouble with? I'm uncertain if there is a coil for each cylinder within the coil pack?

Any help or direction is greatly appreciated.

 

Gently wipe clean the crank sensor. Have you changed basic things like air and fuel filters? When was your last oil change or check?

 

My understanding is that all basic items have been addressed. Repeated oil changes, fuel filter changes, and the injectors were removed and cleaned. The only thing that has not been done is replace or wipe the crank sensor, replace the coil packs.

 

You said the plugs look like they were running hot.Arethe plugs the correct heatrange for the motor?

 

My understanding is they are not Ford brand name but are the correct part cross referenced to another brand. The spark plugs on the cylinders that throw a code are changed every few months. I do not know if he has changed brands each time.

 

I found one in the trash. They are Autolite 765. I'll have to check with Advace Auto to see if they are actually the correct plug. I'd guess they are.

 

Spark plugs should always be replaced as a full set. Also you should match them up to the originals ones to be sure there's no major difference. Also be sure to check the gap when installing (even if "pre-gapped").

 

There are only a couple ol methods commonly used lor tracing a misfire to a specific cylinder: The first time that it happened to I thought it was my Merkur oxygen sensor... Any way, OBD II misfire counters and misfire codes. Most niannlacturers use a method of measuring crankshaft acceleration to determine if a particular cylinder is misfiring. The problem is that crankshaft acceleration depends on torque. Would it surprise von to know that a misfire code will almost never set at idle or low load because torque is very low under these conditions? Following arc the EPA regulations concerning types of misfires and the requirements for setting a Malfunction Indicator Light: Type A is a catalyst-damaging mislire, which will cause the MIL, to Hash (onetrip code). Type B is a misfire that will cause an emissions failure but not damage the catalyst (two-trip code).