Hello,
New user here to the site looking for some insight. My regular go to mechanic guy is busy so seeing if I can do this on my own?
I have 1999 Ford Ranger XLT V6 4,0. It is misfiring at idle and light and medium acceleration when taking off from a stop.
I have no check engine light.I used 2 different OBD2 scanners and no codes stored or pending showed up. The OBD2 scannersI used do not detect misfire. My mechanic told me 1999 Ford ranger rangers will not detect misfires. I had the sparks plugs and wires replaced recently. I double checked the spark plugs and they are working.
What would be my next step seeing as this is trial and error without a code?
Thank you

 

What is a misfire. Perhaps some kind of behaviors that lead you to believe it's a misfire? Engine stalled or not, restarted right up?
Something easy to check without your go to mechanic, check your MAF.
When you drive without a MAF (the ECU can't detect the present of MAF) the default air fuel trim ratio will be used.
Don't remove the sensor itself, just the electrical connector, start it up you will get thrown a code, just ignore, then drive as usual, if you feel major improvement then your MAF could be at fault, or just its electrical connector that needs cleaning, clean using electronic contact cleaner or 91% isopropyl alcohol. Whenever you plug the connector back the CEL should go away. Try first, then ask if you need more troubleshooting steps on MAF.

 

Thank you for the reply. Truck starts no problem. I had the fuel pump replaced recently which did go out. I disconnected the connector as you suggested. It's still riding rough when I'm at a stop. It will not stall. Still have no check engine light to give me a warning. I drove the truck for about 5min or so with the MAF disconnected.

 

Suggest you verify the spark plug wires are connected to the proper coil towers ,they DO NOT CONNECT as one would expect, ESPECIALLY NUMBERS 5 &6. WHICH ARE REVERSED.

 

Type in "Ford spark plug wire connections on coil". for 4.0 engine"

 

Thank you again for the reply. The spark connections are all correct.

 

Were you able to see AND trace the wires for cyls 5&6 and their location on the coil ?

 

 

Yes. The 5 an 6 wires are properly connected to the coil tower.