'01 Ranger 4.0L Misfiring

tx_ranger · #1 (**permalink**) 11-07-2003, 10:29 PM

I recently bought a used '01 Ranger with the 4.0L engine. I believe that it is misfiring quite a bit after it warms up. I've got the following DTCs.

P0171 - Fuel Trim
P0174 - Fuel Trim
P0300 - Random Misfire

I know the P0171, P0174 are common, but does the P0300 point to something specific?

Thanks in advance.

SurfinScott · #2 (**permalink**) 11-09-2003, 10:39 PM

It could simply be that you need new plug wires. If the ones on there are old, or you dont know cause you just bought it, buy a new set and see if the problem is solved. I had the same deal when I bought my 93 ranger. Got new wires and it ran great. if not, it could be old plugs, or maybe something bigger. good luck.

tx_ranger · #3 (**permalink**) 12-13-2003, 11:03 AM

Update:

A hose to the PCV valve had a crack in it. I replaced it, reset the check engine light and that problem was solved.

I had other issues with rough idling and skipping. This was caused by excessive carbon buildup. It knocked out the MAF sensor. I had the engine "decarbonized" at the dealership and replaced the MAF sensor. Now it runs as smooth as ever. Gas mileage is better too.

FYI, I tried the DIY tricks of cleaning the MAF sensor and engine cleaning fuel additives. They did not work in my case.