98 ranger 4.0 mis poor performance

BigVWman · #1 (**permalink**) 11-14-2006, 01:25 PM

Hello, i was hoping someone may have some insight here. I tried search and then found server message so i'm looking for help. I have a large mis multiple cyl especially on accel and uphill. I was only getting codes 171 and 174 right left banks lean. I have 129+ miles. already did vacuum lines to the dpfe last time i had an issue. i have cleaned the iac and maf last fall as well as changed plugs with autolite dp's. This problem just started on sun driving back from fl going through VA mountains. it was bucking uphill to the point that i called and warned a buddy he may need to come get me. Then cleared up a little in ohio after the mountains so i started to think temp sensors or something. however after i returned to mi the problem returned. i was thinking it felt like injector or plugs but i'm lost on this one.

fplorer · #2 (**permalink**) 11-16-2006, 05:09 PM

Sounds like you might have a fuel pump that is going bad. Do you have a way to check your fuel pressure while driving?

BigVWman · #3 (**permalink**) 11-19-2006, 01:56 PM

no way to check pressure while driving but if it was a fuel pump or pump pressure problem wouldn't it get worse if open the throttle further. When its missing i can give it more throttle and the othe rcylinders still seem to pick up the pace.

fplorer · #4 (**permalink**) 11-20-2006, 10:44 AM

I had a fuel pump go out on my explorer and it acted the way you are describing. I had the same codes you have and I couldnt figure out what was wrong. It had the codes for about a month before the symptoms showed up on a trip. I pulled off the Interstate and it died at the stoplight. Would start and barely run. It would pick up and go and the higher the RPM the better it would run. It would run ok for a while, then it would act up. When the tank was full it would be ok. When the pump would start to heat up it would start stumbling again. I changed the pump in the parking lot of an Auto Zone on a Sat. night in San Antonio Tx. 300 miles from home. (not much fun by the way) All problems went away.