2002 Ford Ranger Emissions/Fuel/Sensors

LEABEA1

MEMBER
2002 FORD RANGER
6 CYL
2WD
AUTOMATIC
150,000 MILES

About thirty minutes into my daily commute home, the vehicle started loosing power, no matter how hard I hit the accelerator the truck would not go over 50mph or 3100 rpm. When the truck is in park it wouldn't rev past 3100 rpm. Put in a bottle of B-12. Ran good for 3 weeks. Happened again about 30 minutes into drive home, stopped put in three gallon of gas, which put me to over 1/4 tank, ran good for 10 more minutes. Limped home at 45mph. We have changed the MAF sensor, fuel filter and checked vacuum lines. Codes given said fuel mixture to lean.
PO171, PO174, Misfire on Cylinders 5 & 6. Any ideas what it could be? My next move is to check EGR valve or is this a waste of time?

8 Replies

SERVICE WRITER

MECHANIC
9,123 POSTS

Them first two are lean codes, use some carb cleaner and spray around the intake manifold to see if there are any leaks. The idle will change when it sucks in the fluid.

Are all of the codes current?

SPONSORED LINKS

Was this

answer

helpful?

Yes

Thursday, April 17th, 2008 AT 3:35 PM

MERLIN2021

MECHANIC
17,250 POSTS

The V6's with plastic manifold can develop a vacuum leak at the seams get a can of spray gumout, spray the vac lines and maniflod area, when the idle changes, youve found the leak! You want the engine running and spray on the outside but do direct the stream onto the hoses, if it is a vacuum leak, the engine idle will change speed, then you have detected a leak, repair the vacuum leak and see how it runs!

That will take care of the 171 and 174 the 176 and 177 are the fuel composition circuit. Maybe some bad gas, or a problem in the sensor or wiring.

Was this

answer

helpful?

Yes

Thursday, April 17th, 2008 AT 3:38 PM

LEABEA1

MEMBER
4 POSTS

Codes 176 and 177 showed up before MAF was switched. Waiting to see if the truck has the same problem today on his ride home. Will post any other codes if the truck malfunctions again.

Was this

answer

helpful?

Yes

Thursday, April 17th, 2008 AT 3:49 PM

MERLIN2021

MECHANIC
17,250 POSTS

Can you clear the codes? Do that then start again!

Was this

answer

helpful?

Yes

Thursday, April 17th, 2008 AT 4:40 PM

LEABEA1

MEMBER
4 POSTS

Okay, here is the saga continued.
All codes cleared. Have changed the Throttle Positioning Sensor, MAF, Spark Plugs & wires. The truck still acts like it always has. 35 minutes into the drive going along at 70mph, engine stumbles, drops down to 20 mph. If you try to floor the accelerator truck will die. You have to keep a steady low pressure on the gas pedal, until you get back up to 50mph. WHAT CAN CAUSE THIS! Truck will be fine after you turn off for an hour and then after warming up again for about 30 minutes it starts all over. HELP. No codes showing when this happens.