P0171 & P0174 Problem

[Steve'99]

So here's the details:
1999 Ford Explorer 4x4 V6 OHV 148,000 Miles
Oil changes every 3000 w/ synthetic oil; well taken care of truck
K&N Air Filter about 40,000 miles ago; never been cleaned, soon,
not that dirty. Fuel filter about 30,000 miles ago
Oxygen sensors, plugs and wires last weekend
Mass air flow sensor last monday
P0171 & P0174 came back on today

About seven thousand miles ago my check engine light came on, so I
bought an OBDII code reader. Came up with P0171 & P0174. Bank 1 and 2 lean. I decided to find the problem myself because of the prices a shop would charge are to high. Several different AutoZones, Checkers and PepBoys told me it was the oxygen sensors setting off the check engine light, and to not be concerned that my engine was running lean; It would compesate by itself for the lean condition. I waited quite a while to change the oxygen sensors, but when I did change them and reset the codes, the light came on about 50 miles later. I searched the net and found this site, and many other sites about "contaminated mass air flow sensors." I changed that on monday, but the light came back on today. Any suggestions on what I might check next?

 

[spindlecone]

Intake gaskets, Vac leaks perhaps

 

[jp450]

With the OHV I would doubt that it is the intake gaskets. I would look for vac leaks. Make sure that all hoses are attached securley and that none of them have any dry rot. There is a vacume tree on the OHV that tends to cause problems. ie broken connectors and lines that fall off. It is on the right side of the engine towards the back. Should be accessable from the top of the engine.

Has anyone here seen the trend with the big parts places... Check engine light = O2 sensors. Is that what they are trained to say? They should be ashamed of themselfs to even suggest that it is the O2 sensors unless they have done a through inspection of the vehicle.

 

[Skibug]

Has anyone here seen the trend with the big parts places... Check engine light = O2 sensors. Is that what they are trained to say? They should be ashamed of themselfs to even suggest that it is the O2 sensors unless they have done a through inspection of the vehicle.

Yep, what they don't seem to realize is that even if a O2 sensor is bad, it is usually the result of some other problem actually causing the sensor to go bad.


I would also check fuel pressure etc... along with any possible vac leaks. Have you noticed any rough idle or any abnormal driving issues?

 

[Steve'99]

no driveability issues besides lacking power a bit, idle could be better but its not noticable to anyone but me.

 

[Larry2010]

if it's rough running cold and smoothes out after it warms up the intake o-ring gaskets are a good bet BUT those usually throw up a code while it's cold.

 

[Chris1973]

So here's the details:
1999 Ford Explorer 4x4 V6 OHV 148,000 Miles
Oil changes every 3000 w/ synthetic oil; well taken care of truck
K&N Air Filter about 40,000 miles ago; never been cleaned, soon,
not that dirty. Fuel filter about 30,000 miles ago
Oxygen sensors, plugs and wires last weekend
Mass air flow sensor last monday
P0171 & P0174 came back on today

About seven thousand miles ago my check engine light came on, so I
bought an OBDII code reader. Came up with P0171 & P0174. Bank 1 and 2 lean. I decided to find the problem myself because of the prices a shop would charge are to high. Several different AutoZones, Checkers and PepBoys told me it was the oxygen sensors setting off the check engine light, and to not be concerned that my engine was running lean; It would compesate by itself for the lean condition. I waited quite a while to change the oxygen sensors, but when I did change them and reset the codes, the light came on about 50 miles later. I searched the net and found this site, and many other sites about "contaminated mass air flow sensors." I changed that on monday, but the light came back on today. Any suggestions on what I might check next?

Had the same problem earlier this year.was the camshaft position sensor.i changed that and the map sensor and crankshaft position sensor because why not and they are all connected to those codes.

 

[410Fortune]

there is no map sensor on a 2000 OHV

171 and 174 are almost ALWAYS intake gasket O rings, yes the plastic intake OHV from 95-2000 have O rings for the intake and they leak and let air in, as does the large EGR O ring......they should all be replaced

 

[Chris1973]

there is no map sensor on a 2000 OHV

171 and 174 are almost ALWAYS intake gasket O rings, yes the plastic intake OHV from 95-2000 have O rings for the intake and they leak and let air in, as does the large EGR O ring......they should all be replaced

Thanks

there is no map sensor on a 2000 OHV

171 and 174 are almost ALWAYS intake gasket O rings, yes the plastic intake OHV from 95-2000 have O rings for the intake and they leak and let air in, as does the large EGR O ring......they should all be replaced