[updated:LAST EDITED ON 22-Oct-02 AT 07:48 PM (EST)]My 1997 F150, 4.2 V6 with 97,000 miles has a check engine light on. Codes returned are P0171 and P0174 Bank 1&2 fuel mixture lean. Also I/M shows Evap System Not Ready, but does not return any codes. I have checked all of the normal sensors, VMV, MAF,Fuel pressure, etc and all seems to be in order. If I erase the codes the light will return after about three start cycles. Any help would be appreciated.

 

As far as the fuel mixture lean condition. Have you changed your air filter? My light was coming on and when I cleaned my air filter the light and code quit.

 

[updated:LAST EDITED ON 24-Oct-02 AT 10:00 AM (EST)]Hi Dan,

Thanks for the comments. I recently changed my air filter and fuel filter. It seems there is a long list of problems that can set the P0171 & P0174 codes. I am glad that yours seem to have had a simple solution.

Thanks:

 

I have a '98 Expedition 5.4L w/67k miles....I'm currently trying to figure out how to eliminate the P0171 and P0174 codes.....

I changed the fuel filter, cleaned the K&N air cleaner, changed the pcv valve, pulled off and checked every vacuum line,check for loose bolts on the intake, removed and cleaned/inspected the EGR valve.....

A guy at work suggested that I dump injector cleaner in the gas tank...what else is left?? Any idea's out there?

After doing all of the above, I erased the codes but the service engine light (with the same codes)came back in 4 days of driving.

BTW, the Expedition idles and runs PERFECT!

Mike Mulhern
Scottsdale, AZ
mmulhern@watsonpharm.com

 

Hi Mike,

Thanks for the comments, it seems that we have the same problem and can't find a solution.

I have run all of the sensor checks described in the Chilton and Haynes manuals and all checks out as okay.

I even paid $80.00 for a diagnostic check at a service shop. They told me to change the MAF Sensor, but I have not done so as yet. Ford wants $193.00 for one and a rebuilt at the parts house is $93.00. I would gladly spend the money If I was sure that would solve the problem.

Ford says all of the following can set the P0171 & P0174 codes.

Fuel System: Excessive Fuel Pressure, Leaking/contaminated fuel injectors, Vapor recovery system. Induction System: Air leaks after the MAF, Vacuum leaks, PCV system, Improperly seated engine oil dipstick. EGR System: Leaking gasket, Stuck EGR valve, Leaking diaphragm or EVR. Base Engine: Oil overfill, Cam timing, Cylinder compression, Exhaust leaks before or near the HO2Ss.

That is a pretty good list to work on.

If I come up with anything I will let you know, and would appreciate if you do the same.


Thanks

 

Joe -- Check out my reply to Dan's [link:www.ford-trucks.com/dcforum/DCForumID93/2553.html|HELP TROUBLE CODE PROBLEM] post. It has some ideas for the DTCs you have.

Cheers from Tulsa, OK!
Dave

 

I searched for this thread cause I am having to fix my '99 Explorer XLS. The check engine light came on this time last year. Perfect timing because my State Inspection is due. I changed the plugs, ran some injector cleaner through and of course disconected the battery for a few hours to reset the computer. After that the light was off and stayed off for a few weeks maybe even a month or two. Well, It is on again and it is time for inspection. Has anyone found a permanent solution? If not, can anyone give me a list of things to do from the cheapest to the most expensive? I appreciate any help.
Thanks

 

you might check the rubber elbow that goes into the back of the engine, follow the pcv plasitic tube, to the back of the engine, on the end is a rubber elbow that plugs into the intake. mine had a small crack in it, creating a small vacum leak, i had gotten the same codes, you might want to give it a try..i wrapped mine in electrical tape , no more codes

 

Hi Fireman and welcome to the forum
Like f=2504by497 said you should check for vacuum leaks.
I would also try cleaning the MAF sensor.
There are instructions for doing that in the FAQ's at the top of the forum.
What engine does your Exploder have? If it has the 4.0 SOHC and it idles rough at all, especially when cold, then it's quite likely that you have leaking intake O-rings.

 

Did you clean the EGR ports when you swapped the EGR valve?
Do a search on that subject, it is a must. Also, the IAC might
be bad. On mine, I had to change the EGR, clean the EGR ports,
and change the IAC to clear all the codes. Like Racer said, see the
MAF cleaning instructions. Small change compared to buying one.

 

My 97 4.0 Ranger had this problem (for a few years). I finally decided to change the plugs & wires. EGR was in two pieces (rust) so I decided to take it to a shop. I has around 100k miles. After this work was done, it still ran rough. The Mech, said the upper intake manifold gasket was leaking. He was able to verify it by spraying around the suspected area. The spray sucked into the gasket area and the engine ran fine for a few seconds.

I had the gasket replaced and the truck runs like new.

Kenny III

 

Hello I just had the code and I replaced the Two oxygen sensers before the Cataletic converter (UP STREAM O2 Sensors at the store) Got them at Advance for 59.00 a piece. Simple to change with a 7/8 wrench. (DO IT WITH THE EXHAUST COOL OR YOU COULD GET BURNED)

since then it has gone away, before it was coming on every other day.

Lance

 

I gave her a tune-up. Changed plugs, air filter, etc. I also changed the PCV valve. I have had no codes for almost two months now. Hopefully, it is fixed. Now, if we can fix the brake problem I am set!