Ford F150 - fuel problems

Truck was getting horrible gas mileage and hesitating on hills or during heavy acceleration. The check engine light began flashing. Pulled over and restarted. Pulled codes and got oxygen sensor codes. Back sensor had bare wires from previous fix, so replaced sensor and sealed new connections. Then the truck began running worse than before. Was hesitating and after warming up would lose power and only do 10 mph even with heavy acceleration. Could restart and the truck would run fine until warm. Pulled codes and this time got several codes, maybe 8 codes that didn't come up last time. The new codes were: ford codes: P1151 & P1131- maybe someone could shed some light on these codes for me? The other codes were: P0102-Mass airflow, Pp0155- oxy sensor circuit malfunction heater circuit, P0301-cylinder 1 mis-fire, & P0335- crankshaft position sensor malfunction. Any and all suggestions/comments would be much appreciated.

You can probably find those code definitions at this link, but remember: a code definition ONLY tells you where to start your diagnosis - not to replace any parts.

Some of those codes conflict, which makes me think 1) you have some more bare wires, or 2) you turned the key on while you were working on that oxygen sensor. What are you using to get the codes? Are you clearing them all each time? Do you have a good shop manual for that truck? Look for a Ford disk. If you can't find one, e-mail me. I have them all.

Sounds to me like catalytic conv. issues. I had a 300 I-6 that did that and found the plastic "T" valve upstream in the emmissions melted and the cat clogged. Maybe just a coincidence.

Icerat
The plastic (TAB/TAD) valve melted after one of the check valves blew out.

. .

After that, the converter clogged because it wasn't getting enough air. The converter problem was the LAST in that sequence.

steve83 i am having the same problem with my 1994 ford f150 5.0 efi changed the oxygen senor twice run fine for awhile then stared doing again could the converterand teb/tad be whats wrong with mine as well

Not likely - they don't directly affect the engine; only emissions. Have you pulled your codes? You can use a paperclip to pull your codes since your truck is EEC-IV. Have you done ALL the normal recommended maintenance? What was wrong with the other oxygen sensors? Is it a MAF engine (how many big rubber tubes connect to the air filter box)?

steve83 i pulled the codes yesterday with my obd1 code reader the first part of the scan pasted but the second part did not pass it pulled 4 codes from my cont.memory they are (172,173,181,668)my resreach has told that 172,173& 181 are from my maf sensor and that it may going out but what does the 668 code mean my haynes manual does not show or tell me nothing about this code all i know is what my little white code book is telling and it says something about my transmission range sensor circuit above maximum voltage i can not find any more research on this any info would help thanks

Change the fuel filter and check the air filter first. I would draw a sample of fuel to look for contamination.

Click the link in my previous post for more info, and a link to the full code list.

Codes don't come from sensors - they come from the EEC. Don't pick one word or the name of a part out of the definition; read & understand the WHOLE thing. You also have to understand how the EEC manages the engine to really understand what a code means. For instance: these trucks often set codes for "insufficient EGR flow". But most of them don't have a sensor or any way of knowing how much flow there is, so that code actually refers to a fault in the EVR or EVP circuits. Remember that most fault codes reference an electrical circuit, as viewed by the EEC. So a fault in that circuit could be a poor connection at the EEC, a wiring fault between the EEC & the sensor/actuator, the sensor/actuator itself, or the interface between the sensor/actuator & the engine.

Also, some sensors will go out-of-range due to something FAR away. Oxygen sensors can show lean due to an exhaust leak at the manifold, and the EEC might set a MAF sensor code due to a transmission fault, or a clogged fuel filter (as GYS mentioned).

So don't throw part$ at codes - it's not likely to fix anything. A code only tells you where to BEGIN your diagnosis - it's not the END of the diagnostic procedure.

Re: 668 Do this, in this order:



Then find the article about water intrusion into the MLPS (DTR) in this thread, then use Haynes' diagrams & a multimeter to test it.