thermostat problems
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thermostat problems
i have been having a rough idle problem which i can't figure out and my gas mileage has also been going south. this past weekend i decided to flush my radiator as it had not been done in a while. in the course of doing this i realized my thermostat was stuck closed. long story short, i didn't replace the thermostat yet, but read somewhere that a broken thermostat could also affect my mileage. how does this work? and could it have anything to do with my idle? sorry im not a gearhead so just consider me ignorant. any help would be appreciated or just a link to a thread or other website that maybe i can read up on this matter.
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If your thermostat was stuck shut your engine would overheat. Now if it is stuck open, the coolant temperature sensor would signal the computer that the engine is still cold. The computer would then give the engine a richer fuel ratio (more gas). This could be the cause of poor gas mileage. The richer mixture could lead to poor spark plug perfomance and a poor idle. What engine is in your 99?
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99 f150 4x4 lariat 5.4 v8
thanks for the correction, but according to my scantool im getting a p0107 code which says im actually running lean in bank 1 if i remember correctly.
im definitely changing out the thermo tomorrow morning and flushing my system again. ill see what happens after that.
im definitely changing out the thermo tomorrow morning and flushing my system again. ill see what happens after that.
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Originally Posted by saxet666
thanks for the correction, but according to my scantool im getting a p0107 code which says im actually running lean in bank 1 if i remember correctly.
im definitely changing out the thermo tomorrow morning and flushing my system again. ill see what happens after that.
im definitely changing out the thermo tomorrow morning and flushing my system again. ill see what happens after that.
<TABLE width="100%" align=center border=1><TBODY><TR><TD rowSpan=2>DTC</TD><TD rowSpan=2>Description</TD><TD align=middle colSpan=6>VIN Digits</TD></TR><TR><TD align=middle>2
Manufacturer
</TD><TD align=middle>3
Division
</TD><TD align=middle>4
Body
</TD><TD align=middle>5
Series
</TD><TD align=middle>8
Engine
</TD><TD align=middle>10
Year
</TD></TR><TR><TD vAlign=top>P0107</TD><TD vAlign=top>Manifold Absolute Pressure [MAP] Sensor Circuit Low Voltage</TD><TD vAlign=top align=middle colSpan=6>Generic OBDII Code </TD></TR></TBODY></TABLE>
Pull the vacuum line off the sensor if it is full of gunk replace the sensor and clear the vacuum line. Good luck and let us know what happens.
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sorry wrong #
my bad i gave the wrong dtc #. its actually p0171. im actually in the process of cleaning the maf, mas, map sensor with crc qd electronic cleaner.
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Originally Posted by saxet666
my bad i gave the wrong dtc #. its actually p0171. im actually in the process of cleaning the maf, mas, map sensor with crc qd electronic cleaner.
I went out and looked on my 98 F150 5.4 for the MAP (manifold absolute pressure sensor), not to be confused with the MAS (mass airflow sensor) and could not find one. I checked the vacuum schematic under the hood and it did not list one. Ford is willing to sell me one online for $39.46?
Code p0171 was as you originally stated "Fuel Trim System Lean Bank 1". Clean the MAF sensor and check for vacuum leaks. The vacuum hoses can be either hard and brittle or soft and gummy and leak. They are a pain to check due to the locationin the back of the engine under the cowl.
If you do a search with just "p0171" you willl find all you need to know. Good luck and let us know how you make out.
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i give up
thanks for the quick reply, but i think ive had it. i cleaned the maf, checked EVERY hose by touch and by spraying carb cleaner. the only other thing i can think of is to check the o2 sensors. if i feel like it, i might try that tomorrow. im just sick of this problem and have mentally burnt myself out trying to figure this thing.
thanks again and ill post results on the o2 sensors and if or when i take it to a garage.
thanks again and ill post results on the o2 sensors and if or when i take it to a garage.
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The good lord is trying to teach you patience. I wish He'd give up on me.
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.
You could try switching the O2 sensors from side to side to see if the code changes to P0174 (left bank lean). Be sure to put never seize on the O2 sensor threads. Good luck either way.
I wish He'd give up on me. 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.
You could try switching the O2 sensors from side to side to see if the code changes to P0174 (left bank lean). Be sure to put never seize on the O2 sensor threads. Good luck either way.