check eng light on, temp guage doesn't work, coolant is cold after driving, and codes read lean fuel?

Question

Just got real cold around here recently. Check engine light just came on, heat blows not very hot, temp guage doesn't move at all, coolant is cold even after long drives, coolant is full, and codes read lean fuel on both banks. car is 1998 Ford Explorer 4.0 SOHC, What do I check now?

Answer 1

i would check the oxygen sensor especially if it has lost power

Answer 2

The thermostat is most likely stuck open. Replace it. That should take care of your "no heat" problem. While you are at it, refresh the coolant. Most likely way past time.
DO NOT clear the codes until you can see the "freeze frame" data. It is conceivable that the code was set due to the thermostat, but you should be sure.
If the PCM "sees" the engine cold, it adds fuel (remember chokes?) until it warms up.
it is also possible that it is unrelated, and is really "seeing' a lean condition. It could be due to...
1) Failing Fuel Pump
2) Restricted fuel filter
3) Failing pressure regulator
4) Vacuum leaks
5) Exhaust leak before the O2 Sensor
6) O2 sensors slow or locked
7) MAF sensor out or calibration (or bug guts)
These are some things to look at.

Good Luck and Merry Christmas

Answer 3

If the engine is not coming up to operating temperature when it is real cold it is going to be your engine thermostat. It is located where your upper radiator hose goes into the engine. Usually two bolts to unbolt the thermostat cover.
Go get new thermostat first at your parts house at the temperature your make and model calls for. Just tell your parts dealer what make model, engine, and whether it is an automatic transmission or manual transmission. He will look up the right temperature rated thermostat.

While you are there get some anti seize and some high temp RTV.
If you radiator hoses and belt looks worn you might want to change them at the same time:

When you home let engine cool down first, then remove upper radiator hose from where it goes to the engine.
after you get the housing off make sure you check how the orginal thermostat is mounted (the direction it is turned) so you can put the new back in the same way.

Clean the where the old gasket was on both surfaces, the engine block and the thermostat cover (housing) so it will not leak when put back on. You will probably have to scrap them clean.

Coat the threads on the bolts with some Anti Seize.

Coat the thermostat surfaces on both the engine and thremostat housing with a thin layer of RTV

Slide the bolts through holes in thermostat housing. Place gasket on thermostat housing threading bolts through gasket's bolt holes. Press it on is the RTV will hold it so it does not fall off.

Put the thermostat in engine making sure it is turned the right way. Put the thermostat holding on and tighten the bolts.

Put the upper radiator hose back on fill with proper anti freeze water mix.

Put radiator cap back on start engine turn the heater on to full heat.and run to engine is up to temperature. Turn off and let engine cool down. refill with anti freeze water mix. (You do this to work air out of cooling system you might have to do this several times). Start engine and run up temperature again then let it cool and check water again if needed fill again.

Answer 4

the thermostat would be a good place to start but since the temp gauge doesn't work either it's possible you have a bad coolant temp sensor also. Alot of newer cars use coolant temp,to adjust fuel ratio. so if the sensor is inopertive it can cause a lean condition and a check engine light to go on. Good luck

Answer 5

a stable mechanic could desire to degree the truthfully coolant temp and evaluate it to the sensor reader on a expert grade test gadget. If the temp is larger than the test gadget shows, that would warrant changing the sensor. If the truthfully temp is low and coupled the sensor examining, then the undertaking lies someplace else. The chilly start up undertaking shows that it could not the coolant temp sensor. while the engine is chilly, the european runs the engine in "open loop" mode, and forces the ignition timing and air-gasoline mixture in keeping with an inner table of preset values. while the engine warms up, besides the undeniable fact that,the european calculates the mixture and ignition from examining taken from countless sensors obtainable issues different than the coolant temp sensor are: Vacuum leak or air leak between the air filter out housing and throttle physique, undesirable thermostat sensor creep interior the IAT, O2, and MAP/BAP sensors (if so equipped corroded or broken sensor wiring. undesirable plugs or plug wires

Answer 6

Someone always has to throw O2 sensor out there don't they.

Ignore the O2 sensor response. Irrelevant. First problem to deal with is our complete lack of heat. Most likely culprit here would be the T-Stat, especially if it is original. Replace the thermostat, burp the air out of the system and if you get heat, delete the codes from the PCM. Then run it to see if any codes return.

I suspect your lean running condition is actually temp related.

Answer 7

replace the thermostat first, this is cheap to do.
disconnect the battery while doing this and this will clear the codes.
start and run to operating temp and see what happens.

Answer 8

Replace the thermostat.