getting poor gas milage

[tieoneon]

getting poor gas milage *****UPDATE*****

My 2000 Explorer w/ a V-6 used to get about 350 per tank full. All of a sudden I'm getting around 290 miles per tank full. Engine seems to run smooth and strong. Any ideas why the mpg's would drop so far so fast? I'm getting CEL codes of 171 & 174. Thanks for any help you could provide.

 

[bmxking5]

Both of those codes are for the air to fuel ratio. When I searched google, this turned up: "Code 171/174 Lean exhaust bank1/bank2"
"If your O2 sensors are OK then check your fuel and induction system for the following : - correct fuel pressure at the injectors - air leaks into your intake system (air ducts, inlet manifold etc... - clogged or missing air cleaner - clogged or missing fuel filter - clogged or leaky fuel lines or injectors - disconnected fuel injectors or vacuum lines - exhaust system leaks especially before the oxygen sensors - correct exhaust back-pressure "

http://www.iequus.com/assets/manuals/3145_FDCR_(E)_20NOV2002.pdf

Hope this helps. Bryan

 

[ExplorerDMB]

The codes mean this:

P0174 System too Lean (Bank 2)
P0171 System too Lean (Bank 1)

I'd check for a vaccum leak possibly. Also, clean your MAF as it may be dirty. I found this: this might be helpful

http://autorepair.about.com/cs/faqs/l/bl903d.htm

Good luck

-Drew

 

[Rhett]

What Bryan said, plus don't forget that most people get lower mileage in cooler weather, you might be seeing part of that decrease from that. No question the CEL code probably accounts for most of the drop though...and if you have more than say 80,000 to 100,000 miles on the truck, it could be the O2 sensors.

 

[tieoneon]

Thanks for the replys. Vehicle has 90,000 miles. I cleaned the MAP & IAC already, no help. Any other ideas?

 

[BuffaloXplorer]

If the ratio is lean, then it's likely getting too much air or measuring it incorrectly (o2 sensors), as they said...vacuum leak or bad sensors...

 

[Rhett]

Check the air intake for cracks. Start at the air filter, and inspect all the way to the throttle body. See if the plastic intake tube is cracked or has scuff holes. Check the rubber joints where it joins the MAF and TB, make sure the clamps are tight there and the rubber is not ripped.

Look at all of the rubber vacuum hoses going into the upper intake manifold. Make sure they are not cracked or falling off. Further, you may have some plastic caps on the vacuum "octopus" on the upper intake manifold. Often these caps fall off.

And when I got lean CEL codes, it was the O2 sensors.

 

[tieoneon]

Thanks again for the replies. Is there any way to check O2 sensors? Maybe with an Ohm meter? What should aceptable reading be? Again, thanks for all the help & suggestions.

 

[JDraper]

Yes, you can check them with a digital voltmeter. Best bet is to go buy a Haynes manual, which costs about $15. It has the complete procedure on how to test the O2 sensors, and which wires to probe.

 

[aldive]

Thanks again for the replies. Is there any way to check O2 sensors? Maybe with an Ohm meter? What should aceptable reading be? Again, thanks for all the help & suggestions.

An OBD scanner will monitor the function of the O2 sensors.

Good luck .......

 

[tieoneon]

Well I finally got around to working on my poor fuel economy. Not that I procrastonate or anything. .... I just turned 100 k on my Explorer so I thought I'd do a little PM. Decided to change the fuel filter. I could not believe the the fuel that came out of it. From the inlet side it came out as dark as coffee. The outlet side was really clean. I figure it had a lot of restriction and that must have caused rhe lean condition to trigger the CEL. Anyway, it seems to have recouped all those lost MPG's. I haven't refilled yet, but I got an tremendous inprovement on the half a tank I had left when I changed the fuel filter.
A special thanks to BMXKING and the rest for suggestions. I hope I can get back to the 350 miles per tank level.
Thanks again.