Sudden 30% loss MPG, no symptoms?

[Doug]

Hey ETCG and forum,

I have an 05 Ford Escape 2.3L Duratec (non-hybrid) which suddenly dropped from a consistent 23 mpg to ~16 mpg, with no major mechanical changes to the vehicle, same driving habits, and no CEL! I maintain this vehicle myself and the preventatives have all been kept up per recommendations..

Fuel filter, air filter, spark plugs, clean MAF, oil/ATF (synthetic), alignment, suspension, coolant, belts/hoses…

The only thing due is the PCV valve/hose. It’s recommended to be changed at 100k, but the job requires taking off the intake manifold! I’ll do it someday soon..

The vehicle starts, idles and runs as smooth as it always has, doesn’t leak or burn oil, no major loss of power (maybe a little on the low end?)

I’m not sure where else to look for this kind of loss of MPG with no symptoms! O2 sensors? Stuck caliper? (still need to check that!) Time for a trip to the dealership?

Thanks for any input!

Topic

[Julian]

Hi,

Have you tried hooking ti up to a scanner? Sometimes codes are set, but they’re not major enough to trigger the CEL. Maybe that’ll be a starting point to tracking down the MPG.

Good luck.
Julian

[Mike]

You mentioned a small power loss at the low end. I would pull all 4 wheels and inspect the brakes carefully, especially the parking brake mechanism. It might be possible you’ve got a bit of brake drag for any number of reasons.

Remove wheel covers/hubcaps if you have them, and drive around for about 10 miles, including a short highway stint if possible. Then carefully feel the outside of each wheel rim , around the hub area in the central area. If any one rim is noticeably hotter than the rest, that would be the first wheel to check the brakes on.

[Doug]

Thanks for the replies so far. I took the vehicle for a drive today. Checked all 4 wheels and didn’t notice any hot drums/calipers. I even jacked them up and they spin freely.

I did take it by Advance. Granted they don’t have an advanced scanner–but it didn’t pull any codes.

If the Escape does has any loss of power in the low end, it is minimal at best. This 4-cylinder never had any pep to begin with!

[EricTheCarGuy]

Is this a flex fuel vehicle? If so, there could be a problem with the sensor that monitors the fuel being used. As suggested, start by checking for codes and see what you get there. This article may also be helpful.

http://ericthecarguy.com/faq/finding-and-fixing-the-causes-of-poor-mpg

Good luck and keep us posted.

[Doug]

Thanks Eric. This is not a flex fuel vehicle.

I looked at the Poor MPG link, and I see few things that I haven’t looked at yet.

Are there any particular items below that could cause a sudden loss of ~30% MPG, with little/no loss of power?

O2 sensors
PCV Valve
EGR Valve
Vacuum Leaks
Exhaust Restrictions/Leaks
Fuel System issues
Evap System
Mechanical (hope not!)

[Mike]

I’ve seen your complaint many times over the years, and it frequently goes unresolved. There are so many variables to fuel economy. The two things though that I’ve seen more than once and actually happen, is that either someone is stealing the customer’s gas or the customer’s kid is stealing the car at night while they are sleeping and going out for joyrides.

[Mike]

How are you calculating your fuel economy?

If you are reading it from an information display in the dashboard, perhaps it’s lying to you.

[Doug]

Thanks all. I’m the only one driving, and I’m 99% sure gas isn’t being siphoned.

I am calculating based actual miles between fill ups. I guess I will start by looking at the O2 sensors (they aren’t very expensive).

Am I correct in assuming the upstream would affect MPG?

[Lee Ann]

[quote=”ManFromEast” post=143631]

I looked at the Poor MPG link, and I see few things that I haven’t looked at yet.

[/quote]

Keep it simple to begin with. I would start there at the Poor MPG link and try those suggestions first.
I know this seems rudimentary but are your tires inflated to the appropriate pressures as listed on the sticker in the door jamb?

Then after that you might consider checking into performance issues. Do you have any exhaust system leaks?
http://www.ericthecarguy.com/faq/solving-automotive-performance-issues
Why take it to the dealer if you don’t have to? I think if you are patient, you can do this yourself. There is a lot of information and many knowledgeable people on this site to help guide you through this. Keep us posted on your progress.

[Bluesnut]

What about tire pressures? One low tire can kill fuel mileage.

[Doug]

I picked up a wifi OBD2 scanner and am using an applicaiton called FORSCAN to pull PCM data.

Graphed in the attached pic are

coolant temp
short term fuel trim
long term fuel trim
MAF
upstream sensor voltage
downstream sensor voltage

When idling, the upstream O2 sensor is oscillating every ~2 seconds. At 2200 RPM, the oscillation is very close to one second.

The downstream looks like it’s bouncing quite a bit. Could this be a sign of a bad cat? or could the upstream just be bad?

Attachments:

• 1.jpg

[Doug]

Replaced the PCV. Turns out on the 2.3 duratec, the hose that connects the PCV to the intake manifold is prone to collapsing and cracking. I found 2 huge cracks in mine. 24.5 MPG on my last trip.. better than EPA! Hope this helps someone.

[John B Kobberstad]

Have you checked the fuel pressure? Does the pressure hold or drop? Do you smell raw fuel at any time?

[Author]

Replies