I have a fuel mileage issue with my 2005 Escape Hybrid, I think I know what may be going on but before I go ahead and spend money correcting the suspected problem, I wanted to get some feedback from the folks here who may have experienced something similar.

Al little history.
I bought this vehicle new, it had 11 miles on it when I drove it off the lot in March 2005, my mileage then averaged between 30 and 32 mpg. I now have nearly 317,000 miles on the vehicle. So I expect that there will be issues. At 300,000 miles I was getting approximately 25 to 27mpg, I attributed this drop to age, high mileage and a hybrid battery that was probably performing at something less the optimal at 300,000 miles. This condition continued for about a 6 months, I was at times, getting random P0171 emissions codes that when I cleared with my OBD scanner would not come back immediately so I was waiting to confirm what the failure was before I went ahead and just stated replacing parts.. I recently blew a bearing in the engine and had it replaced at approximately 315,500 miles with an JDM engine that I was told had 41,000 miles on it, impossible to verify, but I believe it. Since the engine was replaced, the mileage has dropped to between 21 to 23mpg and I get rather regular P0171 emission codes that when cleared come back after a few days. All my research indicates that the probable cause is most likely the Mass Air Flow sensor, but like I had said, I'd like to get some feedback on this before I go ahead and spend the money. this sensor isn't cheap.

Anyone have a similar experience?

R/
Prescott ...

 

"JDM Engine" is interesting, as the FEH was only sold in the USA. Actually the (previous gen) Ford Escape was never sold in Japan at all, only the Mazda Tribute (and the ~350 2010 Mazda Tribute Hybrids were only sold in California AFAIK).

Would be really interesting to see what you've got under the hood. 21-23 mpg is probably typical for a non hybrid FEH.
Curiously, are you still able to run up to 30mph in electric only mode and get regen braking, idle/coasting engine shutoff, and all the normal hybrid functions?
Can you still do the FEH tricks like throw the transmission in R when speeding down the highway or drive around comfortably all the time in L?

 

The engine is a 2.3 liter, probably came out of a Ford Fusion I'm told, but the seller claimed that it came out of an FEH, clearly not true if it IS a JDM engine. The only difference between the hybrid 2.3 and the "regular" 2.3 is the cam shafts (or so I'm told). Everything was swapped out during the install, including the cams, so I expect that what I got under the hood is a FEH 2.3L. Yes it has all the hybrid features, up to 30mph on battery (not quite as far as it used to), regen braking and idle/coasting engine shutoff. All the normal hybrid functions. I even checked to make sure that the electric assist was functioning as expected. It is. The only problem I'm having is the 21 - 23 MPG, coupled with the P0171 emissions code (running lean), there are no other issues. CLEARLY it's not running lean, in the morning when I first start it up, it is actually running too rich judging by the way the engine sputters/nearly stalls. Once it runs a few seconds, it clears up and runs normally the rest of the day. I still believe that I have a faulty/dirty MAF unless someone else has other ideas.


R/
Prescott ....

 

I had a bad MAF on my FEH at about 130k miles, it actually didn't throw any codes and mpg was only slightly off. Idle was rougher than normal. The Ford dealer had to get their 'fuel trim technician' to correctly diagnose.
The Fusion hybrid didn't come out until '09 (with a different 2.5L ICE), so if your engine was a 2.3L out of a Fusion it would not be a match for a (2.3L) FEH's. Could also be an issue that your (hybrid) ECM won't read all of the engines' sensors 100% correctly or your new ICE doesn't have the lower power Atkinson cycle that an FEH.
You'll probably need a Ford diagnostic computer to verify what's going on. Or you can buy some new parts and see if you get lucky.

 

It's definitely a 2.3L, the mechanic at the dealership who installed the engine remarked that he thought it came out of a Fusion, not a hybrid.


Early on when the FEH first came out, I was bringing it to one particular dealer to make whatever repairs I couldn't handle myself and he was pretty competent, he apparently has left that dealer. I brought the vehicle back there to have a brake hose replaced and they wanted to charge me $900 to bleed the brakes. It was obvious to me they had no idea what they were doing. I've had it diagnosed three times at the 3 separate dealers in my area (before the engine blew). They each came up with a completely different diagnostic. Consequently I no longer trust the dealers in my area.


I've been looking at the following software https://www.autoenginuity.com/products/scan-tool.html thinking I could diagnose the vehicle myself, your thoughts?


R/
Prescott ....