Hello, I am at my witts end and don't have the $$$$$$$$.$$ to take it to a dealership. Need some advise on where to look.

2001 escape xlt 3.0 AWD 154k
began to throw generic cylinder 2 misfire codes about a month ago.
When fuel level is very low, it doesn't want to start (used heet, helped? unrelated?)
Fuel Economy has taken a HUGE hit (estimated 8 mpg)
Runs perfect at startup....gets worse as engine warms up
More pronounced with high load (downshifting, etc.)


Replaced all plugs
Replaced #2 Coil and cleaned connections (later testing showed it was ok)
Ran 2 Tanks of Premium through it with FI cleaner
quick look for leaks

With Christmas and winter approaching I need my wife's escape back on the road and in good shape.

Thanks
George

 

When it is cold the engine gets extra fuel. When it warms up the computer dials the fuel volume back. Teh computer takes the clues from the ECT sensor (Engine Coolant Temperature sensor), the Air Intake Temperature senor and the MAF sensor. The nice thing is you don't have to swap parts just to find out "it wasn't that". You can test the sensors and you can clean them. The Haynes manual and google searches will get you the voltage values for your car and digital multimeters are cheap enough.

Another place to look at are all the vacuum lines. I would also check the fuel pressure and the fuel pressure regulator. If the membrane in the regulator leaks extra fuel goes into the intake manifold.

Good luck!

 

Good point - also look for seal problems on the intake manifold. If the engine sucks false (un-metered) air, the mixture is enriched to make up for the extra oxygen seen in the exhaust, so the fuel economy drops dramatically while the engine runs like s***. Spray some carb cleaner on the intake manifold seals and on all vacuum lines and their connections, and look for changes in engine idle speed. You'll see a change when you hit the broken seal.

One other thing worth checking is the fuel pressure - if it is too high, your injectors will spray too much gas, enriching the mix and causing low fuel economy and crappy running engine.

Also, from a recent personal experience - a bad spark plug cable will also cause these kind of pains, so if your cables are old, you might as well put new ones in, along with new spark plugs on all cylinders ... even if only to rule out a possible cause for misfires. If they're original (at 154k), you'd better put new gear in anyway.

HTH ... Good luck!

 

Also make sure that the brakes are not binding. If they are not releasing all the way you will compensate by advancing the accelerator and the computer will shift at higher RPMS etc. Something like this can creep up on you without notice.