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Discussion Starter · #1 · (Edited)
I'm a decently long time reader (a lot of the posts here have been helpful in the past), but have never actually posted anything here yet. I've been having a long running issue with my 2003 Escape Limited over enriching the fuel air ratio and a slew of other problems including random power loss driving around town or on the highway, terrible gas mileage, and mild stutter when sitting at stops on really hot days (90F+). This has been going on for about seven months now and I can't seem to track the issue down. The engine is at 225k miles, but has had oil changes every 4-5k since 2008 with other regular maintenance such as coils, plugs, transmission fluids etc all being changed at or just before manufacturer suggested interval. The compression is average 190psi with ~2% variation at all cylinders and is only consuming about .5 quart of oil every 4k miles. I do have a recently developed sooty tailpipe tip, and the oil is starting to take on a gas smell.

When on the highway, at 65+mph it seems to have absolutely zero power. If I want to even try to accelerate at 70+ it has to drop into 3rd just to maintain its speed on flat ground (I live in SC low country so by flat I mean FLAT). If I climb any grade/ push the car to accelerate, the engine first hits 100% engine load, will gradually drop down speed, and then be forced to downshift to 4th or 3rd to maintain the speed averaging 85-90% engine load at 3k- 3.5k rpm. There seems to be a vibration as well when the engine revs up from the downshift that persists until it goes back into OD and engine load comes down to 80-85%. This vibration does not happen with the engine in park rev'd to the same rpm. It feels like a half hearted misfire on 1 cylinder, but the OBD never detects a true misfire.

Gas mileage is about 13-14 mpg around town and about 16 on the highway very consistently. It doesn't matter how hard or easy I drive the car. The stutter at stops seems to happen only on really hot days and can be remedied by rev'ing the engine up to about 1500rpm and once I accelerate to the next stop, will not happen again for the rest of the drive.

These issues all started around the same time February of this year. On colder mornings (at least 40F- 35F), I have to crank it for at least 3-5 seconds two times consistently to get it to start. This does not happen every day though. Some days it starts after half a crank, other times it's harder. It then idles/ runs fine.

SO FAR I have replaced with new parts (in the last 10k miles):
  • All plugs (motorcraft)
  • All injectors (motorcraft)
  • All coils/ coil packs (NGK)
  • All intake gaskets (felpro)
  • Valve cover vent vac lines (motorcraft)
  • PCV valve/ PCV vac line (motorcraft)
  • Intake manifold upper plenum due to seized bolts (motorcraft)
  • Both exhaust manifolds/ gaskets (ultra power)
  • Y-pipe/ muffler/ resonator
  • All four o2 sensors (NGK)
  • EGR vac solenoid (SMP)
  • EGR valve (SMP)
  • DPFE sensor (SMP)
  • Fuel pulse dampener (SMP)
  • Fuel sender/ pump (motorcraft)
  • Vapor canister purge valve (SMP)
  • All vacuum lines (only associated with top of engine parts replaced)
  • Air filter
  • Cleaned the throttle body and IAC valve (TP sensor reading 18.5% at idle with foot off the throttle).

As far as data coming off my computer, anytime I use more than 30% throttle LTFT reads 7% flat. This number does not budge and is after at least 100 drive cycles of 15 minutes or more. At idle it reads 0%, but will VERY rarely surge for a second to -25% or +25%. STFT reads all over the place. Downstream o2 sensors read accordingly as to rich (upper .8's - .9's) / lean (upper .2's - .3's) with the LTFT and STFT readings, however upstream o2 tend to be all over the place. Engine load at idle is about 31-40% depending if AC is running or not. On hot days on the highway cruising with AC, ECT sensor reads 196-208F depending if I'm having to accelerate hard or just cruising. My spark advance sits at about 9-13% at idle and typical idle is about 695-705 rpm. Everything sensor related seems to be reacting and reading accurately to symptoms of running too rich.

My question is, what else outside of the things stated could possibly cause the engine to run ultra rich/ have erratic power loss (highway it's consistently gutless, but around town it'll bog down sometimes at stops or take off like it's fresh off the lot). I can supply other OBD data if that helps and I do have a vacuum line gauge, and fuel pressure gauge (fuel pressure is at 64psi with pump on and pump off it does not lose pressure). Thanks for any help and please let me know if I need to clarify more on anything.

3,672 Posts
Dirty MAF? If it mis-reports the amount of air being inhaled... the mix can go rich or lean, depending upon which way it was 'leaning' at the time. (leaning/tilting/feeling...)
Have you looked at the wires? They can get clotted with a tiny bit of bee pollen. (or anything) And then the numbers will be wrong as the clot covers the hot wire so it is not cooled by air passing by. At the same time, the incoming air temp sensor will also need to be providing accurate information as that diddles with the density(thus the MASS part of MAF). If incorrect, the IAT will mix with the MAF info to determine the mass of the incoming air, and thus the injector diddle (time & fuel pressure) to get stoichiometric fuel:air to burn cleanly. OTOH, if the fuel pump DRIVER module, diddled by the ECM, is lazy or over energetic, it could be making the pump run too much and bump fuel pressure above expected. Fuel pressure sensor could mis-report... and so on.
If you have not, getting a scan tool that will let you look at some of the above values may be a good thing to do. The ECM does not know that a temp sensor reporting atmospheric at 22F is incorrect, as is is a VALID measure. If it was 999F, it may throw a code(likely). Kinda the same for all the rest of the sensors. The ECM has (perhaps) a range of 'valid values' from the sensors, and won't flag those that are reading bogus if they are within range.
A readl mechanic would know what the high engine load @idle means. I have not thought through how that would be, but look at fuel flow at idle. The numbers should be close the the displacement in liters.
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