Stumbling and high fuel consumption
24-01-2012, 04:29 PM
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Stumbling and high fuel consumption
Hello
To all of other posts about driviability problems with Ford Focus ST170 (SVT), I'm adding mine. I'm running out of ideas and I don't have a lot of mechanically experienced people around me to turn to.
My main problem with a car is poor engine performance and big fuel consumption. I have read tons of articles, discussions on forums etc. tried a lot of stuff, but with little or no success.
Car has 77.000 km (48.000 miles) on it. Currently I don't have CEL light on. Car stumbles a lot, especially around 1800-2500 RPM. Fuel consumption is 11l/100km (21.5 mpg). I'm driving him half on the motorway and half in the city. Stumbling is pretty obvious when cruising with constant speed. On acceleration it is not so noticable. Running idle is normally pretty smooth (sometimes he has it's own moments with surging on idle, but normally not). I have a feeling that problem with stumbling gets more obvious when engine is hot. Also for the first minute when engine is cold he barelly has the power to drive off.
Things I did, to get rid of that problem:
- changed coil pack
- changed MAF (two different)
- repaired IMRC (transistor)
- cleaned throttle body
- changed air filter
- changed fuel filter
- changed both of o2 sensors
- used fuel additive for cleaning injectors
- made "the big three" wires upgrade to make sure that + and - on the car are getting constant flow
I also checked for:
- vacuum leaks (trick with a vacuum cleaner) - didn't found any
- i don't suspect fuel pump, since stumbling is same at all times. When tank is full or empty.
- compression in cylinders is in normal range (within same range on all cylinders)
- coolant temperature sensor works fine
- TPS sensor gives voltage constantly without glitches
- resistance on fuel injectors is in acceptable levels
- knock sensor seems OK
- PCV valve looks alright also
Seems also that car is running rich. Spark plugs are always pretty sooted and so are o2 sensors in catalyst.
Last time i tried to fill the tank with 100 octane fuel. Engine almost died on me. Fourth cylinder was misfiring so bad that it was actually dead. That was really shaky ride. I bought some "random" spark plugs next day - first one i could find and ride became tollerable, although I have feeling that it still actually misfires here and then. So my next step would be to buy some super-duper spark plugs and to change HT leads (resistances on current leads are barelly in acceptable limits). But I must say that I don't have high hopes, so I'm asking you people if you have any other idea that I haven't tried yet.
PS: I also have "SCT Xcalibrator 2" (like Bluefin) flash device, that also reads all engine codes and gets to all engine sensors in real time, if someone would have any such test on mind.
PPS: Sorry for my clumsy English at times
To all of other posts about driviability problems with Ford Focus ST170 (SVT), I'm adding mine. I'm running out of ideas and I don't have a lot of mechanically experienced people around me to turn to.
My main problem with a car is poor engine performance and big fuel consumption. I have read tons of articles, discussions on forums etc. tried a lot of stuff, but with little or no success.
Car has 77.000 km (48.000 miles) on it. Currently I don't have CEL light on. Car stumbles a lot, especially around 1800-2500 RPM. Fuel consumption is 11l/100km (21.5 mpg). I'm driving him half on the motorway and half in the city. Stumbling is pretty obvious when cruising with constant speed. On acceleration it is not so noticable. Running idle is normally pretty smooth (sometimes he has it's own moments with surging on idle, but normally not). I have a feeling that problem with stumbling gets more obvious when engine is hot. Also for the first minute when engine is cold he barelly has the power to drive off.
Things I did, to get rid of that problem:
- changed coil pack
- changed MAF (two different)
- repaired IMRC (transistor)
- cleaned throttle body
- changed air filter
- changed fuel filter
- changed both of o2 sensors
- used fuel additive for cleaning injectors
- made "the big three" wires upgrade to make sure that + and - on the car are getting constant flow
I also checked for:
- vacuum leaks (trick with a vacuum cleaner) - didn't found any
- i don't suspect fuel pump, since stumbling is same at all times. When tank is full or empty.
- compression in cylinders is in normal range (within same range on all cylinders)
- coolant temperature sensor works fine
- TPS sensor gives voltage constantly without glitches
- resistance on fuel injectors is in acceptable levels
- knock sensor seems OK
- PCV valve looks alright also
Seems also that car is running rich. Spark plugs are always pretty sooted and so are o2 sensors in catalyst.
Last time i tried to fill the tank with 100 octane fuel. Engine almost died on me. Fourth cylinder was misfiring so bad that it was actually dead. That was really shaky ride. I bought some "random" spark plugs next day - first one i could find and ride became tollerable, although I have feeling that it still actually misfires here and then. So my next step would be to buy some super-duper spark plugs and to change HT leads (resistances on current leads are barelly in acceptable limits). But I must say that I don't have high hopes, so I'm asking you people if you have any other idea that I haven't tried yet.
PS: I also have "SCT Xcalibrator 2" (like Bluefin) flash device, that also reads all engine codes and gets to all engine sensors in real time, if someone would have any such test on mind.
PPS: Sorry for my clumsy English at times
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