Mk1 2004 Focus 1.6 With P0171 Code

[ultimate green rs]

I been trying to fix this fault on a 1.6 Focus with Zetec SE engine. Last year at times it would have been hesitant holding back etc. The P0171 fault code had flag up. I had change a few parts, these being fuel filter, spark plugs, coil pack, MAP sensor (used), and it still was eventually bringing the light up.

I recently did a clutch change as the clutch was slipping, car done 92k miles. The car is now seriously running like a bag of crap. I have tried almost every avenue. It hesitates badly. Idles like a pig, many times does not start first time. I could be cranking forever, then if stop, then try to restart, it would fire up first time. But then after it would do its usual trick and eventually die. I could rev it, but it may stutter still. Or very difficult to rev unless pedal to flow for it to bring up revs. If engine is eventually warmed up, it may behave a slight bit better.

I am seriously confused. I had just changed the lambda sensor thinking that would cure it. Removed fuel pump connector sprayed with electrical contact cleaner. Also sprayed connectors of, throttle position sensor, idle speed control valve, crankshaft position sensor, ignition lead wires, coilpack connector.

I also had remove the red connector supply fuel pipe at the fuel pressure regulator and was surprised it was kind of dry. Reminds me of when you attempt to depressurise the system when you want to replace a fuel pump by removing the fuse. I had even thought it may be an airleak. So sprayed easy start around hoses and nothing. Only hose that had cause for concern was one of the T piece connector behind the inlet manifold. The long one to the left had collapse but wasn't leaking, so I replaced it with some other air compressor hose I had from parts bin, which appears to be stronger than original. But still no joy.

I also checked faults yesterday and came up with new codes of P1131 (manufacturer control), P1130 (manufacturer control) as with the usual P0171, cleared them, but still no joy.

Anyone had the same fault yet?

[wayne.m]

No expert but just a thought, have you changed the fuel filter?

[ljm183]

Code P1131.

The heated oxygen sensor (HO2S) voltage is less than 0.45 volts. This is usually due to a vacuum leak after the MAF.

It can also be caused by a bad PCV valve or PCV system hose. It can also be caused by low fuel pressure.

[ultimate green rs]

I had change the fuel filter last year.

No expert but just a thought, have you changed the fuel filter?

[ultimate green rs]

A little update on this

I tested the fuel pump on this (but not for pressure) by removing the white supply collar and the fuel pump worked as normal. I made a mistake as the red collar was the return.

I did all kinds disconnecting sensors etc. I finally found some avail when I disconnected the throttle position sensor. I don't know if its meant to be freely rotated with no resistance when disconnected from the throttle body. The ones I have been accustom to in the Escort has spring pressure, and always returned back to idle when removed.

The car had run much better when the throttle position sensor removed and returned to idle position, but still connected to the connector. It drove like normal; but was still a little difficult to start, i.e. not on first attempt or after 5 seconds. The car also run a little rich. If I rotated the TPS with a screwdriver it would stall or run rough.

I'm not sure of the resistance values of the TPS for this car, cant find it anywhere.

[ljm183]

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[ultimate green rs]

Thanks