Technical 1.2 fuel problem

[billynomates]

Hello, I have a strange problem with my 2004 1.2 that is sending me crazy! I keep getting the p300 code (intermittent misfire) and in the freeze frame, the short term and long term fuel trim are all over the place! one day the long term is -57% and the short term +25, other days they are reversed! Also on the fuel computer, it says say 250 miles left on tank, the next minute it will say 125! Is there a problem with a fuel sensor or has the ECU shot it?
When i have long term trim of -55%, surely i should get a obd2 code warning me??
Im confused! The car runs fine

 

[murfman53]

Hi,

I take it you mean PO300 code. According to that code, the cause could be a number of issues.

Spark plug (s).

HT lead (s).

injectors (s).

ignition coil (s).

low compression.

wiring.

Have you checked any of the above, to rule them out.

John.

 

[varesecrazy]

Hello, I have a strange problem with my 2004 1.2 that is sending me crazy! I keep getting the p300 code (intermittent misfire) and in the freeze frame, the short term and long term fuel trim are all over the place! one day the long term is -57% and the short term +25, other days they are reversed! Also on the fuel computer, it says say 250 miles left on tank, the next minute it will say 125! Is there a problem with a fuel sensor or has the ECU shot it?
When i have long term trim of -55%, surely i should get a obd2 code warning me??
Im confused! The car runs fine

is this 8Valve - or 16V,
the earth cable to throttle body can be an issue..if fitted.

 

[billynomates]

still getting the same crazy fuel trim readings! I have checked everything mentioned, one minute the fuel gauge reads half full, a minute later it reads a quarter, same as the temperature gauge

 

[murfman53]

Hi,

Have you considered the MAP unit. Also the throttle body unit.

Had the same problem recently, and discovered the above units needed a good cleaning.

Once done, all was fine.

As a matter of interest, does the engine remain in CLOSED LOOP, or will it go into

OPEN LOOP after a little while?

Might be an issue with temperature sensor.

John.

 

[varesecrazy]

billynomates ....