fiesta mk 6 tps 27% at idle

[tomsjapcars]

as title, the tps reading is 27% at idle (high?), ive changed the tps but still get the same reading?

[ohtari]

Is the engine up to temperature when the reading is taken?

[tomsjapcars]

its the same from hot and cold, i may be correct but seems odd, my ltft are at -10% and calculated load is over 25% at idle, its the 1.3 8v duratec, runs ok but mpg is poor

[ohtari]

Does it run fine under load at high rpm? It could be a fueling/air problem as opposed to ecu.

[Pumaracing]

As long as the TPS is somewhere within its range of travel from idle to full throttle and the ecu can read them normally it shouldn't make any difference what the readings are. This isn't your fuel consumption problem.

[tomsjapcars]

ohtari said:

Does it run fine under load at high rpm? It could be a fueling/air problem as opposed to ecu.

it used to miss under load so i changed the plugs, leads (to proper metal insulated ones), lambda and coil and now it runs fine, just seems to be running rich and the tps showing 1/4 throttle cant help

[Pumaracing]

Once again, and for the last time. The ecu doesn't care what the TPS says other than for a signal to go to a full power mixture at full throttle. The MAF or MAP or whatever your car has fitted will be measuring the actual airflow, injecting fuel accordingly and compensating for any residual error via the closed loop lambda system and the long and short term fuel trims.

The most likely cause of persistent high fuel consumption is a defective temperature sender making the ecu think the engine is running cold. Most other faults will be compensated for via the lambda sensor.

[tomsjapcars]

Pumaracing said:

Once again, and for the last time. The ecu doesn't care what the TPS says other than for a signal to go to a full power mixture at full throttle. The MAF or MAP or whatever your car has fitted will be measuring the actual airflow, injecting fuel accordingly and compensating for any residual error via the closed loop lambda system and the long and short term fuel trims.

The most likely cause of persistent high fuel consumption is a defective temperature sender making the ecu think the engine is running cold. Most other faults will be compensated for via the lambda sensor.

ok, my car has a map thats 34kpa at idle, calculated load is 27% at idle, ltft has come down but still in negative numbers, lambda cycles between 0.20v-0.80v consistently, no cel, i will replace cts anyway as part of service

[SuperchargedVR6]

Is this a cable throttle, or a DBW engine? Have you checked the throttle blade is actually closed and not being held open 27% mechanically, such as a stuck throttle cable etc?

Pumaracing said:

The ecu doesn't care what the TPS says

Of course it does. Over run and idle are two very obvious functions triggered by TPS position. I don't know of many engines where 27% open is acceptable for idle and over run duties.

[tomsjapcars]

SuperchargedVR6 said:

Of course it does. Over run and idle are two very obvious functions triggered by TPS position. I don't know of many engines where 27% open is acceptable for idle and over run duties.

thanks for the reply, its 100% closed and its cable, ive had the t/b off and theres nothing wrong there, just wanna no if anybody can plug their fiesta in and see what their readings are for comparison

[SuperchargedVR6]

Seems very strange to have a closed TPS show as 27%. Are you sure it's not just a position number as opposed to a percentage open?

Is it an external TPS sensor that bolts onto lug on the throttle body? Is it possible the sensor isn't in the right static position? I've seen some TBs with tamper paint on the TPS sensors screws.

[tomsjapcars]

SuperchargedVR6 said:

Seems very strange to have a closed TPS show as 27%. Are you sure it's not just a position number as opposed to a percentage open?

Is it an external TPS sensor that bolts onto lug on the throttle body? Is it possible the sensor isn't in the right static position? I've seen some TBs with tamper paint on the TPS sensors screws.

its external with no adjustment on the screw holes, its def 27% as when i apply throttle it goes to 100%, ive taken it all apart, fitted a new ford tps and its still the same

[buggalugs]

As long as the ECU knows that 27% is the closed position then you're fine. If you can read live data then get hot & up to speed and then close the throttle, mixture should go mad lean as you engine brake or at least stop cycling. This would indicate that the ECU knows that the throttle is shut and is cutting fuel accordingly.