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- What I Drive
- 2008 Fiesta 1.25l Zetec Blue Edn
Hi,
Having an issue with my 2008 mk6 (mk5.5) Fiesta 1.25l Duratec engine and wondering if anyone can help. Mileage is 66k.
The car appears to be misfiring intermittently and hesistant in low revs. The car struggles to build power unless flat out on the throttle and high revs. However if I turn the car off and on again and continue to drive, it runs fine until the next idle or sometimes after few minutes again where you feel the car is struggling.
The car had an EML showing P0171 and P0172 error codes with a check engine light but they have been cleared. Recently got P0172 showing again since doing the following fixes from my mechanic:
- Engine temp sensor
- New spark plugs
- New coil pack and leads
It's had a new O2 sensor fitted around Jan 2025 so there is a chance this could be faulty again. However reading the live data shows the following:
O2 sensor is cycling between 0.1 and 0.9v so appears normal
MAP sensor appears normal. Runs at 30-40kPa and with throttle goes up to 90-100kPa.
Short trim fuel goes to -25% when misfiring otherwise its around -5 to 0%
Long trim fuel is sitting around 1 and -5%
I’ve attached an image from Forscan DTC.
My suspicions now are to do with Fuel system, either injectors, rail or fuel pressure regulator?
Wondering if anyone has any idea what it could be and if anyone has had the same issue before. Look forward to hearing all your thoughts
Thanks
Having an issue with my 2008 mk6 (mk5.5) Fiesta 1.25l Duratec engine and wondering if anyone can help. Mileage is 66k.
The car appears to be misfiring intermittently and hesistant in low revs. The car struggles to build power unless flat out on the throttle and high revs. However if I turn the car off and on again and continue to drive, it runs fine until the next idle or sometimes after few minutes again where you feel the car is struggling.
The car had an EML showing P0171 and P0172 error codes with a check engine light but they have been cleared. Recently got P0172 showing again since doing the following fixes from my mechanic:
- Engine temp sensor
- New spark plugs
- New coil pack and leads
It's had a new O2 sensor fitted around Jan 2025 so there is a chance this could be faulty again. However reading the live data shows the following:
O2 sensor is cycling between 0.1 and 0.9v so appears normal
MAP sensor appears normal. Runs at 30-40kPa and with throttle goes up to 90-100kPa.
Short trim fuel goes to -25% when misfiring otherwise its around -5 to 0%
Long trim fuel is sitting around 1 and -5%
I’ve attached an image from Forscan DTC.
My suspicions now are to do with Fuel system, either injectors, rail or fuel pressure regulator?
Wondering if anyone has any idea what it could be and if anyone has had the same issue before. Look forward to hearing all your thoughts
Thanks
