I have a 2007 Ford Five Hundred/Mercury Montego, FWD and 6 speed Aisin. 147,000 on the clock.
I am experiencing a issue where I feel a light hesitation only when in a certain RPM range (1,000-1,300) and the engine is under load. For reference, this is around where I'd be driving in the 30-40 MPH range and I think I'm either in 4th or 5th gear. It's right around the load range in which you'd be expecting a downshift at about any moment.
If I floor it from a complete stop, it takes off quickly and shifts through out the gears perfectly with zero noticeable hesitation/shudder all the way to to 80 MPH.
I have NO check engine light and no pending DTC's.
Here's a list of what all I've replaced/serviced at this point:
- Plugs (OEM Motorcraft)
- Coils (OEM Motorcraft)
- Cleaned throttle body very thoroughly.
- Fuel filter (Wix)
- Fuel pump was replaced about 12 months ago with an OEM style Walbro. Didn't replace the basket and sending unit, just the pump and reinstalled.
- Dosed the fuel with Berryman's B12.
- Ran down the tank to nearly empty, refilled.
- Treated the intake with Berryman's B12.
- Cleaned MAF sensor with electronics cleaner and very light shop air.
- Checked air filter, blew out with shop air. It's relatively clean.
- Have checked for vacuum leaks, cannot hear or notice any.
- Flushed transmission with Valvoline MaxLife (TI-V rated), the old fluid was nasty and was flushed maybe 40,000 ago. I did not do a drain and fill. I disconnected cooler lines and let the transmission pump out the old fluid into a pan as I poured fresh in the fill tube.
Anyone have any ideas of what's going on? I hate to keep loading money in the parts cannon, but without a trouble code I'm kind of flying blind.. I've even datalogged the STFT and LTFT's and don't note any anomalies.
Right now I'm leaning towards the shudder being a product of the transmission or torque converter, perhaps - or perhaps a fuel injector is getting lazy. I haven't noticed any transmission slipping though, and I feel like it would really manifest itself when I floor it from a stop, but it doesn't.
I am experiencing a issue where I feel a light hesitation only when in a certain RPM range (1,000-1,300) and the engine is under load. For reference, this is around where I'd be driving in the 30-40 MPH range and I think I'm either in 4th or 5th gear. It's right around the load range in which you'd be expecting a downshift at about any moment.
If I floor it from a complete stop, it takes off quickly and shifts through out the gears perfectly with zero noticeable hesitation/shudder all the way to to 80 MPH.
I have NO check engine light and no pending DTC's.
Here's a list of what all I've replaced/serviced at this point:
- Plugs (OEM Motorcraft)
- Coils (OEM Motorcraft)
- Cleaned throttle body very thoroughly.
- Fuel filter (Wix)
- Fuel pump was replaced about 12 months ago with an OEM style Walbro. Didn't replace the basket and sending unit, just the pump and reinstalled.
- Dosed the fuel with Berryman's B12.
- Ran down the tank to nearly empty, refilled.
- Treated the intake with Berryman's B12.
- Cleaned MAF sensor with electronics cleaner and very light shop air.
- Checked air filter, blew out with shop air. It's relatively clean.
- Have checked for vacuum leaks, cannot hear or notice any.
- Flushed transmission with Valvoline MaxLife (TI-V rated), the old fluid was nasty and was flushed maybe 40,000 ago. I did not do a drain and fill. I disconnected cooler lines and let the transmission pump out the old fluid into a pan as I poured fresh in the fill tube.
Anyone have any ideas of what's going on? I hate to keep loading money in the parts cannon, but without a trouble code I'm kind of flying blind.. I've even datalogged the STFT and LTFT's and don't note any anomalies.
Right now I'm leaning towards the shudder being a product of the transmission or torque converter, perhaps - or perhaps a fuel injector is getting lazy. I haven't noticed any transmission slipping though, and I feel like it would really manifest itself when I floor it from a stop, but it doesn't.