CumminNotRunnin
Internet Mechanic
- Joined
- May 7, 2007
- Messages
- 1,090
Been fighting with a truck for a few weeks now on and off.
The engine will stumble with the A/C off. Soon as you command A/C on the engine smooths right out.
Balance rates are ok and FRP is spot on between actual and desired. This seems to be electrical because it happens almost to the degree of 170* it will start acting up.
Also noted with A/C off and engine stumbling the balance rates all go to Zero and CMS on cylinder 7 and 8 drop from and average of .45-.63 To a spread of .00- .63. Just on cylinders 7&8.
Soon as you kick the A/C on and put load on the engine the Balance rate come back and the CMS smooth out to an average of .43-.55.
The two major determining factors that are exact every time is the temp of 175* it start doing it immediately. Meaning it will not do it when cold. The other factor is the A/C command will every single time turn the Skip on and off.
Parts, we have changed or replaced so far: 8 bosch injectors, FICM, Crank and Cam Sensor, Performed ICE pick test, Checked the FICM control harness for rubs on the alternator. Non found. There is also no diagnostic codes logged.
Truck has EFI Live tuning. Still does the same thing on stock tunes.
Please feel free to comment below with any information or you can call me at the shop the discuss more detail.
Thanks in advance
Jake 973-668-9242
The engine will stumble with the A/C off. Soon as you command A/C on the engine smooths right out.
Balance rates are ok and FRP is spot on between actual and desired. This seems to be electrical because it happens almost to the degree of 170* it will start acting up.
Also noted with A/C off and engine stumbling the balance rates all go to Zero and CMS on cylinder 7 and 8 drop from and average of .45-.63 To a spread of .00- .63. Just on cylinders 7&8.
Soon as you kick the A/C on and put load on the engine the Balance rate come back and the CMS smooth out to an average of .43-.55.
The two major determining factors that are exact every time is the temp of 175* it start doing it immediately. Meaning it will not do it when cold. The other factor is the A/C command will every single time turn the Skip on and off.
Parts, we have changed or replaced so far: 8 bosch injectors, FICM, Crank and Cam Sensor, Performed ICE pick test, Checked the FICM control harness for rubs on the alternator. Non found. There is also no diagnostic codes logged.
Truck has EFI Live tuning. Still does the same thing on stock tunes.
Please feel free to comment below with any information or you can call me at the shop the discuss more detail.
Thanks in advance
Jake 973-668-9242