The truck runs very rough at steady RPM with no load on engine. Cruising down the highway the truck will start cutting out and never goes any further than that but I rebuilt a set of factory throttle body heads and changed the camshaft to a Crower camshaft with a 112 degree lobe separation and not much more lift than the factory cam. The cam is able to maintain proper vacuum at idle and at steady RPM`s. I changed the rocker arms out and put a 1.6 roller rocker on the intake and 1.5 on the exhaust. The truck runs phenomenal when you have your foot in the floor board. Cruising at steady seems to be a problem. The Idle is a little rough due to the nature of the cam. Just a little choppy but not to the point the engine is surging, and throttle response off idle will squall the tires into second. There are no vacuum leaks and the engine has a steady 150 pounds of compression on all 8 cylinders. Leak down on the cylinders is practically non existent due to the fact the engine was torque plate honed when I rebuilt the engine. My conclusion is that the MAP sensor or the throttle position sensor is faulty and obstructing the timing at idle causing a lean misfire possibly. The computer has not flashed any codes and yes the SES light is operable. There is not many electronics to this engine really and the thing runs to good to have a fuel pressure problem I would think. If you have any suggestions let me know. Im up for any advice.
A D V E R T I S E M E N T S
The truck runs very rough at steady RPM with no load on engine. Cruising down the highway the truck will start cutting out and never goes any further than that but I rebuilt a set of factory throttle body heads and changed the camshaft to a Crower camshaft with a 112 degree lobe separation and not much more lift than the factory cam. The cam is able to maintain proper vacuum at idle and at steady RPM`s. I changed the rocker arms out and put a 1.6 roller rocker on the intake and 1.5 on the exhaust. The truck runs phenomenal when you have your foot in the floor board. Cruising at steady seems to be a problem. The Idle is a little rough due to the nature of the cam. Just a little choppy but not to the point the engine is surging, and throttle response off idle will squall the tires into second. There are no vacuum leaks and the engine has a steady 150 pounds of compression on all 8 cylinders. Leak down on the cylinders is practically non existent due to the fact the engine was torque plate honed when I rebuilt the engine. My conclusion is that the MAP sensor or the throttle position sensor is faulty and obstructing the timing at idle causing a lean misfire possibly. The computer has not flashed any codes and yes the SES light is operable. There is not many electronics to this engine really and the thing runs to good to have a fuel pressure problem I would think. If you have any suggestions let me know. Im up for any advice.
- Clint A., Duncan, OK, US