No low end performance. Sluggish. 5.3
06-20-2016, 11:34 AM
#1
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No low end performance. Sluggish. 5.3 Hey guys. Need a little help. Installed a 5.3 into a jeep. Engine was rebuilt somewhere else and used an aftermarket mild cam. We sent off the harness and Ecm to Jims performance with spec sheet. . Engine is early 03 flex fuel but drive by cable.The problem is it is a slug. Absolutely no power at low rpms especially. It is carrying 55 lbs of pressure. Second ecm installed. No change. It doesn't have any codes and isn't an electrical miss. Its just an absolute dog. It feels like the timing is way low. Even when it fires up it doesn't just jump to life. It just kinda starts running. Is it possible for a cam sensor to cause this. Or can an aftermarket cam be ground incorrectly? Any ideas? I suppose the timing gear could be off a tooth. Anybody got anything I'm just overlooking. It was taken to Justune in Kansas City. A well known tuner in this area. He looked at it for three hours and is stumped as well. ???????
06-22-2016, 12:02 PM
#2
If justune couldn't figure it out, I would definitely suspect cam timing. Either off a tooth or the cam was ground wrong. Pull it apart and put a degree wheel on it.
Also, are there any restrictions on the intake or exhaust side? Are you getting wide open throttle?
Also, are there any restrictions on the intake or exhaust side? Are you getting wide open throttle?
06-22-2016, 01:04 PM
#3
TECH Apprentice
Hey guys. Need a little help. Installed a 5.3 into a jeep. Engine was rebuilt somewhere else and used an aftermarket mild cam. We sent off the harness and Ecm to Jims performance with spec sheet. . Engine is early 03 flex fuel but drive by cable.The problem is it is a slug. Absolutely no power at low rpms especially. It is carrying 55 lbs of pressure. Second ecm installed. No change. It doesn't have any codes and isn't an electrical miss. Its just an absolute dog. It feels like the timing is way low. Even when it fires up it doesn't just jump to life. It just kinda starts running. Is it possible for a cam sensor to cause this. Or can an aftermarket cam be ground incorrectly? Any ideas? I suppose the timing gear could be off a tooth. Anybody got anything I'm just overlooking. It was taken to Justune in Kansas City. A well known tuner in this area. He looked at it for three hours and is stumped as well. ???????