Jeep swap no spark!
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Registered User
Joined: Feb 2019
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Jeep swap no spark! Newbie here so sorry if im posting this in the wrong area, I’ve read what seems like every thread on no spark issues but can’t seem to find my issue with spark,
Some details: 2004 5.3 lm4 out of a trailblazer, diy Stand alone harness, e2000 fuel pump and a th350 trans I swapped into my 99 wrangler. The motor gets fuel(58 psi at the rail) and you can smell it after cranking. I’ve replaced the crank sensor checked for power/grounds everywhere. I’m not getting codes with the torque pro app and Bluetooth dongle. I can manipulate sensors and see them change on my tablet so the pcm is communicating with the motor but still have no spark at all.
Only thing I’ve done different is grounded the 3 wires from the back of the head else where. Can this be a big issue? I’ve been chasing this issue for 3 weeks now and im starting to loose sleep over it. Any help will by much appreciated!!
Some details: 2004 5.3 lm4 out of a trailblazer, diy Stand alone harness, e2000 fuel pump and a th350 trans I swapped into my 99 wrangler. The motor gets fuel(58 psi at the rail) and you can smell it after cranking. I’ve replaced the crank sensor checked for power/grounds everywhere. I’m not getting codes with the torque pro app and Bluetooth dongle. I can manipulate sensors and see them change on my tablet so the pcm is communicating with the motor but still have no spark at all.
Only thing I’ve done different is grounded the 3 wires from the back of the head else where. Can this be a big issue? I’ve been chasing this issue for 3 weeks now and im starting to loose sleep over it. Any help will by much appreciated!!
TECH Fanatic
Joined: Sep 2008
Posts: 1,654
Likes: 531
Good grounds are really needed. Battery to the frame. Frame to the engine block. Engine harness to the block.
On one of my LS swaps I didn't have the cam sensor pushed all the way in and it wouldn't start.
Do you have power to the ecm on start and run? Does the fuel pump cycle and them shut off when you turn the key to "on" but not all the way to start?
Can you test the injectors to see if they firing? Same thing with spark?
On one of my LS swaps I didn't have the cam sensor pushed all the way in and it wouldn't start.
Do you have power to the ecm on start and run? Does the fuel pump cycle and them shut off when you turn the key to "on" but not all the way to start?
Can you test the injectors to see if they firing? Same thing with spark?
