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Help! Hammerhead issues

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Hey Guys

i have an 06 23lsv with the hammerhead. 340 hrs on the motor. 
The engine is hesitating under load and at higher rpm approx 4800 when not under load. It will sometimes pop through the intake if pushed when it starts to hesitate and the check engine message will appear.  I have changed fuel filter, plugs, cap and rotor, sensor in the distributor, Coil module, plug wires, and fuel pressure regulator. It throws a crank position sensor code so that has also been changed. There was no wear on the crank sensor. Even with the new sensor it still throws the code as well as the check engine message. Fuel pressure shows 60-70 psi on a gauge and is jumpy. It was the same with the old pressure regulator. 

Any idea what to look for next?


Edited by doug44deuce
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I would recommend you check the engine cam angle.  It is basically used to help set the correct ignition timing and is adjusted by rotating the HVS ( High Voltage Switch / distributer) kind of like how a standard distributer ignition system is timed.  On engines with the MEFI5 ECM, it should be 700-710 degrees at 1200-1500 RPM.  You will need a laptop with the Rinda Diacom software, the diagnostic cable, and the CAN adaptor to do this, or take it to a shop that has that setup.

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The mechanic who read the crank sensor code for me this morning mentioned he thought the cane angle was incorrect and was going to look into it and will be back Wednesday. I remember him saying it was at 500. I’m not sure what rpm that was at. Hope/pray that could be the problem🤞🏻. Thanks for the info. I’ll keep you posted. 

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The cam angle should not be checked or adjusted below 1200 RPMs.

Due to the lack of clearance between the HVS cap and the intake plenum cover on some engines, occasionally the HVS needs to be reclocked to get the correct cam angle adjustment.  That means removing the HVS, turning it to the next gear tooth on the cam, then reinstalling it so the cam angle can be adjusted correctly.

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1 hour ago, justgary said:

Is it making a squeaking or chirping noise?  It may have an intake leak.

Or a chipmunk.  :)  (Sorry - I could not help myself.  The intake leak suggestion is a good one!)

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No vacuum leaks. No squeaks at all. 
it sounds good and strong until it’s loaded then stutters and pops. 

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