2005 Silverado New Built LQ4 No start

[2005 silverado]

Just did a standard rebuild, rings, bearings, lifters, gaskets, and had a valve job done. Also has a xr281 comp cam, with pac 1518's and 7.350 push rods.

All grounds are good, I have Fuel, Spark, and compression, its firing in overlap instead of compression.

The tunes i have tried are a stock 6.0 4l80e tune with the same OS, and the tune i had in the truck when i had the 4.8 and turbo.

Also other weird thing is i have to open the passenger door to get the interior lights to shut off after i turn the key off, it used to be the drivers door.

Any ideas would help.

Thanks Dustin

EDIT- I have checked the cam, its dot to dot.

[joecar]

Did you accidentally swap the left and right coil assembly connectors...?

Does the cam have a front or rear reluctor...?

When you laid the new and old cams next to each other, did the lobes and reluctor match up...?


You got some other connectors swapped left/right.

[2005 silverado]

Coil connectors cannot be installed wrong, harness layout doesnt allow.

Rear reluctor.

From memory they were the same.

[joecar]

If the cam sensor signal is inverted then the PCM would fire on the wrong phase (overlap)... was the cam wiring modified...?

[joecar]

When the PCM does not receive a cam sensor signal it tries to fire on each phase until it gets the correct crank acceleration (and would throw a cam sensor DTC).

[2005 silverado]

I only have a crank relearn code.

No wiring had been modified.

Is there any way to see what the cam signal is reading to verify this? Or is there a way to reverse this and see if it is what wrong? Say if the cam timing tabs where wrong.

[joecar]

( crank relearn can't be done until the engine is running )

One way to see the cam/crank signals is to find someone who has an automotive lab style oscilloscope...

or, you could try re-pinning the cam sensor wires to see what happens (if you now get a cam sensor code, then it was previously correct).

[joecar]

How did you determine that the PCM is firing the spark plugs on overlap rather than compression...?

[64camino]

Engine will still fire even without cam sensor. It will just crank longer (usually 4 full revolutions). Your positive the two little grounds on the backs of the heads are good? pull on them to make sure their not elastic feeling(broken inside). It will not fire without those two. oh, and put gas in it:moon1:

[2005 silverado]

joecar: I pulled number 1 plug out of the head and let it fire out of the cylinder while watching what the valve train was doing.

64camino: I have checked all the grounds, it is firing just not correctly.

[64camino]

Check the crank sensor, make sure there is no metal on it, and it has not been bumped.

[joecar]

Do you have access to a high resolution oscilloscope...?

[2005 silverado]

No i do not.