Hello guys and gals. Yeah I know the title has been beaten to death but I've researched and read and researched and read some more. This is my last resort.

I have a 2004 LQ4 out of a 2500 truck that won't start. I rebuilt it using an LS swap book. Followed it all the way through. I just cant for the life of me get this thing to run.

So this is what I have and what I've checked. 04' 6.0L LQ4 that I installed flat top pistons, stage 1 truck cam, LS7/9 springs/lifters, bronze trunions, factory 317 heads and pushrods, I have a 08' truck intake manifold to a 3 bolt DBW throttle body I have ev6 style injectors that are a higher flow rate injector.

I have a 150tunes.com harness with a programmed PCM from the same place. So VATS is deleted as well as emissions and injectors tuned etc.

I have 55-60psi for fuel while cranking, I have spark tested each spark plug and I have spark while cranking. I visually verified each injector was spraying fuel as it should while cranking. I have good compression in each cylinder. My TAC module controls the throttle body plate as it should. I can hear my fuel pump activate as well as the TB plate move when keyed on. My harness is wired, to a 12v hot source for on and ignition.

I have ground from the harness going to my body and to the driver side head. Grounds from my battery directly to passenger side head. A grounding strap from head to body. A ground from battery to frame and then frame to engine block.

Timing has been checked about 3 times now. Since that threw me for a loop with TDC and the dots with firing order etc. I made sure #1 was TDC using whistle tool. Loosened the valves and spun the cam shaft around to have the alignment dowl at the 3 o'clock position and had the camshaft sprocket dot lined up at the 6 o'clock position, directly to the crankshaft sprocket dot. Tightened back down the valves and spun the motor to find the TDC on #1 was already happening 180° out. (Both dots at 12 o'clock position).

Previously the motor cranked and didn't start. I found out my TAC was the wrong model for the year. Ordered a new one and now it works the TB plate. Previously it threw crank shaft codes P0335/6, and several TB codes. I replaced the TB and both cam and crank sensors. Now it doesn't throw any codes but it still won't start.

Cranks great but no start. Any suggestions on where to go from here? Thank you!

 

Have you replaced your MAF?

 

No I haven't. All my sensors are brand new. I know some can be bad right out of the box, but...

 

If your MAF isn't plugged in car won't start, I'd make sure it is.

Try shooting some starter fluid in that **** and see if it turns on

Edit: Be careful not to burn your eyebrows

 

Does it sputter like it wants to start?

Verify cam timing with a degree wheel.

 

MAF is plugged in to a temporary air duct. I've sprayed starting fluid in it previously with no luck.

It cranks and acts like it wants to starts, all I have is headers right now so it pops. When I give it light throttle while cranking it cranks faster and sounds like it's almost there.

 

Battery good?
Maybe give it harder throttle.

 

Have you visually verified that the fuel pump is pumping fuel? I know this sounds trivial but I just get a feeling this is a fueling issue.

What about your fuel pressure regulator?

 

Battery is good. I've done WOT and still no start.

Fuel pump is brand new and in tank. I have a corvette regulator that's functioning as it should. Fuel pump will prime with key turn to on position.

 

Okay so moving away from fuel and back to sensors

Crank relearn? I think that causes these symptoms. Gotta do one of those may e

 

I will try and locate a scanninscanning as that function. I had one available but it wanted The motor to run And reach a certain temp to do so. Of course that couldn't happen.

 

Idk what a scanninscanner is but I was pretty sure you could do a crank relearn without motor running

Maybe I’m wrong though

 

sorry. Phone decided to write that. I had a snap on scanner tool

 

Probably not the type of problem that [mr.spock]scanning[/mr.spock] will help with.

What's the lifter preload set to?

 

Did you confirm fuel injector pressure? just because the injectors have fuel coming through them does not mean that the pressure is correct.

 

He said 55-60psi while cranking.

You off your adderall this week? You're posting like crazy

 

Bored as fuuuuck at work.

Although he did say 55-60 psi while cranking that doesn't mean the injectors are doing that thing when you activate them. I can't remember are they supposed to hold pressure or drop pressure? When you cycle the injectors with the scan tool I mean. I had some injector issues on my truck and I think they weren't holding pressure but I can't remember.

Maybe it is a vacuum port you forgot to plug up lol

Life of an IT guy though. Basically like a fireman, sit around all day and then go do something for a little and then back to sitting around.

 

I bought a new harness once and the plug at the MAP sensor was wired backwards…from the factory. Car wouldn’t start for anything. Never assume anything here when dealing with new parts.

 

What's this thing going in or did I overlook it?

 

Well I believe I found out what the problem was. I'm still throwing codes but it will start and run to some degree.

With talking to the harness company, he asked me if I had ever had the coil packs off. And how they were wired. I told him I bought new connection harness for them and he suggested the harness may be on wrong. Sure enough. I swapped the plugs around on the coils and she fired up!!

I knew it was going to something stupid.

The motors going in a 73' Scout II for a crawler project. Almost done!