I just installed a 5.3 shortblock out of a 04 Tahoe with milled. 040 98 ls1 heads into my 98z28. I also installed a ls6 cam. Put motor in and it will not run. It cranks and cranks. Like its out of time. I have good fuel pressure,injector pulse and spark. I'm stumped any ideas? All help and advice is greatly appropriated.

 

Are you throwing any codes?

 

Nope. Checked that too.

 

check plugs for water/oil.........

 

Are your coils wires on correct and not flipped around? Do you need diagram?

 

Does the 04 5.3 have the front or rear cam sensor? That could be your problem. The 98Z28 was a rear can sensor.

 

I got mad and left the shop before I got a chance to pull a plug but they were brand new and put them in when motor was out. Don't think I have coils backwards since its an 98 and they mount individually to valvecover. And yes the 5.3 I have does have the rear cam sensor.

 

I'm assuming you have a tune for the extremely lower compression, less cubic inches and a larger cam? You changed so many variables, it doesn't surprise me that it doesn't start.

 

No factory tune. I've seen on the board many guys that run a 5.3 on factory tune. I could understand it not running well but id think it'd start. I've installed huge cams n ported heads and had them run on a factory tune.

 

You can have the harnesses turned around they have to go a certain way

 

If you still have the 98pcm thus is the coil diagram for it



.1. PPL
3. LT BLU
5. BRN
7. DK GRN


2. RED
4. DK GRN/WHT
6. BRN/WHT
8. LT BLU/WHT

 

I still have the 98 pcm. Guess I don't understand how I could have the harness wrong if it plugs in and the lock fits?

 

Did you unhook the harness from the coils at all? If so it might be your problem, if you unhook all four coils from the harness your able to turn it around and it hooks up the same, but on the 98s the wires on the harness has to go to a certain coil... when you get back to the shop check the wires with the diagram above and see if it matches up.. you get what I'm saying?

 

Ok I get it now. I only unhooked them from the one bulk connecter on each side tho.

 

Oh ok

 

I installed a 3.5L in a Montana that originally had a 3.4L and it would'nt start . It ended up being the lifters somehow were too full of oil or something like that because the valves were staying just a few thous open . So I pushed on the rockers by hand to open each valve 1 by 1 and after a cpl times doing that They closed and it started and ran a little rough 4 a few minutes eventually returning to normal . Something I had never seen or heard of before

 

it shows the cam sensor is a different part number from a 04 tahoe to a 98 ls1. ive tried both sensors, any possibility its a cam sensor problem?