Thread: 2004 L26 Grand Prix GT - Wild Cylinder Skewing from Factory (Discussion)

So after some head scratching, digging and research I have determined that in 2004, 2005 GM skewed the NA vehicles with the following.

This only applies to Naturally Aspirated L26 equipped Grand Prixs.


I am searching for the reason behind this. My only guess is that they determined the volume of air to be different per cylinder and adjusted the fueling to match.

EDIT: Yes, Bio - good point, The rear manifold does infact flows better than front.
** would this mean more fuel required in the front to combat KR or less fuel since less flow ?
( i would guess more fuel)





Can we get a discussion going here?

I have never seen individual cylinder skewing from STOCK before.

I have confirmed with multiple 2004 and one 2005 GP stock bin files.

http://www.grandprixforums.net/lf-st...tml#post739989


When I got turbo, I will be definitely setting them all to 100% and then making adjustments based on plug readings and whatnot.

well, really the rear manifold flows better than the front, so isnt that skew backwards from what it should be?

Update: Here is the 2005 Skewing...

Originally Posted by Bio248

well, really the rear manifold flows better than the front, so isnt that skew backwards from what it should be?

Bio - you are right, This is a fact that the rear manifold flows better than the front.

All maps i have seen list the cylinders in the same order (3,2,1,6,5,4) I'd have a hard time believing this would be incorrect. - Tho I spose it is possible






I'm no wind tunnel or flow tester so i'm not sure which ports would see more air.

If anyone wants to take a crack at it, I have listed the image above with the cylinder ports numbered.