[BlackVert]

I am getting detonation on throttle tip in. After researching it, I suspect that changing the Manifold Volume scalar will solve it.

Here is my theory on the purpose of the Manifold Volume scalar:

The manifold volume scalar is used by the PCM to decide how much of a delay there is between the change in the reading at the MAF and when the air actually hits the cylinders.

I liken it to seeing wind hit a tree 20 feet away but not feeling the wind until 5 seconds later. In this analogy, the tree would be the maf and I would be the cylinders.

The larger the volume, the longer the delay, and the PCM waits until it thinks the increased air flow has hit the cylinders before increasing the pulsewidth.

The smaller the volume, the shorter the delay, so the pcm increases the pulsewidth earlier.

This would explain the behavior people see where decreasing the value of this scalar solves a lean condition on throttle tip-in.

I will try my theory tomorrow by decreasing the value and post back with my findings ...

[broken_joke]

the j4j1 stock values show 5.5 liters and zao 4.125 liters. so would it be safe to say that the cobra r has a shorter runner intake and the cobra has a longer runner intake?

[final5-0]

I fooled around with that scalar a while back

PCM Equivalent of Carb Accelerator Pump ?

Grady

[BlackVert]

yep, the cobra r must have shorter runners.

my tip in pinging is gone when the intake charge is not too hot.

but it is still there after i have been cruising for a while ... the intake charge gets up to 220*!

i need to yank out the egr and get a methanol kit.