Detonation Issue

[240Kuminachu]

It sounds like a fully auto BB gun. Only at full throttle, It wont do it at half throttle. I retarted the timing all sorts of ways, It lessened but its still there. What degree of retard should there be under boost? Is it progressive timing? Also, what else could cause this if the retard'ed ignition doest help. The air/fuel is right on, 93 octane chevron gas, 8:5.1 compression. T25 turbo, stock boost, FMIC.

Suggestions Please.

[msaskin]

I generally retard timing by .75 degree per psi of boost.

~matt

[240Kuminachu]

Thats what I originaly went of off matt but it still does it. I went as far as 10 deg retarted at 5-6psi. Its still doin it.

What about spark plug brands and gap? Or crapy plug wires, would that contribute?

[msaskin]

Thats what I originaly went of off matt but it still does it. I went as far as 10 deg retarted at 5-6psi. Its still doin it.

What about spark plug brands and gap? Or crapy plug wires, would that contribute?

Brand isn't as important until you're finalizing your tune...gap would affect it though. I run .028 and don't have too many ignition issues. As for wires...your car doesn't have spark plug wires (unless you went away from the stock COP setup)

FWIW I'm running about 17 degrees of timing @ 8psi boost on a GT25R and still have WAY more room to go...no knock/backfiring and spool is still wicked slow.

I'd check plug gap / condition first and then go from there.

~matt

[240Kuminachu]

thanks guys, I retuned the timing a little and added some retardedness, (great) under boost, it seems to be doing fine, I think im at 12 deg at 8 psi, some other local nissan guys helped me out.

I had some fun with the car today, I unhooked the wastegate and hit 15 psi for a split second, the piping dint hold up too that too well.

Isnt there a way to up boost by hooking your wastegate to a certain vacume line?

[msaskin]

Nope. To up the boost you need something to act as a restriction in the vaccum line to the wastegate, or to bleed off some of that air.

That's how boost controllers work.

~matt