1995 850T Adjusted turbo waste gate and wow!

[mecheng]

Detonation is prevented by retarding the timing not advancing it. If the engine detects knock it retards it due to low octane fuel or excessive heat. Too much boost = too much heat which can cause detonation.

[850TurboTurtle]

Does anyone know of a tutorial online that shows exactly how to check the boost and get it at factory spec, so I know I'm safely within my 2 full turns?

[j-dawg]

Enriching the mix and retarding spark are ways to deal with detonation, and not really the causes of the problem.

The engine control system provides as much boost as it reliably can at each engine speed, and that's why the boost control solenoid and that wastegate actuator. As a result, the bottom end on these engines is solid: valves burn, rear main seals blow out, heater cores pop and head gaskets crack, but nobody bends a rod in a T5 motor unless he plays with boost.

The way aftermarket tunes all claim to improve power at the low end suggests that there's a bunch of wiggle room in low end boost, but the cost is eating into the generous margin Volvo set. It's stepping out of the safe zone and into the probably-safe zone. You might even be as far down as the maybe-safe zone if you don't know that the thing's never been fiddled with in the past. That's why I'd grab a gauge and check where your wastegate is opening.