1 Peter 4:10-11
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70 series (98-00)
S60,V70, XC90, XC70(01-09)
S40, V50, C30, C70 (05-11)
1. Boost pressure sensor
2. MAF sensor
3. Throttle position
3. ETM (throttle module)
ECU looks at throttle input to determine how much power, and consequently boost, is required to meet driver wish.
From there ECU references the TCV duty map to determine how much pressure to block from wastegate so boost can build.
As pressure is blocked to wastegate, boost builds. As boost builds close to target ECU trims TCV duty to allow wastegate to start opening and control boost pressure.
The pretension of the wastegate is an assumed value in ECU to balance TCV duty against.
If wastegate tension is off, the boost control strategy is imbalanced.
If TCV is weak/lazy then boost control strategy is imbalanced.
If there is a leak, then MAF and flow metrics will be imbalanced.
If there is a fault, even without CEL, boost will be limited.
So if you're not seeing boost, first thing is ensure no pending or active faults (even without a CEL)
From there mechanicals must be ensured to be proper. Wastegate pretension, TCV Function, and leak checks.
Lastly logging can be useful. VIDA/DICE is inexpensive and powerful. If you plan on doing more of this (with Volvo models) you will want this tool.
Lastly the smallest things can be problematic, in fact if spark plug gap is too wide it can create boost onset misfire low enough not to set CEL but high enough to create boost imbalance and ECU type 1 intervention.
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