C70 Me7 boost spikes problem or not?

[thetroublemaker]

I have now got a stack boost gauge installed in the C70.

My boost is set to 10 psi max so stock by the look of things.

If i go WOT from say 1500 - 2000 rpm the boost will build to 12psi approx for about 1 second then drop to a perfect 10 all the way.

If i go WOT from say 2500 - 3000 rpm i will spike up to 13-14psi max again for about 1-2 seconds then drop back to 10 all the way up.

I get a feeling of the car holding back a little when the boost drops back as you would expect.



Is this normal behaviour? Or does this mean perhaps my actuator rod is too short and needs winding out a bit?


I am trying to get everything hunky dory before getting a map loaded on the car

[Dream3r]

Definitely check the actuator and all of the pre throttle body pipes. Having some sort of datalog with timing and requested+boost would also be helpful.

[thetroublemaker]

I have wound the actuator back in 1/2 turn and i now get perfect boosting up to 10, maybe seeing 10.5-11 max and settling with no feeling of holding back

Getting there. Going to change plugs for OE volvo and replace fuel filter then re-re-remap i think

[kmb]

Did you wind in (more wastegate closing force) or wind out (less wastegate closing force) the actuator rod?

I'm assuming you actually reduced the wastegate closing force by winding out, but it's not the way it appears to read?

Thanks for the clarification.

[thetroublemaker]

Sorry.

I wound it OUT lengthening the rod and therefore lowering the waste gate opening pressure.

Apologies for my craptacular English!!

[kmb]

Makes sense now, glad it solved your issues