Boost Issue

[mr gsr]

Keep us posted...

I have seen the same overboost on a number of cars myself... Everyone seems to think its normal with factory boost control.

[Wenier]

Have you considered replacing the wastegate actuator since you have a larger flapper on it.

[mr gsr]

I have a 12psi actuator and the FG housing with the bigger flapper... Overboost only occurs during gear changes on the zf box... Could be that its the timing retard which causes this?

[DesFlurane]

Don't think it can be.

You can see the ignition advance going from 8 or 9 to -13 or 14 then back to 8 or 9 within 0.something of a sec.

What should the manifold pressure be in relation to the read boost pressure?

Edit

Boost + atmospheric pressure = manifold pressue

Back to the drawing board.

Edited 25/01/10 03:57 AM by DesFlurane

[IH8TOADS]

Boost plus atmospheric pressure does not equal manifold pressure.

Boost = (manifold pressure - barometric pressure) / 2.04

Remember the MAP sensor output is in inches of murcury.

IMO I would plug the actuator line directly into the compressor housing and do a log with just wastegate spring tension.... graph boost against time and see if you are spiking on the change. You will know for sure if you have a mechanical issue that way.

I also notice you're timing is similar at boost levels of ~12psi and above. I doubt your tuner has re-calibrated the normaliser tables so that you have a higher top load point, meaning you can add timing in the 10 - 14psi (~1.6 - 2.0 load) area.

edit spelling!

Edited 25/01/10 07:36 AM by IH8TOADS

[DesFlurane]

My MAP is in PSI. Or so it says on my datalogger.

Atmos press, 14.7 or there abouts + boost press = MAP

It is correct in all the logs.

Edited 25/01/10 10:36 AM by DesFlurane