Intake Manifold Pressure

[oneshot]

Anybody got any ideas on the "normal" values for the Intake Manifold Pressure under various conditions i.e. idling, WOT etc.

Just done a run with an OBD scan on and just want to check the figures.

[peter_england99]

This isn't easy to answer.

The boost readings vary depending on the ECU installed in your car (standard or sport 350 or one of the customised 'red race' upgrades). Even with the same ECU software you see different boost value as the ECU takes inlet temperate, vehicle load, current gear selected and vehicle speed (probably several other sensor reading as well) into acount before deciding what boost are permitted.

Officially on a standard set up when the inlet temperature is cool enough and the vehicle is in 5th Gear and the car is travelling over 130mph then the max boost is 0.75bar.

I noticed on my car how much of the time the boost was in fact a vacuum (less than 1bar absolute pressure) as the pistons were sucking in more air than the turbos were supplying.

Markus and Johan are the guys on this forum who know what really happens in the ECU. Maybe they could elaborate.

Regards,

Peter.

.

Anybody got any ideas on the "normal" values for the Intake Manifold Pressure under various conditions i.e. idling, WOT etc.

Just done a run with an OBD scan on and just want to check the figures.

[Backmarker]

Dave,

Are these not in the Service Manual?

Surely the "default" values must be somewhere.

Presume you're running the Sport 350 ECU.

Graham.

[oneshot]

Hope so since the car is a Sport 350

[Paula&Marcus]

Look David,

here is a diagram/graph that shows you the theorethical boost curves rpm v. boost with TSP=100% (= full throttle):

The maximum shown is 0.75 bar atm. Of course with TPS<100% the boost will be much lower and may also be negative (= MAP < 1 bar atm)

Cheers

Marcus

PS: Could you put your OBD data into an excel-file and and do a nice graph ... like the one above ?

Anybody got any ideas on the "normal" values for the Intake Manifold Pressure under various conditions i.e. idling, WOT etc.

Just done a run with an OBD scan on and just want to check the figures.

Edited April 25, 2007 by Paula&Marcus