1994-2002 [Subscribe to Daily Digest] |
The intercooler makes the charge air densoity higher, so there is more oxegen to react with fuel in the cylinders. The power variation between summer and winter is a dramatic indicator of this effect.
At hight flow rates the IC also creates a pressure drop and I talked about that yesterday. So the IC does not increase boost pressure, it creates a pressure drop.
Ypu probaby have the MBC pressure sourced frm the compressor housing hose barb. This means that the MBC trys to maintain pressure at this point. So the engine sees this pressure less the pressure drops fron the IC and pipes. This is whay your boost indicator shows pressure dropping as the rpms go up.
The ECU used the MAP, manifold absolute pressure sensor to measure pressure, at the throttle body. It has a small hose to the throtle body. The MAP is small, and bolts to the underside of the RH shock tower brace black pipe/tube. It has a ground and +5VDC from the ECU and a third wire goes back to the ECU with a signal that varies with pressure. The ECU also monitores the intake air temp sensor in the throtle body trnnsition casting to determine the air density. It then calulates the amount of fuel to inject to maitain the target air-fuel mixture.
The ECU attemps to control the amount of boost pressure with a separate function. It odes not comapre teh achieve boost with the desired boost. Amother part of the ECU will map the fule requirements to whatever boost pressure is presented, but will do a fule cut if the boost pressure exceeds a bit over 15 psi. 1.1bar is the number I think. So the MBC forcefeeds the ECU and it works well up to the fule cut.
The MBC has some shortfalls, especially connected as your probably is. Any boost controller really should have its pressure reference taken at the throttle body or manifold. But that creates problems with greater pressure overshoot with the MBC. A connection soon after the IC core is better, keeping in mind that the MBC hoses should also be short.
posted by 209.172.2...
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
 |
 |
 |
 |
 |
