From: Michael Gerard [michael@thepatio.net] Sent: Thursday, February 10, 2000 8:56 PM To: 928 Subject: [928] Re: Top speed 140 this morning. Not good. At 02:37 PM 2/10/2000 , you wrote: >This morning on the way to Sears Point Raceway, CA I had Highway 37 all to >myself. The car pulls pretty strong in third gear. At about 125 - 130 MPH >the transmission shifts into 4th and the RPM's drop to 4500. But, No >power.The engine sat their and only took me up to 140 Mph. It felt rather >pathetic so I continued down to cruising speed. Erik - It may simply be that the engine was starved for AIR. Two easy things to check: 1) (unlikely) the air filter... if it is in any way clogged up you're going to feel it at the very low end, and the very high end. 2) (very possible) the resonator flap, affectionately known as the "flappy". The 32 valve engines have a dual air path... at around 4,000 rpm a flap at the top of the plenum opens up and creates a longer air path for the intake. Checking the free movement of the flap is simple: pop off the black rubber cap on the plenum, grip the spindle with lineman's pliers and turn to counter clockwise. If it moves freely without sticking then you know that past is likely functional. Put a piece of electrical tape on the top of the now exposed spindle such that it sticks up like a flag and when you start the engine you'll be able to see if the spindle turns. It should turn 45 degrees on engine start and then immediately close... rev the engine slowly to around 4500 rpm and you should see the spindle/flag/tape turn 90 degrees and remain open until the rpms fall below 4000. the following is from Fred O'Rourke... If your flap does not work and you know the flap is free to move then there are three main possibilities: 1. The solenoid actuated valve is naff. 2. The actuator on the underside of the manifold is naff. 3. Your vacuum system is naff. [ed. note: I still have no idea what "naff" is. Naff said.] To diagnose: 1. Solenoid valve [just in front and below the inlet manifold]: Disconnect the plug. Apply 12 volts over the two terminals on the valve. You should hear the solenoid engage and disengage. You can also disconnect the vacuum lines and when the solenoid is open you should be able to "blow through" the valve. If the tests are positive move on. When the car starts the system should transiently put 12 volts on the solenoid terminals for a second or so. You can try to measure this on the connector terminals. If the solenoid valve is functioning O.K. move on. 2. Disconnect the vacuum line that runs from the solenoid valve and disappears into the front of the inlet manifold. If you apply very light pressure to pull the line towards you, you should feel resistance from where it connects to the flap actuator. If there is no resistance the vacuum line has come away and it will pull straight out [ I stress very light resistance!!]. If you suck on the free end of this line you should be able to actuate the flap. If you cannot move the flap this way then the problem is with the actuator under the inlet manifold or the vacuum line has disconnected. - michael 1988 928 S4 A/T RMB -> Daily Driver see at... Cassisrot Metallic/Burg.-> http://members.rennlist.org/michael 928 OC Charter Member -> http://www.928oc.org PCA NOR Volunteers Coordinator 928 OC International Convention -----> http://www.928OC-IC.com July 13 - 16, 2000 Wichita, Kansas BE THERE!