Engine Control - TPS Information and Specifications
87chevy20Number: 88-55
Section: 6E
Date: Oct., 1987
Subject: TPS INFORMATION AND SPECIFICATIONS
Model and Year: 1985-88 CAVALIER, CAMARO, CELEBRITY, BERETTA, CORSICA WITH 2.8L V6 (VIN CODES W, S)
TO: ALL CHEVROLET DEALERS
Some 1985 through 1987 Service Manual 6E3 Sections covering
the 2.8L V6 PFI engines do not include information on the
ability of the ECM to auto-zero throttle position sensor
(TPS) reference voltage. Auto-zero can be described as the
ability of the ECM to determine a closed throttle position
any time TPS voltage is within a specified range (see chart
below). As long as the TPS reference voltage is within
that range, the system will function properly. This
capability is found on all 2.8L PFI engines (VIN Codes W, S).
When checking TPS output voltage at closed throttle, there are different specifications for the different 2.8L V6 applications. "Scan" tools having the ability to also read the throttle valve angle should read 0% when the throttle valve is closed. Do NOT adjust the TPS on engines (VIN Codes W and S) if the voltage is within the specified range and throttle valve angle read 0%.