1990 Toyota Corolla Base, AutomaticFACTORY OEM SERVICE PROCEDURE

Dashpot Control System Test

  1. Engine must be at normal operating temperature. Check idle speed and adjust, if necessary. Remove cap, filter and separator from dashpot.
  2. Start engine. Maintain engine speed at specified testing RPM. See DASHPOT TESTING RPM  table. Plug the Vacuum Transmitting Valve (VTV) hole with your finger.
  3. Release throttle. Dashpot should be extended and dashpot setting RPM should be as specified. See DASHPOT TESTING RPM  table. If idle speed is incorrect, adjust dashpot.
  4. To check VTV operation, run engine at dashpot testing RPM for a few seconds. Plug the VTV hole with your finger. Release throttle. Uncover plugged hole. Engine should return to idle in about one second.
  5. Install dashpot separator, filter and cap. Install filter with coarser surface facing outward.
DASHPOT TESTING RPM

Application Testing RPM (1) Dashpot Setting RPM
2WD 4A-GE 2500 1800
4WD 4A-FE
Auto. Trans. 3500 2200
Man. Trans. 3500 1800
(1) With cooling fan off.
Fig 1: Exploded View of Dashpot
G118991Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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Stop DIY work and contact a certified mechanic immediately if any of the following apply:

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  • • The engine overheats, stalls repeatedly, or misfires under load.
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