1991 Toyota Supra Repair and Maintenance
A guide to problems, costs, maintenance and repair for your 1991 Toyota Supra
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1991 Toyota Supra ProblemsCheck Engine Light Due to Restricted EGR System
The EGR System tends to get restricted or blocked with carbon after 100,000- 125,000 miles which will cause an emissions test failure for NOX. If the EGR system is equipped with an EGR temperature sensor it will trigger a Check Engine Light for improper EGR flow. The repair is to clean out the EGR passages and the EGR Temperature sensor. Our technicians tell this repair is pretty straight forward and takes about 1-1.5 hours. It is also wise to verify the EGR system components i.e. the Transducer, EGR Valve and VSV Solenoid at this time.
Over the time the exhaust gas recirculation (EGR) system may become plugged with debris, the oxygen sensor may also be getting slow or 'lazy' around this time. When servicing or cleaning the EGR system, it is a good idea to replace the oxygen sensor because it works in tandem with the EGR system.
At higher mileages, (125,000-150,000) the automatic transmission may not shift correctly. This can be caused by the throttle position sensor being out of adjustment or a shift solenoid needing to be replaced. Typically the transmission does not need to be completely overhauled.