QuestionQUESTION: What sensors would most likely give an erroneous signal to enrich fuel mixture? Operates normally with cold engine/rich operation occurs when engine reaches normal operating temperature.
ANSWER: Have you checked for any diagnostic trouble codes? There are a couple of possibilities, the ECU coolant temp sensor,a cold start injector that is leaking, a fuel injector that's leaking or even an air intake leak, is it a 4cylinder or V-6 engine?
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QUESTION: (4 cyl.with only 100K miles) My scanner will not work on models prior to 1996, so I may need to buy one specific to this vehicle, though have had NO "Check Engine" lights. I was guessing perhaps coolant temp sensor & O2 sensor a good place to start (both factory original). Has always had the best of dealer maintenance, but am tired of every visit being $350 or more! Have an A&P license for aircraft, but these new cars are a different kind of challenge.
AnswerYes you are right, some of the new hybrid vehicles have more onboard computer systems than the space shuttle. There is an easier way to retreive diagnostic trouble codes that do not require a scantool and the 1990 model has the OBD I diagnostic system which does not require the use of the scantool, find the diagnostic connector under the hood, it should be located near the battery, it has a cover on it, open the cover and identify the terminals TE1+E1, put a jumper wire between the two terminals, with they key ON, the check engine light will flash, it will give the trouble code, it will be a two digit code with a pause in between code numbers, for instance if there is a code 21 it will be 2 blinks and then 1, if there is more than one code there is a pause and then another code will follow. Some faults will not set a code on these early systems.
