SC400 startup problem
12-30-15, 06:48 AM
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SC400 startup problem
Car Gurus,
I have been having a problem with my 1992 Sc400 for about 6 months now. When I come out to start the car cold it will not start. It fires and dies immediately. I have to hold the accelerator down to simulate a fast idle until I see the temp sensor move up about (2) ticks before I can very carefully ease off the gas pedal to maintain a very low idle. After the car reaches normal operating temperature, it runs beautifully. After it is warm, if I stop and restart it, I have to feather the gas to prevent it from stalling out. But, once I release the gas pedal all is well and driving is normal without problems. As long as I am driving there are no symptoms at all. It is only when I turn off the engine and restart do I have an issue. It is behaving like the older cars I have worked on which had an anti-stall dashpot that would prevent stalling by easing the idle link back slowly if you suddenly released the gas pedal. Does the SC400 have an equivalent circuit? I have already replaced the IAC with the same result. Any help would be deeply appreciated!!
GeminiII
I have been having a problem with my 1992 Sc400 for about 6 months now. When I come out to start the car cold it will not start. It fires and dies immediately. I have to hold the accelerator down to simulate a fast idle until I see the temp sensor move up about (2) ticks before I can very carefully ease off the gas pedal to maintain a very low idle. After the car reaches normal operating temperature, it runs beautifully. After it is warm, if I stop and restart it, I have to feather the gas to prevent it from stalling out. But, once I release the gas pedal all is well and driving is normal without problems. As long as I am driving there are no symptoms at all. It is only when I turn off the engine and restart do I have an issue. It is behaving like the older cars I have worked on which had an anti-stall dashpot that would prevent stalling by easing the idle link back slowly if you suddenly released the gas pedal. Does the SC400 have an equivalent circuit? I have already replaced the IAC with the same result. Any help would be deeply appreciated!!
GeminiII
12-30-15, 08:51 AM
#2
We were just talking about the dashpot in this thread:
https://www.clublexus.com/forums/per...t-is-this.html
The SC400 does have one. It's on the throttle body, tucked below the TPS. I don't think it would have any anti-stall characteristic on our cars, though. Shouldn't that be the IAC's job?
My guesses as to your problem would be some combination of IAC cleaning and ECU capacitor servicing, with fuel pump ECU being less likely but still worth a test bypass to rule out.
https://www.clublexus.com/forums/per...t-is-this.html
The SC400 does have one. It's on the throttle body, tucked below the TPS. I don't think it would have any anti-stall characteristic on our cars, though. Shouldn't that be the IAC's job?
My guesses as to your problem would be some combination of IAC cleaning and ECU capacitor servicing, with fuel pump ECU being less likely but still worth a test bypass to rule out.
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