89 Prelude won't start regularly, stalls

1989 HONDA PRELUDE
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KUSHLA
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89 Honda Prelude with 200 000 miles.
My idle varies from day to day or even while I am driving, from as low as 400rpm or 700rpm to 900, 1100 or 15000rpm.
Regularly the car won't start, it has stalled when stopping at a stoplight, and once when going over a speedbump at a low speed.
Under advice from mechanics I have recently replaced fuel pump, ignition coil, ignition switch, air and fuel filters, distributor cap and wires (tune-up)...
Most recently it was tested to have spark and fuel pressure at the time that it stalled.
Check engine light indicates MAP sensor is faulty.
Tomorrow I will test the MAP sensor and also try to plug in a computer from a friend's 89 Prelude.
Any other ideas on what could be the problem?
Dec 9, 2006 at 6:44 PM
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BRUCE HUNT
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I think I will hold off until you repost with results of the activities you have planned. Good luck!
Dec 9, 2006 at 8:38 PM
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KUSHLA
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The MAP sensor is fine.
Dec 17, 2006 at 2:01 PM
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BRUCE HUNT
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Did you plug in the other ECU? Now let me ask if you have a crank or camshaft sensor on the vehicle? I am not given access to the schematics on the vehicle yet and can't look that up. But, I suspect you have one or both of these. They allow spark to continue but the problem they can cause by failure is that the timing of the spark is not correct. It is so far out of whack that the car fails to start. Ever had a headlight that works and then doesn't work. The next time is works it just keeps working. Won't work the next time and then she works again for awhile. Welcome to the age of electronics! You could have a sensor that is failing, does not trip the check engine light and will take a while before it completely gives out.

Check your maintenance manual for these sensors and the tests they show for testing.
Dec 18, 2006 at 8:33 AM
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KUSHLA
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Wow. Thank you for your advice! I will follow it and let you know.
Dec 18, 2006 at 10:54 PM
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KUSHLA
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The MAP sensor tested perfect, and the car had the same stalling problem after installing a different computer (from another 1989 Prelude Si).

Do you have any other ideas?

With so much gratitude for your help,
Kushla
Jan 4, 2007 at 7:19 PM
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BRUCE HUNT
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Would you say that the engine surges at idle? Have you had any head work done on the engine or intake manifold taken off?
Jan 5, 2007 at 12:11 AM
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