1999 Honda Odyssey Accelerates and desaccelerates in Parkin

106,000 MILES • 6 CYL • FWD • AUTOMATIC
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JMLOPEZ
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  • 2 POSTS
When I start the engine it accelerates an desaccelerates repetdly from 1000rmp to 2000rpm
May 29, 2008 at 11:24 AM
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KHLOW2008
  • ✓Experienced Mechanic
  • 41,812 POSTS
Hi jmlopez,

The engine idling speed is too high due to vacumn leakage or a loosened idle adjusting screw.

Check the ISC and the coolant hoses to it.

Low coolant level will also cause the problem as the ISC is not getting the correct temp.
May 31, 2008 at 5:30 PM
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JMLOPEZ
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  • 2 POSTS
Hi KHLow2008,
Thank you. I verify the ISC and the coolant level or leaks and found everything OK.

Today I scanned my Honda and pulled code P0505. Any ideas appreciated.
Jun 4, 2008 at 3:17 PM
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KHLOW2008
  • ✓Experienced Mechanic
  • 41,812 POSTS
Hi jmlopez,

P0505 is a malfunctioning ISC.

How did you verify that the ISC is ok?

For this model if the ISC valve is short circuited and replacement of a new ISC still show the P0505 code, then you need to replace the ECM as well as the circuit in the ECM is damaged.
Jun 4, 2008 at 11:25 PM
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