Engine RPM goes up and down at traffic light

Tiny
ERIC OU
  • MEMBER
  • HONDA ODYSSEY
My van is a 2003. It was running smoothly until two weeks ago after an oil change at a garage. Right after the oil change, when I stopped at a traffic light, the engine rpm's went up and down between 700 rpm's and 900 rpm's. The drive gear (shift) is on drive. If I shift the driving gear to parking or neutral, the engine would run fine. After fifteen minutes of driving, the symptom would go away. I brought the minivan back to the garage. They said there was a vacuum leak and fixed the problem. However, the problem is still there.

I took the minivan to a Honda dealer. At first a mechanic said that he could not find anything wrong. There was no error code. Then he said the air control valve is bad and replaced it. However, the problem did not go anywhere, even worse. Now, no matter long I drive the minivan, the symptom stays on.

But if I turn the steering wheel to either right or left for some degree while the driving gear (shift) is on drive (of course I put my foot on the brake pedal), then the engine would run smoothly.

What could be wrong?

Thanks
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Thursday, December 7th, 2006 AT 3:59 PM

6 Replies

Tiny
BRUCE HUNT
  • EXPERT
I would sense that turning the wheel right or left puts a slight strain on the engine and it must compensate for this by supplying more fuel. I would venture to say that if you apply a bit of gas while sitting there it goes away as well.

What other work has been done to the vehicle recently?
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Thursday, December 7th, 2006 AT 11:42 PM
Tiny
ERIC OU
  • MEMBER
Bruce,

I applied a little gas and let the engine rev go above 1000 rpm's, the problem went away. I did not do anything on the minivan recently.

Thank you.
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Friday, December 8th, 2006 AT 12:22 PM
Tiny
BRUCE HUNT
  • EXPERT
This sounds like a vacuum leak. Check hoses, idle air control valve can be taken off and cleaned. The next thing I would do after the check of the hoses though is to check the cooling system for being full and make sure you purge the air out of the system through the bleeder valve.
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Friday, December 8th, 2006 AT 6:42 PM
Tiny
ERIC OU
  • MEMBER
Bruce,

You are amazing! I checked hoses and found no problems. Then I opened the radiator cap (hope to release some air if any) and put it back. The problem is gone.

By the way, how is that related to the engine rev?

Thanks a lot!
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Saturday, December 9th, 2006 AT 11:13 AM
Tiny
BRUCE HUNT
  • EXPERT
Air gets trapped in the system, little pockets get joined together and a pocket of air does not exactly reflect the temperature of the coolant. The sensors in the engine think it is one temperature but the air has another temperature and they send mixed signals to the computer. Then the computer requests more gas, then less gas, etc. Confusion!
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Saturday, December 9th, 2006 AT 4:55 PM
Tiny
AUBIERPH
  • MEMBER
I just wanted thank you for this information and help. My wife was dropping several neighborhood children at school and the odyssey suddenly lurched forward. Fortunately, my wife successfully stopped the minivan with, what else, the brake, but not after sending a panic through all of the passengers. My wife arrived home in a panic, saying she barely made it home with van lurching and revving. After two hours of web research, I decided to get a new transmission. $3,000.00 to $4,000.00 from Jasper Transmission. Then, a friend said it may be the 'torque converter'. I did another search for 'revving' and stumbled across this information. I went outside, opened the radiator cap, a little bubble escaped like a tiny fart. I restarted the car and voila! The revving disappeared! Thank you so very much! Kenneth Garrison, Huntsville, Al.
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Monday, October 13th, 2014 AT 8:26 AM

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