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What does pulsating engine mean?

Posted by CatherineT (My Page) on
Fri, Oct 7, 05 at 7:53

Hi all,
About 6 weeks ago, when I took my Honda Odyssey in for it's routine service, I mentioned to the guy that I had started hearing my engine sort of pulsating (fast, slow, fast, slow). He asked if I could see the speedometer arrow pulsating with it and I said a little. Afterwards, he said it wasn't a problem. Now it's getting more severe. What does this mean is happening, and will it be expensive to fix? Does it hurt to drive with it like this? Does it use up more gas, because I've noticed a 3-4 mpg decrease in my fuel mileage. I'm very happy with the service at this Honda place, so I hope I can trust that he knew what he was talking about. Maybe he knew it would get worse without hurting the engine, and we could fix it with my next servicing. Thanks.

Follow-Up Postings:

RE: What does pulsating engine mean?

Does the pulsating happen only when the engine is under load, when you are accelerating, or climbing a hill? Or, does the pulsating happen continually when the engine is running, including when the engine is idling at a stop light?

RE: What does pulsating engine mean?

It seems to be JUST when it's idling.

RE: What does pulsating engine mean?

There is definitely something wrong, but with the fluctuating idle speed and more importantly, the MPG drop. You may have to find a better dealer who can handle these more complex problems.
Have all the sensors checked out and also the alternator.
Computer controlled vehicles are voltage sensitive - this should, with a good regulator, vary very little..

BTW, you are wise to be recording your MPG...

RE: What does pulsating engine mean?

Thanks earthworm,
This is a really great service department at a Honda dealership. They are always very good and honest and competent. The guy I told was the manager. Is it possible he knows that I bring it in every 3500 miles, and thought it could wait until the next time? I'm very perceptive about things....actually, I'm TOO perceptive, and I notice changes long before most people. Maybe it was too subtle at that point, to check it all out. I'm due to take it back in about 6 weeks. Could I hurt anything by driving with it this way, and might the car poop out on me while I'm out with it? I have loved this Honda van, and have never had any problems with it that weren't handled at it's normal servicing. It's at about 93,000 miles, and everything has been covered so far on it. A great car and a great service department!

RE: What does pulsating engine mean?

Catherine T. :

If the engine, at idle, momemtarily drops speed, and then recovers, it's probably the Air Conditioner pump kicking in. The air conditioner pump is active when the cooling position, or cooling with re-heat, are selected, or when in the defrost mode. Maybe the A/C was turned on and forgotten. That would explain a drop in fuel mileage of about 2 miles per gallon.

At low speed, say 20 to 30 miles per hour, sometimes the driver can feel the A/C compressor turning on and off.

Check the settings of your A/C controls. This may explain what you are experiencing.

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