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Help - 2004 Honda Accord RPM's Flat-Lining
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MACooke
Novice
Nov 22, 2011, 5:41 PM
Post #1 of 8
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Help - 2004 Honda Accord RPM's Flat-Lining
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Hi. My problem is on the following vehicle:
2004 Honda Accord LX
2.4L 4-cylinder inline, VTEC, w/ 5-speed manual transmission
Approx. 109,000 miles
Yesterday I stopped at the store on my way home from work. When I started the engine when leaving, there was a loud, pronounced whine, high-pitched, and the pitched increased with increasing engine RPM's.
Also, and I do not know if the whining is related to this other problem, but when I was accelerating on a highway on-ramp, when I got up to 4500 RPM's it "flat-lined" so to speak. It hit a wall and I could not get the RPM's above 4500. I got off the highway, parked, then (with transmission in neutral) I slowly brought the RPM's up to 4500 - then it stopped then started bouncing, "voom voom voom", between 4000 and 4500. If I pressed the gas more, the "bouncing" just occurred at a faster rate. It's as if someone took the curve and put a glass ceiling at 4500 - I could not get the RPM's above that.
This was intermittent, on the way home I downshifted and tried to accelerate hard, the RPM's climbed through the 5000's with no effort whatsoever. A minute later it was hitting the glass ceiling again.
Any help will be greatly appreciated. Thanks.
Mitch
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Discretesignals
Ultimate Carjunky
/ Moderator
Nov 22, 2011, 6:45 PM
Post #2 of 8
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Re: Help - 2004 Honda Accord RPM's Flat-Lining
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Did you pinpoint the source of the whining noise?
Does this have any modifications?
Check engine light on?
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Nov 22, 2011, 6:45 PM)
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MACooke
Novice
Nov 22, 2011, 7:01 PM
Post #3 of 8
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Re: Help - 2004 Honda Accord RPM's Flat-Lining
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No modifications, strictly stock. And the check engine light is not on.
I have not pinpointed the source of the whining noise, either.
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Sidom
Veteran
/ Moderator
Nov 22, 2011, 7:18 PM
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Re: Help - 2004 Honda Accord RPM's Flat-Lining
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The rpms in neutral you are describing is a rev limiter. This is the PCM keeping the rpms from going to high so you don't damage the engine. Most are around 4 grand in park/neutral.
I'm not positve what the limit in drive is for a Honda, I would have check on that but most will set a code when they hit the limiter in drive...
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Discretesignals
Ultimate Carjunky
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Nov 22, 2011, 7:20 PM
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Re: Help - 2004 Honda Accord RPM's Flat-Lining
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Not positive, but from the description of your symptom it appears the engine speed is being limited by the ECM when the transmission is in gear. Normally the rev limiter is active in park or neutral. This will probably require an enhanced scan tool to figure out what is actually going on. Some codes are manufacture specific and may not turn on the check engine light.
The whining noise could be related, but your going to have to try and pinpoint the source of the noise.
Sidom beat me...
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Nov 22, 2011, 7:21 PM)
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MACooke
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Nov 24, 2011, 10:55 AM
Post #6 of 8
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Re: Help - 2004 Honda Accord RPM's Flat-Lining
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NEW INFO:
Yesterday the high-pitched whining was traced to either the power steering pump or the alternator. Last night, while driving around town, the radio went dead, then the interior instrument and dash lights started dimming. Next my headlights started dimming, then all instruments went dead. As I passed under a streetlight in my neighborhood I could see the tach and speedometer's "jumping" from zero to about 10% reading. Gas and temperature gages were dead, on zero.
This morning I took my multimeter and checked the voltage across the battery terminals, engine off, 11.9 volts. I started it, it was slow to crank and fire up, then the voltage was 14.1.
Any ideas? I appreciate all your input. Thanks.
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Discretesignals
Ultimate Carjunky
/ Moderator
Nov 24, 2011, 11:20 AM
Post #7 of 8
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Re: Help - 2004 Honda Accord RPM's Flat-Lining
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From the symptoms you were experiencing it appears the charging system wasn't operating and the vehicle was running strictly off the battery.
You'll have to monitor the charging system voltage to see if it quits charging. Sometimes faulty alternator regulators will fail when the get hot.
If you do find the alternator is the culprit, you should be sure the battery is fully charged and load tests good before replacing an alternator. You don't want a new alternator getting fried trying to charge a dead or faulty battery.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Nov 24, 2011, 11:22 AM)
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MACooke
Novice
Nov 27, 2011, 6:27 AM
Post #8 of 8
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Re: Help - 2004 Honda Accord RPM's Flat-Lining
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Thank you all for your help. It was the alternator, got it replaced on Friday (11/25). I checked the battery before we started, it was showing 13.6V so we forged ahead. Took my father-in-law and I about an hour and a half to do the job, we replaced the serpentine belt too (that was most of the work).
Thanks again!
Mitch
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