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Discussion Starter #1
Guys,

Got this persistent issue with the rpm going berserk randomly, even if it just started, or in the middle of the drive, or ending my drive in park...

The engine's rpm goes sky high and only you can do is turn it off. One time I nearly crashed to the car in front of me coz the engine went crazy, luckily got it to neutral, press the brakes like mad man and engage hand brake!

Any of you experienced this?
 

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First thing scan for codes. Question is when you turn it off and restart does the engine speed reset back to normal idle or stay high?
 

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Discussion Starter #3
After turning it off, it will go back to normal though. But I'll be ready for the next random attack of the surge. Tried to scan, nothing unusual found, not even check engine is lit.
 

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2005 I don't think is drive by wire? Check throttle cable for sticking. I have seen bad engine earths causing that problem. Do you know if it's drive by wire?
 

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The LC Accent engines aren't drive by wire so the problem is highly unlikely to be electrical.
The engine needs air in order to rev so you might have a vacuum leak. Perhaps the brake servo/booster hose is split. How does the brake pedal feel?
 

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Discussion Starter #6
Oh sh!+...i mean 2004! Sorry my bad...(Out of topic: can i edit post title?)

Drive by wire? I see throttle cable near the IAC that's bend in U..is that what u meant?
 

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Discussion Starter #7
The LC Accent engines aren't drive by wire so the problem is highly unlikely to be electrical.
The engine needs air in order to rev so you might have a vacuum leak. Perhaps the brake servo/booster hose is split. How does the brake pedal feel?
Brake's feel good. Nothing unusual to the ordinary
 

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You can check for air leaks by connecting a vacuum gauge and it should have around 20" at idle. What my comment about the bad earth is that the accerator cable becomes part of the engine earth and the high current causes the cable to start binding. By the sound of it it's more than a high idle speed.
 

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Discussion Starter #10
Just bumpin' this post.

This issue has been fixed. What I made/repair:

  • Cleaned out all sensors and injectors
  • Replaced the IAC (used the old one and it works!)
  • Aux fan operates upon ignition (I will deal with this later if I can find a new aux fan sensor)
  • Detached the auxiliary fan sensor (this is the culprit! It sends the wrong signal to the ecu, it send random rpm spikes then turn the engine off!)
No random rpm spikes, engine runs great without the abnormal engine off!

Thanks guys!
 

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Good to see it's fixed. The fan your talking about. Is that the air con fan? There is an idle up that occurs when the extra load is put on the engine so that's where there looks like a problem. I wouldn't think the extra load would be enough to cut the engine off but rather have a slow rough idle.
 
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