High raising and falling idle speed, but normal when in gear

RPC

MEMBER
HONDA ACCORD

I have a unique probelm. My Accord EX V6 2000 model is at the body shop for front bumper work. It was there for about three weeks. When I go to pickup the car, I see all new issues which were not present earlier. I see a high idle speed that is raising and falling, I mean high and fluctuating idle speed (1500 plus rpm). When I move into gear the speed stabilizes and I have no probelm driving around. Can someone help me to get this resolved. The battery is new and it is good.

Please help.

RPC

7 Replies

BRUCE HUNT

MECHANIC
3,754 POSTS

The surging of the engine is not generally electrical. It can vary from sensor, vacuum leak, coolant level, air in coolant system, and intake manifold gasket or intake leak. You need to look the engine over real well to see if the hoses etc are properly connected. Check coolant, bleed the air out of it. Check dash for check engine light.

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Thursday, October 26th, 2006 AT 8:07 AM

RPC

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Check engine is now off after the battery is replaced. Yet this problem (surging and lowering idle speed) persists. And the vehicle had none of these problems, when it was taken to the body shop. My frank question is: if the mechanic played a nasty role in tweaking the system to create this problem, what he could have possibly done. I am sorry to be frank in my question. As I was positive this issue came up only in body shop, it was non-existent earlier. I suspect the mechanic might have tweaked little here and there that is creating the problems, like lossening the hose to cause vaccum leak etc. What can I suspect that could have happened at body shop that caused this issue. Your reply would definitely help me to discuss the solution with body shop. Pardon me if I am too rude in expressing my views. As said earlier, the check engine light is off with the new battery in place. Appreciate your expert views in this matter.

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Thursday, October 26th, 2006 AT 9:42 AM

BRUCE HUNT

MECHANIC
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Replacing the battery should only be a temporary turning off of the CEL. The codes should still be in the computer. The extent of the damage to the vehicle. An accident? Did the car get a new front end clip? Did they have to remove the radiator? Not sure what they had to do. They could have made an honest mistake and failed to hook up a hose, not bleed the cooling system. They may have accidently sat something on the engine that knocked off a hose or a wire. Look around very closely and even have a second pair of eyes help you.

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Thursday, October 26th, 2006 AT 10:42 AM

RPC

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Additional information I noted for the above issue is that the idle speed fluctuates in a rhythmic fashion between 1500 to 2000 rom only when the radiator colling fans (2 fans) switch off. As soon as the fans switch on the idle speed stabilizes (1500 rpm) at well above the normal idle speed. As informed earlier my car is Honda Accord EX 6 cylinder 70000 miles. I see no leakges around. The code reader gives code of P0505, which is related to Idle Idle Air Control Valve. Please suggest what needs to be done. The issue looks interesting particularly since the raise and fall of idle speed is only happenng when the radiator cooling fans get switched off. Thanks for your help.

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Saturday, October 28th, 2006 AT 3:17 PM

BRUCE HUNT

MECHANIC
3,754 POSTS

Here is what I would try. I would take the IAC valve off the car and carefully take it apart. Clean it completely. I believe there are screens in there and put the part back on. Bleed the system of air and see what happens. If the part looks bad replace it.