Rpm moves up and down automatically during idle and slow speeds?

[professornizami]

when im at a stop light or parked, my 98 Honda Accord Rpm will automatically move up a little, like if im stepping on the gas pedal, which im not
so it’s kinda weird, and when the rpm goes up, it makes my car move forward, so i have to step on the brake harder to keep it from moving. It’s so weird

Topic

[professornizami]

lol I meant to say no ECL(Engine Check Light)

[jbone]

Yes clean throttle body and IAC.

[EricTheCarGuy]

I’ve never had any luck cleaning IAC’s. Since it happened after you cleaned the throttle body you might want to go back and check your work as something could have been left loose or you may have damaged or moved a connector. Lastly I’m with those that recommend resetting the computer as it might help. Disconnect the negative battery cable and touch it to the positive for a few seconds to reset the system. Good luck.

[BigC]

Hi professornizami,

Sometimes the vehicle has to be driven so that the computer can re-learn based on the sensor inputs/outputs. I know from past experience that after cleaning a dirty throttle body, the engine will idle at a higher RPM initially. Make sure all the electrical connectors are secure, and see if the engine idle smooths out after some driving. Good luck and keep us posted.

[pcmdjason]

Eric has a video on fixing Honda idle issues, especially the up and down idle issue.

[professornizami]

Thanks to Big C & Jason. I’ll try to drive around to see if that clears up and today I just checked all lines that goes from throttle body (Intake) to engine and all the electrical wirings and everything seems to look okay. But I’ll look into those videos now as Jason suggested. I’ll get back to you guys pretty soon.

[professornizami]

Thanks Jbone & Erick. Yesterday, I tried carb cleaner trick go find any vaccum leak but unfortunately tht didnt helped me out. But I’m having ECU(Engine Check Light) p0505 I even looked it up online so it says Idle Air Control Valve IAC. I’m planning on to clean tht out with a carb cleaner and replace it with a new gasket. I’m wondering would that be a good Idea? Any suggestions will be appreciated

[djdevon3]

Don’t just take it out and clean it for the heck of it. Diagnose and make sure it’s causing a problem. It’s an Idle Air Control valve right? Keyword being idle. You can test readings with the car sitting there. You don’t have to go driving around which is a much harder thing to do for a DIY’er. Test the readings. Make sure it’s the IAC’s fault. In a lot of Mazda and Ford’s the fluctuating idle will actually come from a bad O2 sensor or MAF not the IAC. Sometimes there is an air adjustment screw and if you’ve taken it to a mechanic recently they love to fiddle with that thing and it just makes the problem worse. Plenty of things it could be so why take things apart before doing more diagnostic work. Parts could always do with a good cleaning so your IAC will probably thank you for the love either way.

[professornizami]

Thanks Dj Devon 3. First off, I would like to thanks everyone out here who helped me a lot to fix my problem. Here comes the good news!!!! My car runs smooth now because I just cleaned my IAC Valve with throttle body intake cleaner and took me about to 1/2 hour to clean it because I was kept spraying and cleaning out with a cloth and put it back everything together and runs fine! I drove for about 20 to 20 minutes and stop at many lights including stop sings and waited to see if the rpm moves up and down but I didn’t do anything weird. So I’m so happy the car runs normal and I would like to thank you guys one more time for helping me out. (:

[dreamer2355]

Thanks for keeping us updated with the fix!

[c4prlm4st3r]

Quoted From EricTheCarGuy:

I’ve never had any luck cleaning IAC’s. Since it happened after you cleaned the throttle body you might want to go back and check your work as something could have been left loose or you may have damaged or moved a connector. Lastly I’m with those that recommend resetting the computer as it might help. Disconnect the negative battery cable and touch it to the positive for a few seconds to reset the system. Good luck.

Hi Eric,
doest it can be done in all car? Is there any problem? Since we short the negative to positive?

[EricTheCarGuy]

As I believe I said eariler I haven’t had any luck ‘cleaning’ IAC’s, I have much better luck replacing them, if it were me I would replace it and receck for the condition as the IAC’s of that time were known to have problems.

[baylen]

I like erics method of checking it..which is, when its reving up and down, tap the housing with a screwdrivers’ handle. But also if you know the solution then get it done right… 😉

[jbone]

I agree with trying to clean IAC and see if it is the problem, But it wont last too long so if u got the money get a oem new IAC and call it a day,Also use new gasket..You could also clean the MAF sensor with MAF cleaner, check your air filter too while your at it…

[c4prlm4st3r]

Quoted From c4prlm4st3r:

Hi Eric,
doest it can be done in all car? Is there any problem? Since we short the negative to positive?

thats what i want to know…will it harm the car to touch the – to +…..ive heard of the when intalling a voltage regulator…

[Author]

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