Rpm fluctuates in park

[TheShowtime]

Hey guys i notice sometimes in park when in idle my rpm goes up and down slightly like I’m stepping on the gas lightly. Only when I’m in park I notice while I was getting gas today. I cleaned the throttle body and maf recently. Spark plug and wires are also fairly new. Anyone know what could be causing that? Thanks

 

[Brian.]

First guess is the Idle Air Control valve that lives on the bottom of the throttle body. If you're not careful with TB cleaning, you can flush a bunch of crud in there and cause issues.

Head on over to mtbtims youtube channel and look for his video(s) (I think there are 2) on this topic for more detailed info.

 

[Riceye]

Could also be the a/c compressor cutting in and out if you are in either defrost mode. Try changing settings.

There is a simple mod to disable if this is the cause.

 

[brillo_76]

How much of an rpm fluctuation are we talking about here?

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[TheShowtime]

Revs up to 1500 rpm then goes back down. It’s not always like that just sometimes.
I noticed the idle is rough when I don’t drive it for a couple days and start it up also. But only for a min or two then goes back to normal.

 

[Bumbo]

This post isn’t going to help anyone, but back in the day when I got my first car (Honda Accord) I installed a pretty aggressive stereo with a large electrical load…

On cold days when the engine was high idle, anytime the bass hit the RPMs dropped like 200-300 RPM.

Probably starving the electrical system with spiked voltage drops… either way, I was rather pleased with myself.

 

[brillo_76]

Revs up to 1500 rpm then goes back down. It’s not always like that just sometimes.

I noticed the idle is rough when I don’t drive it for a couple days and start it up also. But only for a min or two then goes back to normal.

So sometimes it rough idles at cold?? As mostly rough idle at cold can be a vaccuum leak. Maybe I missed it and my apologies but what year is this 3rd gen?

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[brillo_76]

This post isn’t going to help anyone, but back in the day when I got my first car (Honda Accord) I installed a pretty aggressive stereo with a large electrical load…



On cold days when the engine was high idle, anytime the bass hit the RPMs dropped like 200-300 RPM.



Probably starving the electrical system with spiked voltage drops… either way, I was rather pleased with myself.

Yes you took the current level below a threshold and starved your ignition, fuel pump and the entire electrical system for current.

My one buddy had a covertable ford ranger when we were in college. When his bass hit at idle it would kill the engine. but this is way off topic of the subject at hand.

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[TheShowtime]

So sometimes it rough idles at cold?? As mostly rough idle at cold can be a vaccuum leak. Maybe I missed it and my apologies but what year is this 3rd gen?

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It’s a 2001 3.4 V6

 

[brillo_76]

It’s a 2001 3.4 V6

Ah. Throttle by wire hybrids. [ 2001 2002]

Those throttle bodys are more complex. Quite possible it all needs clean and you have to be careful. Those are actually servo controlled and the throttle cable is a fail safe. Etc.

However, they are also more modern. As everything newer is throttle by wire.





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[plcfcng]

This post isn’t going to help anyone, but back in the day when I got my first car (Honda Accord) I installed a pretty aggressive stereo with a large electrical load…

On cold days when the engine was high idle, anytime the bass hit the RPMs dropped like 200-300 RPM.

Probably starving the electrical system with spiked voltage drops… either way, I was rather pleased with myself.

My RPM fluctuations were not that large only 25 to 50 rpm at idle in drive. I happen to have my Charging light come on so I replaced the brushes in my alternator. Now my RPM is steady as a rock. Must have been a voltage issue. not a 1500 RPM difference but something to what out for.:llama:

 

[Ryan and Jerri]

High fluctuations for voltage drops but ya maybe start there. Test your alternator and battery. And clean your battery terminals while you're at it. Couldn't hurt.