4.7 erratic Rpm

[macsx6]

Anyone know a cure for my 2003 1500, 4.7 rpm's erratic at a stop or in park? I've changed the TPS, cleaned the throttle body and it was good for a week or 2. It seems to do it more on cold or rainy days but has also done it on warm sunny days as well. It's intermittent at best. Some days it's good and others it's constant. https://vimeo.com/146050989


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[macsx6]

And it's not throwing a check engine code.


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[Hemipower392]

my 4.7 did that, i thought it was just trying to show off

 

[macsx6]

Lmao. I wouldn't mind so much if that was the case but sometimes it's really bad and stalls out.


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[macsx6]

https://vimeo.com/146056852


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[Hemipower392]

oh man mine never stalled out

 

[xb1230]

When you cleaned the TB did you remove the IAC to clean it up and all the fine air passages it leverages?

If you clean the TB and not the IAC/passages, it's like taking a shower and putting back dirty underwear... Looks better but still smells!

 

[macsx6]

Originally, I cleaned the Tb when I did the TPS, about 2 months ago. Fixed it for about a week and definitely cured my jumping rpm's while on the highway/cruise. Tuesday, I pulled the iac and cleaned it with a rag and qtips, and cleaned where the iac installs with a rag. Drove 200 miles Wednesday and its still erratic, only when I'm at a stop or in park.


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[macsx6]

I'm wondering if I just need to replace the iac. What ever the cause, It's very rhythmic, happens every 2-3 seconds. Driving me crazy.


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[JAMMAN]

Mine does the same thing, getting ready to pull the throttle body and clean it.

Look for a vacuum leak too, on the way to the power brake booster behind the master cylinder. Pinch the hose closed while under the hood see if it stops warbulating LOL.

 

[macsx6]

I'll try anything at this point. Thanks for the heads up.


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[friggentruck]

+1 on checking for vacuum leak. On the same note, it wouldn't be a bad idea to throw a vacuum gauge on and see if it fluctuates with your engine rpm.

Replacing the IAC isn't a bad idea either. I did that recently as well and it significantly improved my idle (but still didn't fix my problem). Keep us posted!

 

[Cliffords Rig]

Mines been doing the same thing. On a cold start it'll normally miss the first turn over an when pulling in to parking spots slowly it will die.