Idle RPM

Hot Ducer · Jul 5, 2016

Where does your truck idle? Recently, ince it gets to temp my truck will idle as low as 500 RPM isn't rough and doesn't "search" for idle speed, but I dont remember it being that low before.

2003 1500 QuadCab 5.7 4x4

Harley Harrold · Jul 5, 2016

My 2007 Ram Quad Cab 5.7L Hemi idles at 800 rpm at normal operating temp. It will sometime drop down to 600 rpm when hot, and idling for a while, but always runs smooth at that idle.

Hemipower95 · Jul 5, 2016

This is what I meant

ExpressRules · Jul 8, 2016

Hemipower95 said:
This is what I meant

Good to hear you mean it. :shakehead:

Ajwalk2008 · Jul 8, 2016

I'm having the same problem. Mine feels like it has a miss but coil packs test good and has had a tune up in the past 3 months

Ceri · Jul 8, 2016

Idle can be affected by a dirty throttle body. Its minor, but has the greatest impact at low rpms and idle. 600 is typical for a fully warmed up hemi.

Hot Ducer · Jul 10, 2016

Ceri said:
Idle can be affected by a dirty throttle body. Its minor, but has the greatest impact at low rpms and idle. 600 is typical for a fully warmed up hemi.

Good call, pulled it apart today and my throttle was dirty as crap! Chock full off sticky residue. Cleaned it all up and it's sitting between 600-700 now. Thanks for the input. The gas pedal is more responsive now. Not greatly, but noticeably enough.

2003 1500 QuadCab 5.7 4x4

Ceri · Jul 10, 2016

Hot Ducer said:
Good call, pulled it apart today and my throttle was dirty as crap! Chock full off sticky residue. Cleaned it all up and it's sitting between 600-700 now. Thanks for the input. The gas pedal is more responsive now. Not greatly, but noticeably enough.

2003 1500 QuadCab 5.7 4x4

Sweet! Love that kind of job. Getting a little dirty and doing it yourself. Inmediately resolved.

Hot Ducer · Jul 10, 2016

Yep, just wish I had woken up early and done it before it got to be 95 degrees outside.

2003 1500 QuadCab 5.7 4x4

Ajwalk2008 · Jul 10, 2016

Ceri said:
Idle can be affected by a dirty throttle body. Its minor, but has the greatest impact at low rpms and idle. 600 is typical for a fully warmed up hemi.

I've done that already and it was no help. Could it be a bad injector?

Ceri · Jul 11, 2016

Ajwalk2008 said:
I've done that already and it was no help. Could it be a bad injector?

I couldn't rule it out, but I'd guess its due to air intake, emissions system, or vacuum issues. If there's no roughness to the low idle, then I'd lean away from a dirty injector. No codes? Brakes working 100%? If you had a vacuum issue, you might feel it in decreased braking performance. Air filter looking good?

Ajwalk2008 · Jul 11, 2016

Ceri said:
I couldn't rule it out, but I'd guess its due to air intake, emissions system, or vacuum issues. If there's no roughness to the low idle, then I'd lean away from a dirty injector. No codes? Brakes working 100%? If you had a vacuum issue, you might feel it in decreased braking performance. Air filter looking good?

K&n cold air intake cleaned every other oil change. Braking hasn't changed since I got it back at the beginning of the year. No codes no nothing. Cleaned the throttle body. Replaced plugs and wires about 2 months ago.

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Ceri · Jul 11, 2016

You might start a new thread and see if anyone else has an idea then. You could try replacing the PCV valve. Its easy and only about 20 bucks. I'd recommend it around 100k miles as regular maintenance anyway. Not saying that will fix it, but it couldn't hurt. I'd also mention the EGR valve, but its more like 40 and takes a little bit longer. You could still do both in about an hour. I assume you don't have a tuner installed because many of them can manually adjust the idle rpm.

Ajwalk2008 · Jul 11, 2016

No tuner as of yet. I'm at about 90k so I might try the pcv valve. Thanks for the help ceri

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Ceri · Jul 12, 2016

You may try resetting the adaptive memory too. With summer coming on full strength, it might need to relearn. Its a free shot in the dark.

Ajwalk2008 · Jul 13, 2016

I actually did that monday night since I put my cat back on over the weekend noticed a little difference in the idle. Constantly staying around 600-650 now where it was at 500-550 before

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Ceri · Jul 13, 2016

Ajwalk2008 said:
I actually did that monday night since I put my cat back on over the weekend noticed a little difference in the idle. Constantly staying around 600-650 now where it was at 500-550 before

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Sweet! Sound perfect, in more ways than one I trust.

Jeff Strader · May 8, 2023

A 5.7 Hemi's PROPER idle range is 600-625rpms, while in gear, and at a full stop. One person above, said 800rpm's is the proper range (TOTALLY INCORRECT). If your 5.7 Hemi is idling at at 800rpm's or higher, then your having either a fuel/air delivery system issue or your Cataletic Converters are clogged up, or in the process of clogging up, making it hard for the engine to properly dispel the exhaust gases, thus causing excessive engine back pressure, in which is forcing the engines ECM (computer), to try and compensate for the problem. ALL 5.7 Hemi's are pre-set by the factory to run at 600/625rpm's (while not under load) while engaged in gear, at a full stop...........5.7 Hemi's idling at 500rpm, will generally cause the Alternator to dispel the improper voltage output (too low). There's multiple important reasons why engines are set to idle at given rpm's. Proper Alternator voltage output is one of them.

Idle RPM

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