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-   -   Is 500 rpm too low for idle? (http://www.jeepforum.com/forum/f13/500-rpm-too-low-idle-1466292/)

kb9mfd 01-20-2013 08:56 AM

Is 500 rpm too low for idle?
 
I am wondering if this is normal or I have something I need to look into. While in park or neutral it idles just fine around 700~800 rpm, its smooth and quiet. When I put it in gear or when I stop while driving, the rpm drops to around 500 rpm and it shakes and causes the whole truck to vibrate. I assume that is because of the low idle. Its not pulsing, missing, or erratic, just a steady vibrate. I am wondering if that is normal, or its idling too low, and if it is too low what to look for. The pcm is not reporting anything so I assume the sensors are fine. I just got it a couple of months ago and its the first jeep I have owned so I am not sure if its normal. (its a 4.0 I6) Thanks! - Jeremy

jnowak 01-20-2013 10:07 AM

Mine does the same. Gonna subscribe to see the suggestions. I have done all the standard cleaning. All I can come up with is its a combination of a iac on its way out and motor mounts worn out.

papitt 01-20-2013 10:20 AM

I'm going to say your about too need a torque converter. When it's at 500 does it fell like it is pulling more or that you have to press on the brake more than you should. TQ time.

rcMikeS1990 01-20-2013 05:36 PM

2 Attachment(s)
I don't know about the 4.0s idle, but my 5.2 idles incredibly low

Attachment 547340



Attachment 547339

Two different days, same low idle

ZeeJay1997 01-20-2013 05:51 PM

I'm not certain the same thing happens on OBD1 units, but my tach lags about 150 rpms behind what the PCM reports to a scanner.

Bigdjs123 01-20-2013 07:19 PM

Mine does the same too

kb9mfd 01-24-2013 04:19 PM

After some other looking around, 600 seems to be the norm. I read somewhere about cleaning the IAC, so I tried that and it now just idles around 600 and does not drop after shifting into gear, but it still shakes/vibrates. I guess I will count that as being old engine mounts. Since its a 95 I'm sure they are a little hard, and since its cold out they are probably even stiffer. - Jeremy

Proph2010 01-24-2013 04:51 PM

Quote:

Originally Posted by rcMikeS1990
I don't know about the 4.0s idle, but my 5.2 idles incredibly low

Two different days, same low idle

Mines is identical to your, no vibrations or anything abnormal either.

kyle_outrage 01-24-2013 06:50 PM

mine idles at 500 aswell but mine only shakes if im low on oil. everyone I know or have talked to has said that their 5.2 idled around 500

papitt 01-24-2013 10:11 PM

... Mine is a 6Cyl not the 5.2 But how low on oil is yours when it viberates .. My VIC says to check the oil .. but it's not low I checked it tonight . maybe a quarter qt low.. . What kind of oil do you run to keep it from vibrating or going low.
.. . I was about to swap mine over to Motor craft synthetic blend because I have a bunch of it. DO YOU SEE ANY ISSUES WITH IT.

Candymancan 01-24-2013 10:33 PM

Our 4.0 and 5.9 idle at about 500 rpms both.

PolkaPower 01-25-2013 08:34 AM

1 Attachment(s)
Mine sits right here below this mark.

Myusername1674 01-25-2013 08:57 AM

Quote:

Originally Posted by rcMikeS1990 (Post 14822624)
I don't know about the 4.0s idle, but my 5.2 idles incredibly low

Two different days, same low idle

Thats exactly how my 318 idles, low as can be. My friends got a 90's chevy 350 and it idles that low to. I think it may just be an old engine thing to do. Lol

FAlfani81 01-25-2013 09:31 AM

Quote:

Originally Posted by kb9mfd (Post 14820024)
I am wondering if this is normal or I have something I need to look into. While in park or neutral it idles just fine around 700~800 rpm, its smooth and quiet. When I put it in gear or when I stop while driving, the rpm drops to around 500 rpm and it shakes and causes the whole truck to vibrate. I assume that is because of the low idle. Its not pulsing, missing, or erratic, just a steady vibrate. I am wondering if that is normal, or its idling too low, and if it is too low what to look for. The pcm is not reporting anything so I assume the sensors are fine. I just got it a couple of months ago and its the first jeep I have owned so I am not sure if its normal. (its a 4.0 I6) Thanks! - Jeremy

Mine does the same. Idle is at about 500ish but I don't get any vibrations.

7 to 800 sounds a little high to me.

Maybe your exhaust it rubbing on something.

PolkaPower 01-25-2013 09:37 AM

Quote:

Originally Posted by FAlfani81 (Post 14850633)
Mine does the same. Idle is at about 500ish but I don't get any vibrations.

7 to 800 sounds a little high to me.

Maybe your exhaust it rubbing on something.

700-800 is normal. Possible bad IAC sensor.


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