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Discussion Starter · #1 ·
When I drive with four wheel high on or even Auto just to test it I noticed loud screeching when I let off the gas start to slow down it kind of thumps in the rear and when I put it in four wheel high and it's sitting at an idle it idles very high and rough what could cause this it's a 2006 LS model?¿
 

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I don't believe there's any need for additional idle speed compensation in 4WD or AWD while you're sitting at a light or generally stopped in gear. The engine load is going to be the same if you're not in motion ... so I'll step into the debate here by saying that.

Once you start moving, there will ... naturally .... be a loss of performance as far as acceleration and fuel economy, etc.

"Thumping in the rear" might just be the control arms or a frame member that's rusted out and hanging in midair. Take a serious look under there --- by going to a tire store and ask them if you need brakes "because you hear a funny noise in the rear brakes" and while they're salivating, your car will be in the air, wheels off for an "inspection" which is really an implied license for them to hold you and your car hostage.

BUT - they have no right to impound you or your car except in some nanny states where they will tell you it's illegal for them to let you or your car leave ... that's not technically true.

To tell you the truth, if they do find something totally kamikaze under the car - you'd WANT to know and then you can have it towed (which you should do anyway if it's that bad!) to your home --- or wherever you want.
 

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Discussion Starter · #3 ·
What I'm saying is it naturally idles high and rough for whatever reason I don't have to do anything to it except engage it. And I'm not real sure what the loud squealing is.
 

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Let me see if I got this straight. You can be idling in drive in 2wd and if you switch to 4HI or A4WD the idle increases?
 

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Wonder if maybe there is a failure in the front differential or splined disconnect and there are gears grinding/slipping.
 

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Do you know if the rear axle, rear differential, or front differential are all original? Have you had this truck long? Did it work ok before and then just start doing this?
 

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Discussion Starter · #14 ·
Do you know if the rear axle, rear differential, or front differential are all original? Have you had this truck long? Did it work ok before and then just start doing this?
Ha just bought it bc I loved the 06 I had before. Took him at face value that it worked and he didn't lie it does work.... Just has some issues attached.
 

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So I have seen several instances where someone changed a rear differential or rear axle or had an engine swapped in and the used then donors front differential. Which is fine if the gear ratios match. But if they do not match and you shift into 4WD they generally wil go about 4 feet or so and then bind up which would feel like you just dropped an anchor.
 

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Quickest simplest way I know to prove the differentials match is to put it in 4hi, jack up one side of the vehicle front and rear. The other side MUST stay on the ground. Put it in neutral. Mark the tires at the top. Turn one like 8 or ten times and the other tire must turn exactly the same.

Like this:

 

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When you're driving in 4Hi or A4WD, you're not on dry pavement, are you?
The OP stated: "when I put it in four wheel high and it's sitting at an idle it idles very high and rough what could cause this it's a 2006 LS model?¿" ..... so what you're saying doesn't matter.

The idle should not be doing what it's doing.
 
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