Well that's for your waste gate! But like others have said, not sure why that would affect you rolling or coasting down the road! Someone else will be able to answer.

 

I can't recall what that hookup goes to right now Ken but your motor needs a bath bad...Not bashing, it needs it..

 

WOW!! Interesting, I would have NEVER thought of unplugging that plug. So did you leave it unplugged or did you fix it to where you can plug it back in?

 

Havnt done anything yet.
Was going to plug it back in and try to make sure thats what was doing it.

 

What exactly does a waste gate do?
I wonder if it will hurt anything to drive it unplugged?

 

wastegate lets out access exhaust to avoid over spooling. However most users disconnect their wastegate because the turbos are unable to produce more than 25 or 26 lbs of boost and the truck can handle 30.
So no, it should not hurt anything to leave it unplugged. As a matter of fact mine is unplugged and has been for a year.

 

So whats the reasoning behind unplugging it?
I know why I unplugged mine, but it doesnt seem to be the reason anyone else unplugged theres?

 

As far as I know it's to allow the turbo to make more boost. But I'm not sure on the deeper aspects of it!

 

The waste gate is to keep from "over boosting" and to keep your turbo from overheating.
exhoust normally runs through the turbo and that is what makes it spin, but if your boost gets too high, or the turbo is getting too hot, the waste gate will open and let the exhoust bypass the turbo wheal and go straight to the down pipe.

the reason for unpugging it is to try and keep it from opening, so that you can build more boost.

The part I am confused about, is that the waste gate opens using air pressure provided by the turbo, so if you are not producing boost, then unplugging it will do almost nothing unless the spring is worn out, and if that is the case, then the pressure in exhoust will be more then enough to push the wastegate open way before the turbo builds enough pressure to open it. (someone please correct me if I am wrong)
I would plug that back in and see if your problem returns, just to make sure that is the problem.

 

I was going to question your logic hear. (on most smaller rwd solid rear axle vehicles, the axle is what the wheel bolts too), but then I realized I was the one who was confused, I forgot we have full floating rear axles. That counts as my stupid moment for the day.

 

did you plug it back in and see if the problem comes back?

 

Hmmm, still a problem though, what's going to keep the gear oil in the rear axle housing if the axles are removed.

If you want to check the rear end, jack up the truck, remove the drive shaft, pull the axles out about 2 ", and measure the amount of torque required to turn the pinion. Should be 18-25in/lbs (NOT much). That will tell you if you have a problem in the carrier assembly.

 

A piece of cardboard or plastic top off a coffee can can be made to "cap" the end of the axle.

I have had to implement this "fix" a few times on Class 8 over the road trucks to limp back to the shop for repairs. If you see a rear end getting hot you can pull the axles to keep it from having a catastrophic failure before you can pull it apart.

 

Here are my $.02
The exhaust gases flow through the up pipes, past the turbine wheel, through the EBPV and out the downpipe etc. The wastegate is a short cut that allows the exhaust flow to bypass the turbine wheel. So, the wastegate bleeds off excess boost indirectly by allowing some of the exhaust gases to bypass the turbo wheel. The gate itself is controlled by a Wastegate Actuator. The actuator has a rod that opens the wastegate when boost is applied to the actuator's diaphram. Boost is provided to the actuator via the Wastgate Control, which is the item you unplugged.

Looking at a schematic of the powertrain control system...there are a variety of electrical devices under the hood. These can basically be sorted out into two groups. Sensors and switches/regulators. A sensor is a device that measures something and provides that information to the PCM. A switch and/or regulator is a device that performs work and is controlled by the PCM (or IDM). The thing you unplugged is a switch, so by unplugging it you have blocked the PCM's ability to open the wastegate and now your truck is running better.

So, one of three things must be happening. The switch is bad and it was allowing boost to open the wastegate, the PCM was asking the switch to open or the control wire is grounded out. I will rule out the first option because the problem would remain even while unplugged. So, your PCM must be commanding the switch to operate OR the control wire might be grounded somewhere. You can test this by getting a multi-meter and checking the two pins in the connector. With the key on, find the wire that has 12v...that will be your power wire. Check the other pin for continuity to ground. Check it first with the key off and then with it on. If that wire is grounded with the key off, then you are looking for a short in the wiring harness somewhere. If the wire is open with key off and grounded with the key on, then your PCM is controlling that switch and the next question is "why?".

 

I plugged it back in and tryed it again.
I was just like the brakes are on.
So I unplugged it again.