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Discussion Starter #1
So, on my 2010 5.7 with 73700 something is going on, there is hesitation with acceleration in normal everyday driving, from 40mph and up, the engine performance just does not feel right, with NO check engine light on. The only engine mods I have done are bullet catch can and K&N intake filter, this past Sunday I took off the throttle body and it was not bad at all, but I still cleaned it out, and the small sensor that is connected to the cold intake tube MAF sensor was cleaned but still no change to my problem. I’m thinking of changing the MAP sensor, and I was told that the EGR valve can be bad but I can’t find it, next to my alternator there is not EGR, it looks like there is a cover covering a hole in the engine block. Is it possible that my 2010 5.7 did not come with an EGR, or it was removed? and any other ideas of what to do?

My jeep was serviced by jeep dealerships with the previous owner for everything even oil changes and brakes
 

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Discussion Starter #3
well I have not got it done professionally, I don't think I need to, but I do use about every 2 months a bottle of seafoum, or chevron fuel injector cleaner, or some lucas injector cleaner, last night getting back from work I disconnected the MAF sensor my check engine light came on, and the MDS stoped working but the engine performed a lot better, no more hesitation with acceleration and less shaking under acceleration.
 

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Discussion Starter #4
on the Ram forums it seems like it's a MDS problem, it looks like some people just dicconect the MDS
 

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on the Ram forums it seems like it's a MDS problem, it looks like some people just dicconect the MDS
When this hesitation happens (or just before), is ECO or Fuel Saver showing on your dash display? This maybe as simple as a sticking MDS solenoid. Another way you could isolate weather it's the MDS is to autostick into "5" instead of being in "D". 5 disables the MDS. You could try the 5 with and without the MAF sensor connected, might show that it's the MAF sensor.
 

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Make sure the proper spark plugs were installed. Some dealers don't buy spark plugs directly from Chrysler and for some reason the same spark plugs purchased aftermarket have too high of resistance compared to the OEM purchased plugs and this can cause strange misfires and hesitation.
The 5.7 is extremely sensitive to spark plug resistance and many have had issues after changing spark plugs. There is a service bulletin about this I believe.
 

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Discussion Starter #7 (Edited)
So, it looks like I know what caused the problem of hesitation when accelerating, HEMI engines are sensitive to oil viscosity affecting MDS solenoid

When I got my jeep right after leaving the car lot, I checked the oil level and I needed to add some so I went and got a bottle of Lucas oil stabilizer, I have used Lucas on my XJ for years and think its good stuff.

When I added it to my HEMI and drove back 2 hours home I had no problem at all with accelerating, but I was new to the jeep commander and new to HEMI engines, at my first oil change I did 6 quarts of oil and 1 quart of Lucas, and still no hesitation when accelerating, two weeks ago I did my second oil change with 5.5 quarts of Royal Purple and Lucas oil stabilizer I did 1.5 quarts from reading the instructions it look like it needs about 2 quarts but I did only 1.5, it looks like that the HEMI was not happy about, but it seems now that outside temp are getting hotter and the engine is running hotter it looks like the oil is getting a little thinner, then in cold weather, and this past Sunday it was over 70 degrees in NJ and the jeep was accelerating nice and smooth, and I did the thing of driving on the 5th gear and it was accelerating nice and smooth, and now in normal D mode its good.

I think what ill do is in the winter I will not put Lucas oil stabilizer and only in the summer ill put only 1 quart of it.

Bottom line HEMI’s are sensitive to oil viscosity
 

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Arielxkjeep,

Are you still happy with the performance and certain that oil viscosity was the reason?
I have a 2009 5.7L and over the last while, at highway speeds if I stepped into the gas, the Jeep would shudder something fierce.
I swore it felt like the torque converter was slipping while in lockup.

After changing my spark plugs the problem went completely away.
It must have been misfire or similar although it didn't show up as a check engine code.
Acceleration was a lot smoother too. Hesitation was reduced.
The gap on the old plugs (which may have never been replaced by the PO) was huge...

Just wondering if you have any follow-up information.

Rick
 
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