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Hi to all, have had a few dodge trucks and a Jeep and just picked up a 2008 ram 4X4 with the 5.7. anyhow just want to know if I have a major issue. truck shifts nicely through 5 gears but once I'm going 60 mph or so it seems to "hunt" between 4th and 5th gear. rpms range from 1500 or 1600 to a little over 2000. Wondering if the trans is going in and out of lock and how I could fix it.
 

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Red Trucker
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Is it popping codes? It sounds like it's initially having TC lockup issues. Those are usually fairly easily solved. If 4th and 5th (overdrives) clutches are starting to to then that's that. Rebuild or replace.
 

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Discussion Starter #3
No codes that I know of, I think its a TC lockup issue also once I think about it because 4th gear would be higher rpms than 2000 at 60 mph. If it's a lockup issue can you direct me for what to look for? I have read to check grounds, especially at the PCM
 

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Downloaded, Awesomedude, thanks very much. playing with the throttle this morning makes me want to believe its the tps.
 

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Discussion Starter #7
that's no good, I'm going to change out the pcv valve and when I do I'll probably clean the tb
 

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Hi to all, have had a few dodge trucks and a Jeep and just picked up a 2008 ram 4X4 with the 5.7. anyhow just want to know if I have a major issue. truck shifts nicely through 5 gears but once I'm going 60 mph or so it seems to "hunt" between 4th and 5th gear. rpms range from 1500 or 1600 to a little over 2000. Wondering if the trans is going in and out of lock and how I could fix it.
It might be the engine going in and out of MDS mode (running on 4 cylinders). I have an '06 Dodge Ram 1500 w/Hemi and I noticed that around those speeds it would show about 1600 rpm when in MDS and about 1800 rpm when it wasn't. Are you sure it is shifting? The MDS is pretty well seamless and the only way I knew it was in MDS mode was by watching the tachometer. Just a thought.
 

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Discussion Starter #9
I had no idea there was a MDS mode on these trucks, I do see some movement between 1600 and 1800 and then again I see it go from 17-1800 to a little over 2000, so I don't think it's dropping out a gear when it goes to 2000, just unlocking the torque convertor. Truck is actually running pretty good right now, I appear to be getting right at 13 mpg and still plan on cleaning the TB, replacing the PCV valve, changing the trans fluid, and flushing out the cooling system. My CEL came on during the weekend, and when I do a key dance it shows no codes, just dashed lines and then "done". I'll have to put a reader on it.
 

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Red Trucker
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I had no idea there was a MDS mode on these trucks
Yep, starting in 2006 in the 1500's. When they came out with the 6.4 in the HD's, it has MDS even though the 5.7 previously in the HD's did not. Definitely has to do with engine power and displacement. Never experienced it in a truck but direct comparison between a 5.7 in a car and a 6.4 in a car, my 6.4 will climb hills at 85mph still in MDS mode (at least until the hill gets too steep to maintain MDS and cruise speed). Amazes me sometimes.
 
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