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I am now approaching 3000 miles so I have spent enough time to notice some little things and recently I found one condition that I notice some surging. It happens aroun 40-45 mph under light throttle and it happens more on a slight uphill. It is almost like the MSD is coming in and out maybe??

I even put it in cruise control to make sure it wasnt me off and on the throttle and that didnt matter. The tach bumps slightly when it happens too. Like maybe 100 rpms or so.

Anyone else?

Mine is an 09 Laramie with the 5.7l 5 speed auto 4wd.
 

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My 08 does that same thing at any speed if the cruise is on. It is the MDS kicking on and off.
 

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Yes, I've noticed the same type of surge. I've tried to duplicate this several times and it always appears just like you describe; around 45 mph while climbing a very slight incline i see a 200 rpm surge. It almost feels like the transmission is shifting back and forth between 4th and 5th. Once I top the incline, the rpm drops; like the trans has settled into 5th and everything seems normal again. I plan to take mine in to the dealer on Tuesday for this problem.
 

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I notice my tach needle bobbing when I have cruise set on the highway. If that means that it is going in and out of MDS mode then there is a problem because it's constant. Would make sense too considering the truck's mileage is pretty awful. If I stay right at the speed limit( 62 mph) I get maybe 18 mpg. Bump it to 70 mph and we are instantly at 13 or 14. My truck has just over 1000 miles on it, but irregardless if it needs that much fuel for 4 cylinders unloaded something is wrong. The truck is broke in for all intensive purposes. Rearend is broke in, the rings are pretty well set. Granted as things get used they free up but still. I have even done all the fluid changes in the powertrain( everything except the transmission). I will run it to 3000 or so miles and if this doesn't improve it's going back. Getting the same mileage while driving slower than what I do in my 6.0 litre powered 373(but only 29" tall tires and .83 overdrive so it revs a fair bit higher) geared 1500HD GMC that weighs around 8000 lbs is not acceptable. My tailpipes are getting pretty black so I doubt this thing is running at stoich either. And like I said I don't think my MDS is actually activating either.
 

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Well, I dropped off my truck with a decent description of the problem and they said they couldn't duplicate the problem. They did however re-flash my PCM per RRT #09-004, which is for spark knock improvements and noise, vibration and harshness improvements; I had complained that the idle wasn't as smooth as I felt it should be. The service writer wants me to drive it for a couple of weeks to see if the re-flash has any effect on the hunting 4,5 shifts. I'll let you know if I see any improvement.
 

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Thats odd. I usually drive with cruise set at 70mph, and I consistently get around 17.
Well this last tank has me at right around 15 mpg and that is 90% highway at 62 mph ( Canada limit is 100 km/hr) and accelerating like grandpa. For reference sake my loaded 2006 GMC's 6.0 litre is getting consistently 13 mpg @ 75 mph weighing around 8000 lbs with a roof rack. That truck runs on all 8 all the time, revs higher and has a pile more weight and wind resistance. What's this Dodge's excuse? I will run it to the 3000 mile mark and see if that changes anything. If not I will run it to some dealer somewhere and see what they have to say about it. Like I said, break in isn't some magical long drawn out process. Yes as resistance decreases mileage increases but that only takes so much time. By the condition of my tailpipes it's running way too rich and I am very doubtful the MDS ever activates at all. Hence the mileage and the tach bobbing around. I hope it improves because if not, I am not one really to complain on forums or screw around and I will just get rid of the truck. I would prefer not too but I didn't buy a new truck to get 15 mpg, or less. I may as well get most of my money back and use it for fuel in some $3000 mid 90's TBI Chevy........but I am pretty usual at getting around 20 mpg in those.
 

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Interesting stuff guys. Has me somewhat concerned about the 09 I ordered and expect in 4 weeks. Strange though. I've got an 01 Dakota that has 106,000 miles but started 3 - 4 months ago having the same "surge" problem described here on new Rams. Guy I work with mentioned something about a sensor needing replacement. Something about gearing not "locking" (I'm assuming it could not select the right gear as someone stated above). Have not had dealer look at yet but wanted to post here as an FYI. Will put on Dakota v8 Quad page as well. Thanks for info.
 

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Guys I'm telling you it is the MDS, I know that my truck is 3rd Gen but when I put my truck in 4th at 65mph my RPMs are 2000. Should be close to the same for your trucks (if you have 20s and 3.92s like me). When it drops into 5th without MDS on it is about1750 RPM. Then when MDS kicks in my RPMs jump to about 1850 RPM (I assume it does this to give the 4 cyl mode a bit more power, so it can stay in MDS longer). By the way it sounds your trucks are doing the same thing, you all should have an ECO light in the display to confirm this.

As for the milage STR8, I have had many HEMI owners tell me that these engines don't break in fully until 10,000 miles or so.
 

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Guys I'm telling you it is the MDS, I know that my truck is 3rd Gen but when I put my truck in 4th at 65mph my RPMs are 2000. Should be close to the same for your trucks (if you have 20s and 3.92s like me). When it drops into 5th without MDS on it is about1750 RPM. Then when MDS kicks in my RPMs jump to about 1850 RPM (I assume it does this to give the 4 cyl mode a bit more power, so it can stay in MDS longer). By the way it sounds your trucks are doing the same thing, you all should have an ECO light in the display to confirm this.

As for the milage STR8, I have had many HEMI owners tell me that these engines don't break in fully until 10,000 miles or so.
Well mine just dances around rpm wise. Maybe Dodge's tachs just suck the big one. I have yet to find any indicator of sorts on this truck to tell whether or not the MDS is on or off. Manual says nothing and neither does the EVIC or the rest of the dash cluster. My mother's 2006 is the same deal, no visual indicator. Rpms shouldn't really change either. To maintain speed with the torque convertor locked a 100 rpm increase will increase the vehicle speed. If the convertor is unlocked it would be lost to slippage, but locked up it cannot.

And yeah I am a Hemi owner. My car doesn't even have 10000 miles on it, just over 7000 actually. It's broken in. It was broken in before it hit 3000 miles for sure. Oil consumption is a very tell tale indicator. When it stops, your seal is as good as it gets. If your rings take 10000 miles to seal..........the cylinders are out of round and it's never going too anyways. That or you have extremely hard rings and that's not a good thing really either. That's as far as break in goes, rings and walls. There are minors such as the pushrods wearing into the rockers, the valves tips wear a bit, the valves themselves wear into the seats and on and on. Its the natural progression of an engine wearing out. For reference sake my car rips off low 13 second quarter miles ( custom tune, headers, intake, tstat and catch can) that correct to high 12's at sea level at over 112 mph. And it knocks down 21-22 US mpg easily. Truck will probably never hit that, but it's a nice thought because that 2006 of my mothers does 19-20 US mpg quite easily and has since almost day one. Our trucks are equal, hers is a loaded quad cab 4X4 with 392's and 20's. Mine is a crew, whoopee.

Injectors, O2 sensors and programming don't break in, they either work or not and are right or wrong. Quickly blackening tailpipes is a sign of open loop to me. Something is wrong with this 09, period. I will be talking to dealers when I get home from work........which is probably a waste of my time. I need tuning software for this truck.

That and really, even 17 mpg. A truck that is fuel injected, runs on only half the cylinders at cruising speed, which is a relatively low rpm( really low in that 17 mpg case because you have 321's) and that's all it can get. Carbed trucks from 40 years ago could do better than that with no overdrive transmission. I mean really, when a vacuum referenced fuel leak called a carb can do that or better running at higher engine rpm in trucks that have the aerodynamic consideration of a brick wall, that's a problem. There is something seriously wrong here. Sure the engine is 390 hp, I know that. But it's not 390 hp at 1750 rpm running on 4 cylinders. It's only a 345 cid V8, not some monster that needs that much fuel to just stay running. I don't expect 30 mpg or something retarded and never did. I even laughed at the 22 mpg rating on the window, but you would think 20 mpg would be attainable at least. I fully believe it is, and only time will tell.
 

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This is a quote from the Dodge engineers when they participated in a forum chat: "1st, when you are in MDS, the torque converter slips at 60-100 rpms to reduce the engine pulsation. This increases engines speed by around 100 rpms."
 

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I havent noticed any rpm surge. In fact, Ive noticed the opposite. When I lock cruise control at 69 mph, my rpms appear to drop slightly from 1800 to about 1600.

What is the maximum speed you can go and still have the MDS active? Ive heard it was 70, so if Im concerned about fuel economy, Ill lock in cruise at 69 mph.
 

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This is a quote from the Dodge engineers when they participated in a forum chat: "1st, when you are in MDS, the torque converter slips at 60-100 rpms to reduce the engine pulsation. This increases engines speed by around 100 rpms."
Well that's good to know. My convertor is constantly slipping the lockup clutch then, awesome. So how would you regulate that, just slightly release the lockup clutch in the torque convertor. I am sure the clutch loves that, slipping all the time. When it's unlocked the clutch really does nothing and it dampens locking of the body of the convertor to the turbine which gives you a mechanical connection to the front pump. Especially mine since the tach does the jump at a rate of about 10 pulses up and down per minute @ 62 mph.


I havent noticed any rpm surge. In fact, Ive noticed the opposite. When I lock cruise control at 69 mph, my rpms appear to drop slightly from 1800 to about 1600.

What is the maximum speed you can go and still have the MDS active? Ive heard it was 70, so if Im concerned about fuel economy, Ill lock in cruise at 69 mph.
Well that's normal because your torque convertor clutch locks up and you lose that slippage, thus lowering engine rpm. Unless the trucks are different than the cars the MDS is based more on engine load than overall vehicle speed. I too have heard it's about 70 mph just because above that the load on the engine becomes to high to allow it to run on 4 cylinders only. For reference sake the cars can see in excess of 80 mph and still run on 4 cylinders. The 08 and up LX chassis cars have a menu portion in the extended EVIC which switches from power to economy on the 8 to 4 shift. I wonder if these trucks have an "extended EVIC" so to speak. On the cars you enter a diagnostic mode and get more functions by holding the two center buttons on the steering wheel down. I have tried multiple ways on my truck and have gotten nothing thus far. Like I said earlier I don't have any "economy" light or what have you and therefore have no visual to see the transistion. Aftermarket exhaust would work I guess since if it's louder you will hear it when it runs on 4 cylinders.
 

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It has the EVIC light. Dodge has even mentioned it on the website about it having it. Just keep looking you will find it. There was a thread about this on here awhile back, I'll see if I can find it for you.

Here is a thread that mentions some stuff about the ECO. It also has a link to the Dodge webpage as well as to the JEEP webpage.
http://www.dodgetalk.com/forums/showthread.php?t=226563&highlight=mds+light&page=2

By the way it looks it should have an ECO Light that apprears in the EVIC.
 
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