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Old 08-24-2013, 11:38 AM
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MDS problems - need help

Here is the bottom line question, could running with the ignition cables wrong cause internal damage or problems with MDS? And what should I do next?

2005 5.7 Hemi JC LE sent to shop for tune up. They installed new Champion 570 plugs and ignition cables (2005 is the only Wk with cables). Drive home was rough and sounded bad. The next morning it would not start, black smoke coming out exhaust. They towed it back and eventually (2 days later) found they installed the ignition cables wrong. Yes they admitted it. After they fixed the cables new problems and sounds have started. On the drive home the engine light came on (code 3497 - MDS error bank 2) and mileage was 10 mpg. After more digging, definitely the MDS is having problems engaging and disengaging. When running in 4th gear instead of Overdrive, no problems. I asked them to reset the MPS and they said that think they did with their Solus Pro, but MDS is still having same problems. More digging and today I found they left the CAI tube off, when I put that back on the mileage has improved to about 13-14mpg. Obviously I have some major issues with the auto shop but wondering your thoughts and what would you do? Since they know they screwed up they are trying to help but not sure if they are helping or hurting. I'm afraid if I cut ties from them and there is major engine damage they will just say it is the next person's fault. Its a mess. Also, I'm still not sure what to do about the MDS system.
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Old 08-24-2013, 04:35 PM
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Re: MDS problems - need help

Hooking up the wrong wires to the wrong cylinders is not at all good, and could potentially cause other problems. One way to remedy this is to get rid of the "rat's nest" going over the top of the engine. Too bad you didn't check here first, as many (including me) with 05 Hemi's would have recommended you go with the Taylor Shorty wires. This eliminates the "Wasted Spark System" that was only used on the 05's, and eliminates the potential for what happened to you.

What happens when the "over the top" wires are hooked up wrong (depending on which went to what cylinder), you could get premature firing or late firing, which could cause no start, bad cylinder missfire on the affected cylinder, or potential damage to the internals of the engine, depending on how much load (throttle opening) was put on it during that time. How long was it run this way? If just a very short time (a WAG, less than ~10-15 min. or so...light load), probably not an issue, but if driven many miles that way, possibly and issue. Do you know what they gapped the spark plugs to. Should be .043-.045 in. stock.

MDS issues can be caused by a number of things....first and foremost, putting the incorrect weight oil in the engine. It must be 5W-20 (IMO, preferably synthetic) for the MDS to work properly. Otherwise it will be erratic, slow to activate, or not work at all, depending on the weight oil installed. Also, if they messed with the PCM....reset, flashed, etc. the 05's will completely disable the MDS for ~10-25 miles, and then it will magically start working again. The 06's and later do not have this problem....change something and it works immediately. Apparently some computer reprogramming was done between the 05's and 06's. I know this because I have an 05 Hemi LX and an 06 Hemi WK, and anytime I do something to the 05, it irritates me that I have to drive it some distance before the MDS starts working again. You may want to hook up an MDS "ON" light so you know for sure. Well worth it. I came up with this back in 05 for the Hemi LX's and it also works (same wiring diagram) on the Hemi WK's. Here's the link under my LXforums screen name, "magnuman": Installation of a MDS ON Indicator Light If you want to do it and have questions, let me know.
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Old 08-24-2013, 06:31 PM
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Re: MDS problems - need help

Thank you for the response. I hoped you would see this as I have read many of your posts. As for installing a light, that would be easy to do but I'm not sure where to go after that. Currently, it is very obvious when MDS kicks in, you can feel the momentum change (sort of feels like downshifting as those 4 cylinders are disengaged). Then as soon as the throttle is increased there is a sudden surge and acceleration.

I'm going the Dealership in regards to the recall on the transfer case solenoids. I know that is a software fix, so I'm wondering if the download will reset the MDS or is there anything they can do with their computer. I currently have no error codes so they are not going to see anything.

As for the spark plugs they were supposed to be 0.045 and it clearly shows the oil weight should be 5W-20 but at this point I'm not sure I believe anything from them.

Do any of the OBD scanners (Solus Pro) show more diagnostics on the MDS system?
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Old 08-24-2013, 10:00 PM
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Re: MDS problems - need help

Code scanners normally won't give you actual MDS information, other than DTC's relating to it. There used to be an MDS "reset" for the 05's, but that was eliminated (I've tried it), probably mostly because it didn't do anything. If you have a tuner, be sure to return it to stock BEFORE you take it into the dealer for the recall. If you don't, you're tuner will become a paperweight and cost you ~$100 to get it reset. If they hook the StarScan up to it and reflash the PCM/TCM, your MDS will probably not work at first. Not to worry though, just drive it and it'll eventually start working again. This is on the 05's only. Not an issue on the 06's and above.

Are you sure it's the MDS you're feeling and not the torque converter clutch cutting in and out? Sometimes both the MDS and the converter clutch are "doing their thing" simultaneously, and it's hard to differentiate between the two. This is particularly true on the highway, where both actions are more noticeable.

If your fuel economy still sucks and you've installed new plugs and wires, you may have an O2 Sensor(s) (or other sensor[s]) going bad. Many of these will start failing, adversely affecting fuel economy, but still not throw a DTC. Another problem could be the EGR Valve. This will cause erratic, almost stalling idle, noticeable low speed surging and poor economy and performance. Anything over (I am guessing) ~65000 miles on the odometer, I'd start looking at these things.
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Old 08-25-2013, 03:06 PM
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Re: MDS problems - need help

Great info. Thanks again. There are 2 reason's I feel its the MDS. Code 3497, relates to the MDS system, came on one time. But also, when I drive it in 4th gear instead of 'Drive', that is supposed to disengage the MDS. I never have surges or problems when set to 4th gear.
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