No. 4 is the second one from the front on the passenger side. They are located under the intake manifold. MDS Solenoid failure is relatively uncommon, so I'd just change the one that is bad. Also, be aware that this may not be the problem though. With an advanced quality diagnostic scanner you can physically check the operation of all the MDS solenoids individually. If they're working properly, you could have other issues. IMO, thorough troubleshooting BEFORE randomly changing parts is the best way to go about this.

 

I know throwing parts at something is not the best practice, i have already checked the PCM and also the oil pressure both show good. I figured for 60 bucks worth a shot. What else could it be if it isnt a solenoid? Car runs smooth has 75k miles new plugs at 68k was also changed at 33k, no shakes no shudders etc. I only have a BT OBDII scanner - what scanner do you recommend?

Should also note i was planning on checking the resistance of the solenoids and also the leading wires for correct ohms and short. Thanks!

 

I know throwing parts at something is not the best practice, i have already checked the PCM and also the oil pressure both show good. I figured for 60 bucks worth a shot. What else could it be if it isnt a solenoid? Car runs smooth has 75k miles new plugs at 68k was also changed at 33k, no shakes no shudders etc. I only have a BT OBDII scanner - what scanner do you recommend?

Should also note i was planning on checking the resistance of the solenoids and also the leading wires for correct ohms and short. Thanks!

How did you check the PCM? While it's possible that it is the solenoid, it is relatively uncommon for them to fail. $60 is not too bad, if you want to give that a go. Usually, when they've been in the engine for quite some time, they're a little difficult to get out and you may even break it when removing it.

The main components of the MDS system are the PCM (controls it) along with some engine management sensors that must be within a programmed range for activation, the wiring harness to the solenoids, the solenoids and the valve lifters. You said it runs fine but, is it going into the MDS mode? Normally, if there is a fault with the system, it will no longer function until it is repaired and the code is cleared. With some of the earlier 5.7 Hemi's, there have been a very few (that I am aware of) MDS valve lifters failures. Every one has had a problem with the latching pin that activates/deactivates the lifter. I am not sure what caused them, but I suspect a lack of proper maintenance may have had something to do with it. I guess it could have been part failure to though. I don't know of any later model ones that have had this problem. Sounds like you're on top of the maintenance side of it though.

Any "higher end" scanner/diagnostic tool that has most dealer/maintenance shop level capabilities, including functional checks of components, and checking all of the vehicle's electronic modules, will work fine. Your newer C should have more than 20 different modules. For about the past 6-7 years I've been using mostly Autel products. I started with the DS708, then upgraded to a MS 906 and now use an MS906BT, I also use a couple other scanners, mostly for easier reading of emissions readiness monitor status, and another (Appcar Diag FCA) for programming some vehicle functions and accessories. I also use an HP Tuner for engine/transmission tuning and for some of these functions too. IMO, a quality scanner is a must on today's computerized vehicles, These will work on ANY vehicle from 1996 going forward (and some older ones too)......basically any vehicle that uses the On-Board Diagnostic II (OBDII) system. That means almost anything you'll own in the future......unless you go electric.

I would recommend you start with the easy, inexpensive stuff first, like checking the wiring to the solenoids and plugs at the PCM, looking for opens and shorts, stuff like that. There are no other components between the PCM and the solenoids......wire(s) goes direct from the PCM to the solenoids. Make sure there is no corrosion or poor connections. If you get a better scanner, use it to check all of the modules, especially the PCM. Make sure your oil level is where it should be. Check your grounds. If you pull the intake so you can get to the solenoids, before removing it and you have the scanner, you can either check it that way or, unplug it and, using 12 volt test leads (one with battery power and one to ground, try to activate the solenoid. You'l hear it if it is working. If it's not, you know what to do.

Good luck and please keep us posted on your findings.

 

Glad it's hopefully fixed and there really wasn't a big problem of some sort. Yes, a bad battery can cause all kinds of weird things to show up that really aren't there. Let's hope the battery was the culprit. If not, post up again. That's another reason a good scanner is worth its weight in gold. By the way, it can also reset your "Change Oil" indicator.

I am like you, don't drive any of my 3 Hemi's very much, especially this past year, LOL. On driver now and 3 vehicles is not really too smart economically, but I just can't bring myself to get rid of any of them. If I do it'll be the one with the highest mileage and it's still in great shape.Combined, I don't think we put 12,000 miles on them in a normal year. My 05 hopped up 5.7 Magnum gets driven the least. I ordered it the day they came out and took delivery in August of 04, and I've been modding it, a little at a time, ever since and am finally just about done. It only has 92K on it. My hopped up 5,7 Jeep (jmodded exactly like the Magnum, see signature) has 117K on it and my 300C SRT8 has a mere 173K on it. It's stock except for a mild performance cam, bigger throttle body and my custom HPTuner tune on the engine and transmission.