MDS issue, misfire at low RPM

[Johnjacob]

Total rebuild on 2007 5.7 hemi (spun 1st and 2nd main) everything back together including new MDS solenoids (old ones broke removing) and runs like a ***** ape unless your in town puttin around..... Misfires bad, pull over shut it off and restart and runs fine. Ive read possible ECM but how would I diagnose it to be that without buying one.... Any suggestions would be greatly appreciated.

 

[Bloody_Knuckles]

Spend a few more bucks and delete the MDS.

 

[Johnjacob]

Ive considered that.... I can get the plugs for $12 a piece. But id like the truck to run the way its supposed to

 

[Bloody_Knuckles]

MDS isn't worth squat in a 5200 lb truck.

 

[Johnjacob]

Besides plugging the holes where the solenoids were located what else need to be done?

 

[LoneWolf3574]

Besides plugging the holes where the solenoids were located what else needs to be done?

The PCM needs to be flashed to remove the MDS solenoids from the programming, otherwise, you will get codes related to MDS faults. The advantage is that IF you ever change out your cam, you don't have to worry about finding one that is compatible with MDS.

 

[Johnjacob]

Lifters do not need to be replaced?

 

[LoneWolf3574]

The MDS solenoids stop the oil flow to the lifters on four of the cylinders (1, 4, 6, and 7 iirc) causing them to collapse, so there is no need to replace lifters if all you're doing is disabling the MDS.

 

[Johnjacob]

Thats what i was figuring but other people aaid i needed to do the non mds lifters

 

[LoneWolf3574]

Thats what i was figuring but other people aaid i needed to do the non mds lifters

Yeah, that is only necessary if you are putting a non-MDS cam in. I should have stated that bit earlier, my apologies.

Sent from my LG-H830 using Tapatalk

 

[Bloody_Knuckles]

The MDS solenoids stop the oil flow to the lifters on four of the cylinders (1, 4, 6, and 7 iirc) causing them to collapse, so there is no need to replace lifters if all you're doing is disabling the MDS.

So are the solenoids normally open and powered to close for MDS?

 

[LoneWolf3574]

That is my understanding of their operation. They don't need to be replaced unless you are swapping out your cam for a non-MDS type, and it is usually a good idea to replace the lifters when you replace the cam in my opinion.

 

[Bloody_Knuckles]

That is my understanding of their operation. They don't need to be replaced unless you are swapping out your cam for a non-MDS type, and it is usually a good idea to replace the lifters when you replace the cam in my opinion.

Yes, I have rebuilt a few engines and the cam manufacturer ALWAYS recommends new lifters with a new cam. Plus they are pretty cheap.

 

[Johnjacob]

Ive been driving with the tow/haul on and have had no issues..... Does the tow haul disable the MDS? The only place around me that deletes MDS wont return my calls. Wth? Can i do it myself?

 

[justin13703]

Ive been driving with the tow/haul on and have had no issues..... Does the tow haul disable the MDS? The only place around me that deletes MDS wont return my calls. Wth? Can i do it myself?

Tow/haul does disable the mds and you can turn it off permanently with a tuner.

 

[Johnjacob]

Whats a good tuner?

 

[Lilkenny99]

I had the same problem with my 08 5.7, I got the diablo sport predator 2 for around $300 heard good things about it but after installing the preloaded tune and it caused problems with the transmission. Honestly it was a **** show diablo was no help and I ended up just driving around in tow haul mode. I would give Diablo a shot you can disable the mds with it and if you have any problems with the thing send it right back.