So, this is a bit of a storey but I'm hoping for some insight.

Blew my motor up a few months ago ,07 ram 5.7 Hemi,
Got a shop to do an engine swap , that cost triplle than the agreed price but that's beside the point.
Anyways since j got it back I've had nothing but problems,. Terrible fuel milage and multiple cylinder misfiring, also disappearing coolant.
truck was running like ****..
Discovered there was a v
connector above the throttle body that had no clip and came loose, so ended up zip tying it back tight. also Vacuum line off the break booster that had nothing on it, after doing some research learned there was supposed to be a cap on it.
So there was a massive vacuum leak, so problem solved.
Next the coolant reservoir emptied 2 times with no leakage on the ground,ended up putting 8 litres into it throughout a couple of days, after that problem solved, lol

Still running like **** I changed an 02 sensor that my reader said was fault.
Still coming up with multiple misfire code,
So j changed all plugs. Ran fine on the highway, idling running like ****.
Ran my reader, says​ cylinder 2 4 6 and 8, all on the second plug for each cylinder,. So I finally decide to take it back to the scam shop who swapped motor because I couldn't figure it out.
On the way there oil pressure drops to nothing. Vehicle shuts off, won't start but turns over.
Got it towed to the shop and told me maybe fuel pump or relay in the fuse box. Then he tells me it all rooted from a weak battery.
Every problem is due to a weak battery

Can most of this stuff that's happened be cause by a weak battery, the random misfiring,the shutting down on highway. But yet I could still turn it over,. Or is this guy just trying to scam me even more.
I've never heard of a weak battery being root cause to misfire issues, especially since this was the same battery I had prior to seizing the motor,without issue.

 

These trucks are rather sensitive to low voltage conditions.... so, while it is *possible*, I suspect you have more than one problem going on there. Also, seems like the shop didn't do a very good job with the installation.....

What plugs are in there? Dodges don't really seem to care for the rare-earth plugs.....

Did the oil pressure drop off first, and then the engine died? Or did pressure drop afterwards?

 

Plugs that were removed were NGK, plugs I put in were champion platinum.
and it appeared that the oil pressure dropped and then the engine turned off.
Notice my cruise control shut down vehicle started slowing down and check gages light came on and only gage that was off was oil pressure.
The shop told me that he scanned it and codes coming up are low voltage and wrong key,. Also he mentioned a relay in my fuse box or my fuel pump.
Would a weak battery cause fuel pump to quit?
Doesn't really make sense to me as its a brand new alternator plus after the vehicle died it was still turning over, and didn't appear to be weak

 

Platinum plugs may be some of your issues.... but, the truck should still start.

Need to find out what you are missing at the moment, spark, or fuel.... Does the pump prime when you turn the key on??

 

Definitely need to stick with copper spark plugs in these trucks.

 

Intereating.. I didn't look up what kind of plugs it should take but I buy off of rockauto usually, and the copper were a bit cheaper, platinum said last 2x longer so I assumed that was the better option.
But the misfire issue was there to begin with, which was why I ended up getting new plugs.
The truck is at the shop currently but when I broke down I did try and start it and it fired a couple of times but didn't start.
Another issue when I went to pick the truck up is I was told I had to turn the key to the start position and then touch a wire coming from starter to the positive battery post, so I installed a push button so I could start it by myself.

 

What the heck? They couldn't fix a starting circuit issue????? Think I would be looking for another shop......

 

Yeah I had no idea there was even an issue with the starting circuit until I went to pick the truck up 😂