My 2000 ram 5.2 manual trans runs awesome except when climbing a large hill. It backfires in the engine compartment it looses power. I down gear and it chatters. I've done plugs wires cap and rotor also new ignition coil. It has excellentfuel pressure and good spark at idle. When not moving I can tach 4000 rpm hold it there and it sounds perfect no backfire. Only when climbing a hill. I live on a mountain so... also it throws no codes

 

How's the plenum?

 

It's clean and the gasket is new

 

Hhhmmm..... Has the trans been out in recent memory? Almost sounds like a marginal crank sensor.

 

Does it actually backfire or does it miss?




Just want to confirm...

 

Transmission is original I only run the mopar nv3500 fluid and I change it regularly. It shifts fine it's definitely a backfire sound but coming from engine area and no power until I down gear

 

It's a loud backfire sound that u hear and feel from engine compartment

 

Still trying to get a feel for this weird problem...

Did you check the crank sensor yet?
Can we assume that, because it's loaded (and heavy), your RPM's are higher? Can you duplicate the problem simply by revving higher, before you shift?

 

You said it chatters when you down gear. Are you hearing pinging like its pre detonating?

 

I replaced the crank sensor at 180000 truck now has 251000. When it went bad it threw a code yes when I down gear power comes back but it chatters like I put lower grade gas in it.