Ok im a new member but I have been viewing posts for a while now trying to get to the figure out the problems with my truck (96 1500 V6) . It all started back in December when I noticed a loss of power and a backfire on the right side starting to happen on acceleration. It only does it when the truck under load. It will not back fire while in park or neutral. I replaced the cap, rotor, plugs, and all the plug wires as well as the coil and its wire. No change. I also checked out the cat and it is not clogged. Next I checked my fuel pressure which was low. I replaced the whole fuel pump assembly and the vacuum lines from the evap canister to the fuel pump assembly. That gave me some of my power back but it started to shutter which was due to injector 5 was trying going out, which It finally did this past week. I replaced the injector and got almost all of my power back but now I am back to square one with the back firing issue. I have ran vacuum tests as well as compression tests. Vac is fine and the compression is a little low in a few cylinders (normal on an all original motor with 200,000 miles) but not enough to hurt anything. I have also checked out all of the censors around the throttle body as well as cleaned the EGR valve PCV valve and both are working fine. I am now at a loss as to what is going on. I have checked out everything that I know of shy of pulling the motor apart and inspecting the valves. Is there anything else it could be that does not involve having to pull the heads off?

Thanks

1996 Dodge V6 1500

 

I would be tempted to pull the plugs on that bank out & getting a look at the top of each piston. I wonder if predetination may have punched a few small holes in 1 or more. Otherwise, I would really look into a shorting wire. That can be elusive when the insulation looks fine but the wire inside is broken. For instance, the wires inside the insulation of an injector touch & it works, but then they dont sometimes & by the time it fires again with some fuel in that cylinder, it backfires.

 

by backfire - i'm assuming you mean backfiring into the plenum or up into the throttle body. correct ?

so you checked compression and its normal, meaning somewhere in the 100-140 psi range on all cylinders. this rules out a leaking intake valve not holding compression and allowing fire back into the plenum. (and holes in the piston).

you also ruled out a clogged cat. somehow..

you could still have a bad injector, leaking or misfiring at the wrong time.

you could have a bad cam position sensor, firing the injectors at the wrong time. its inside the distributor cap.

you could have a fuel sync issue, firing the injectors at the wrong time. you haven't moved or removed the distributor have you?

you could have a valve closing problem at certain rpm's or temperatures, where the intake valve is not closing properly. i'd expect that to show on the compression test, but maybe not. weak or broken spring.

you could have very heavy carbon buildup on the pistons. this can get overly hot and cause the gas to ignite before the plug fires. this is pinging or predetonation.

you could have an overly hot piston due to plenum leak. this can also cause predetonation.

are you sure it's back fire? or could it be something else?

 

Take a look at this thread sounds a lot like you problem

https://dodgeforum.com/forum/showthread.php?t=327680&highlight=backfire+hell