Backfire on deceleration?

royslead said
Not likely the fuel sync. I've corrected many of those, back in the day; none of them caused an issue like this. Impossible? Well there's always something that teaches us something new...On that note, how can you not get a hold of a scan tool for OBD-1 ? Chrysler used that same connector from the '80's, up until '95. I suppose, being in Ontario limits your availability, especially, if you're in a remote area. I would think maybe an older repair shop would have something. A lot of aftermarket scan tools had that capability, maybe you can find one, or even better - find an old Chrysler DRB II, or III. They are out there.

Thanks for confirming my thoughts on the fuel sync. In your experience, what symptoms would a bad sync display?

It's not impossible to find a scan tool. I haven't been to see my usual mechanic since I completed the swap, I'm sure he would have the adapter for his snap on tool. I've put a bit of effort into finding a DRB but many sellers over value them, in my opinion.

The car runs friggin awesome, aside from the backfiring on deceleration, so I'm not worried about it. I was also thinking that I don't get any backfiring below around 2400 RPM, it's only when I back off at highway speeds (A904 with 3.23 gear with 26" tire, so about 2600 rpm at 65 mph). So maybe the backfiring isn't entirely abnormal, considering the trucks that these engines originally came in had the 46rh / 46re with a 0.69 overdrive, so there wouldn't be a lot of decelerating above 2400 rpm. And with the stock Y pipe and big huge stock muffler it might not be so obvious as it is with my long tube headers, 2.5 inch dual exhaust, and performance mufflers.

Anyway, I'm putting a 46rh into the car next year, so we'll see what happens with the backfiring when the revs are way lower on deceleration. And I also picked up an entire OBD2 harness, intake with all sensors and injectors, and computer, so if I want the ability to put a tune into it for further performance mods I can swap to OBD2. But I just got it running a couple months ago, and again it's running pretty good on the old OBD1 setup now, so I'm not going to punish myself with a rewiring job just yet.