Cadillac Repair: problem with firing order/timing, chrysler engine, catylitic converter

Question
I have a 1992 sedan deville,which we recently changed the engine out to a 1995 4.9l(same engine that was in the car just different year)the gentlemen,so to speak, that performed the engine switch had every wire wrong in the firing order wrong except the #7.he turned the distributor until it ran,although had been running hot.not over heating but hot.we were unaware of the wiring mix up until we tried to change the wires today and realized that is 2-4-6-8 had 5-3-6-7 and well you can see where this went.we switched them to proper order 1-8-4-3-5-6-7-2 and now car is back firing and catylitic converter is so hot it glows red,before we switched the wires car ran fine but had a sputter if you barely touched the gas pedal,if you put your foot into it she went!it makes no sense to me at all that it ran with all wires wrong but 2. so now all wires are right and it runs hot and is back firing through throttle body and exhaust,idling rough,and if you put it in gear it stalls immediately.is there a simple solution? if so what?
PLEASE HELP!

Answer
Hi Chris,

     This sounds like a similar problem I had when I installed a Chrysler engine in place of the same size but Mitsubishi engine. They both use the exact same engine but the distributors are different electrically.

     So to recap...both firing orders are the same just like you sent me. The wire terminal notch on the cap is aprox. at the 7-8 o'clock position or 40 degrees from the centerline when installed correctly. Timing is adjusted by jumpering A-B on the ALDL connector which is below the radio area under the dash through a rectangular hole and set to 10 degrees BTDC. The front engine bank is 1-3-5-7 and the rear is 2-4-6-8 with cylinders 1&2 at the serp belt end. There could be a problem with the distributor. If you didn't use the distributor from the '92 I would try it and see if it makes a differance. The fireing order goes counter clockwise around the cap.

      You could have a problem with overfueling due to faulty injectors or a fuel pressure regulator that has a hole in the diaphram allowing gas to get sucked into the engine through the vacuum hose. Installing a fuel pressure gauge could show leaking injectors if the gauge drops after the key is turned off instead of holding.

      Hooking up a scan tool to check the sensors might find one that is giving bad readings. MAybe it isn't hooked up electrically or vacumm wise. Also make sure that the negative battery cable attaches near the starter and is clean and tight.

     If all things check out then haveing your mechanic look at it would be needed otherwise maybe the engine has a defect that is allowing it to run that way. Let me know if you need anymore help. Bill