Welcome Visitor! Please take a few seconds and stickboy697
Member
I have a 1997 Ranger 4x4 with an M50d and 4.0. I purchased the truck and previous owner stated that he had found it was dead on #1 cylinder. I started the truck and drove it onto the trailer and it was missing while it ran there was no CEL. I bought the truck for my son, as I had a 1997 4.0 that came out of my 1997 that ran great when pulled but i removed it and replaced Engine, trans and transfer case in my truck when i swapped from auto to Manual due to failed Auto. So i know that the motor i just put into my son's truck ran with no issue. Installed motor into truck and attempted to start it, no luck. Determined that due to wiring harness being from Automatic transmission had nothing to plug into to take care of neutral safety switch. Removed harness from the replacement engine and installed original harness for the truck. Truck started and was missing and then began to backfire and idle roughly. Thought that possibly was stale fuel as it had set for at least 3 months. Took it to town and filled from 1/8 tank to full with fresh premium fuel and some sea foam. Nothing changed, but there was a CEL and codes indicated Misfire on cylinder 1and an malfunctioning O2 sensor. (found that O2 sensor had missed getting plugged in after install. Hooked up and cleared CEL) . Put spark tester inline between wire and spark plug and have great strong spark. Ignition box installed on engine was known good on replacement engine. Removed Plenum and removed and replaced with full set of newer fuel injectors that all tested at 16.3 ohms indicating good. Checked injection harness for any indication of exterior damage to wiring or shorting nothing noted. Reinstalled Plenum with new gasket above and below fuel rail. Reconnected all wiring and vacuum lines and started truck. Still backfiring and missing. Truck idled for a short time, backfired, and then died now not starting. I suspect Wiring harness. Before pulling Harness and replacing with one from salvage yard or pulling mine and removing corrugated loom and checking continuity of each at connection from plugs at injectors and at the ECM side. (Inspected ECM pins to ensure none had been bent or damaged during install and found all in good condition.) I'm stumped and would appreciate input. Have done 8-10 engine replacements and swaps, so definately not a pro, but not a complete newb either. checked connections and grounds and still left scratching my head.
