93 Ranger 2.3 4x2 (not sure on mileage probably over 200,000) that originally had codes 224 & 998 along with a miss, rough idling, and stalling issues. Came back as a bad ICM. Put new ICM on (did put new paste on) and those codes went away but now have codes 116, 129, 167, 172, and 411 which never came up previously. All codes are only present when key is on and engine is running. Truck is having a hard time starting and is backfiring when after cranking for a while. Don’t see any vacuum lines off and everything was reconnected. Previous owner replaced MAF sensor and fuel filter. Ideas?

 

Welcome to the forum

Its good to post the codes for sure, but also post the definitions with them since you most likely already looked them up
No one has them memorized, lol
116 Engine Coolant (ECT) sensor out of range - ECT
129 No MAP or Mass Air Flow sensor change during "goose" test - MAP MAF
167 No Throttle Position sensor change in "goose" test (must get at least 25% rotation) - TPS

The above all use Reference Ground from the Computer(PCM), you need to test if that is working, Grey/red stripe wire
This wire is also at the OBD1 test connector, make sure you didn't leave jumper connected, or a wire came loose from the back
Give the wiring harness a look, move things around a bit to see if you see any frayed or bare wires

172 (R,M) Oxygen sensor not switching - system is or was lean - Single, Right or Rear HO2S - Fuel control
411 (R) Idle speed system not controlling idle properly (generally idle too high) - ISC

Both indicate air leaks, or misfires
After engine is warmed up and idling, unplug the 2 wire connector on IAC(idle air control) Valve, it will close and RPMs should drop to 500 or so, engine may even stall, either is GOOD, it means no air leak.
If idle stays high then there is a leak, for sure

224 (M) Failure in ignition coil primary circuit - Ignition Systems
998 (R) Did not pass Key On Engine Off test yet (Get 111 in KOEO first) <<< ignore until all other codes are cleared


The white paste is for the heat sink, transfers heat better, but also isolates module from engine ground

The ICM module needs a good case ground, usually upper left bolt is the ground for these
Code 224 can often mean ICM ground is intermittent, not a bad module
Many have run a separate ground wire to the upper left bolt with good results


The 1989 to 1994 2.3l Lima engines only use the exhaust side spark plugs and Coil Pack for startup, intake side is disabled, this gives the 4 exhaust side spark plugs a hotter spark for cold start, when starter motor is active battery voltage, so spark voltage, is down at 9.5-10volts

Double check the spark plug wiring on exhaust side, trace each wire back to coil pack and make sure it is in the correct spot

The intake side spark starts when engine is above 400RPM, just FYI