Why does my 40a ignition fuse keep blowing out when I try to start my car

Something that fuse powers is shorted to ground . Need to look at wiring diagrams , service repair manual , power distribution diagrams , disconnect everything it powers - one circuit at a time till fuse doesn't blow any more . Then find the short , videos on youtube showing how . EGN A ???? IGN A fuse . ENG 1 or 2
Underhood Fuse-Relay Center Fuse/Circuit Breaker
Rating
Description
ABS Fuse M4-N4
60A
Electronic Brake Control Module
A/C Fuse K11-L12
10A
A/C Compressor Clutch Relay
AUX A Fuse P7-R7
30A
Upfitter Provisions
AUX B Fuse P8-R8
30A
Upfitter Provisions
BATT Fuse M7-N7
50A
Instrument Panel Fuse Block
BLOWER Fuse M3-N3
60A
Blower Motor, IP Fuse Block
ECM-B Fuse F11-G12
20A
Fuel Pump Relay, VCM, PCM, Fuel Pump and Engine Oil Pressure Gauge Sensor
ECM-1 Fuse H7-J8
20A
Ignition Control Module, Ignition Coil, Camshaft Position Sensor, VCM, Fuel Injectors, Crankshaft Position Sensor
ENG-I Fuse L8-K7
20A
Heated Oxygen Sensors, Mass Air Flow Sensor, Exhaust Gas Recirculation Valve Solenoid, Evaporative Emission Cannister Purge Valve, VCM, Secondary Air Injection Relay, WATER IN FUEL Indicator Sensor, Fuel Heater, Glowplug Relay, Wastegate Solenoid, Crankshaft Position Sensor
HORN Fuse H11-J12
20A
Horn Relay, Underhood Lamp(s)
IGN Fuse F5-G6 (Diesel Only)
20A
PCM, Fuel Solenoid Driver, Engine Shutoff Solenoid
IGN-A Fuse M6-N6
40A
Starter Relay, Ignition Switch
IGN-B Fuse M5-N5
50A
Ignition Switch
IGN-E Fuse F7-G8
10A
A/C Compressor Clutch Relay
LIGHTING Fuse M8-N8
40A
Instrument Panel Fuse Block, Headlamp Switch
LH-HDLP Fuse F1-G2 (Export Only)
10A
Left Hand Low Beam Headlamp
LH-HIBM Fuse F3-G4 (Export Only)
10A
Left Hand High Beam Headlamp
RH-HDLP Fuse H1-J2 (Export Only)
10A
Right Hand Low Beam Headlamp
RH-HIBM Fuse H3-J4
10A
Right Hand High Beam Headlamp
RR BLOWER Fuse K5-L6
30A
Auxiliary Blower Motor Relays
ABS Relay (Expot Only)
--
ABS Warning Indicator Lamp
A/C Relay
--
A/C Compressor Clutch Coil
A. I. R. Relay
--
Air Ijection Reaction Pump Clutch Coil
Fuel Pump Relay
--
Fuel Pump
Horn Relay
--
Horns
Starter Relay
--
Starter Solenoid

You have a direct short to ground on that power feed circuit . You need to find a power distribution diagram to see what all gets is power from that fuse . Isolate the circuits till the fuse doesn't blow any more , then trace out that circuit that blows the fuse .

Which Ignition fuse ? Which fuse box is it in ? under hood , passenger compartment ?
IGN A
40A
Ignition Switch RUN, START, RUN/START/ACCY
IGN B
40A
Ignition Switch RUN/ACC, RUN/START
Could be ignition switch problem , Chevy has had problems with them .

double posted and again, no engine stated

2.2 L I4
4.3 L V6

A fuse can blow but physically look intact. How did you verify the fuses were ok? It could be that the 40A fuse 8 in the engine compartment fuse box has blown.
This supplies multiple circuits which are themselves individually fused in the consumer box inside the car.
The smaller 15A fuse 15 in the consumer box would normally blow under these circumstances but f the horn does not work as well and there are other things you have not listed that do not work like brake lights or headlights, it is definitely the under bonnet fusebox where the problem lies.
Good luck.

When the fuse blows figure out what you are doing, what switch is being pressed, then remove the needed panels to access the wiring to the switch and motor it operates, then you will find the damaged wiring and repair the short, no quick fix, just hard grunt work.

solenoid wire to starter may be shorted at starter..

There is a major electrical fault that keeps blowing the fuse. The fuse protects that part of the electrical circuit, 40 amps is heavy electrical circuit, it it wasn't protected by a fuse it car could catch on fire.
You need to get an auto electrician or your Mitsubishi service center to locate the fault and repair.
If you had a wiring diagram for your car then you can trace the wiring from the 40A fuse to the various components to locate the wiring fault or component fault.

Disconnect the cigar lighter and see if the short goes away, I will bet it does.

the windings in the coil on the compressor clutch is shorted,you need to remove the drive pulley where the belts hook on the compressor,then unbolt the 4 bolts holding the coil assy

youll have to probe that elec.circuit to find what is causing your short