90 mitsubishi mighty max running rich!!

hell everyone,

i would like some help from you mighty max experts.

i just bought a 1990 mighty max in mint condition but its running overly rich and i dont know why.

a recent tuneup has been done before i purchased the truck. the previous owner changed the battery, distributor wires, and oxygen sensor.

the engine does have a slighty misfire and stutters at partial throttle. but it cranks up everytime and runs great.

i know it is running rich because i failed smog, i smell and see fumes from the tail pipe, and when i pull the spark plugs out they are all black.

funny thing is every spark plug except cylinder 1 is black.

i also noticed that when i put the key in ON position, the iacv is malfunctioning and moves the throttle linkage back and forth when the truck is on and running.

does that mean the IACV on the truck is going bad?

i also had another MAF so i switched it out but it didnt help with the rich condition either.

there are no check engine light as i checked with my analog volt meter.

any help will be greatly appreciated. thank you

28 views and no one has any ideas?

the coolant temperature sensor??

sorry i cant understand what you are trying to say

yes i have and that is the coolant temperature sensor.

are you sure that might be the problem?

how do i verify if the coolant temperature sensor is bad?

i just took out the ecu and its cover and noticed something that might not seem right.

it seems like there was a leakage from the battery looking thing and it leaked out.

can this be the reason why my truck is running so rich?

are these the common ecu problems these trucks have?

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so it is for sure the ecu right?

i just need to verify it is a ecu problem before i go ahead and buy a new ecu which costs a bit.

looks like one of the capacitors leaked.

Yup, your capacitor(s) leaked, which is very common for Mitsu ECU's. New ECU should do it.

thank you everyone. i will try and get the current ecu fixed or get a used one.
if anyone has another one to spare 1990 mighty max for a decent price let me know and
ill update this thread to see if it cured my problem

Google Foreign Auto Computer Repair in Zephyrhills, FL. They were recommended to me by a local Mitsu shop who has used them for years and I have had two ecu's rebuilt by them, as well as gotten helpful info from them. They will give you a price when you call them with your info and ship it back in two days. My turn around from when I sent it to getting it back in my truck was a week.