Any idea's

Father inlaw gave me a 92 mighty max before he passed, had just over 130K when I got it, at 180 K the head gasket let go, removed the head and surfaced the head, valve guide seals and new lifters. truck now has 250 K and is big time trouble to crank cold, no cold start working. I have tried to scan it but the scanner says the scan port is bad. For grins I had another ECM so I replaced it with no help. What's weird as heck is if you disconnect the battery for a day or so the truck will go back to starting with the cold start mode. New Map sensor installed a few months ago. Its like the ECM doesn't recognize the engine is cold and you crank and crank till it finally runs. What do I need to check ? It reminds me of trying to crank a Mercury 300 drag race engine cause they don't have a cold start mode. Any help would be much appreciated. Paul.

your 92 has a MAP sensor? Only seen MAFS
try cleaning the contacts on the coolant temperature sensor/connector, and check the ohms same time
Idle speed solenoid connector may need atttention also

Heres what i would do if i was having your problem.

1st: check the plugs on the firewall in the engine compartment on the passenger side. unplug them and spray them with some contact cleaner.

2nd: do the same to the maf plug as above

3rd. pull the ecm, post a pic of the inside here so i can verify its the proper one and nothing is burnt.



Now for some questions.

1st. when it gets running does the idle come down once its warm or is the idle stuck.

2nd. can u visually see the throttle being actuated by the idle air control valve?

3rd. where did you get the mpa (i think you mean maf) sensor?


good luck

Quote:

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Originally Posted by finalfighter

Heres what i would do if i was having your problem.

1st: check the plugs on the firewall in the engine compartment on the passenger side. unplug them and spray them with some contact cleaner.

2nd: do the same to the maf plug as above

3rd. pull the ecm, post a pic of the inside here so i can verify its the proper one and nothing is burnt.



Now for some questions.

1st. when it gets running does the idle come down once its warm or is the idle stuck.

2nd. can u visually see the throttle being actuated by the idle air control valve?

3rd. where did you get the mpa (i think you mean maf) sensor?


good luck

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I have to stay on the gas peddle for a few minutes and it will idle on its own, once I get it to crank. #2 I replaced the idle air control valve with a known good valve. I do think its working , stays reved up between shifts, Will return to idle after few secs. Maf sensor was replaced in the air box tube, reman from Napa. I will check all my plugs, thank you. Original ECM looked great inside the plug in area. Factory original. From what I see there's two Coolant temp sensors near the thermostat housing, I have cleaned them both, brass side.

Do not use dielectric grease on any of the electrical connectors or spark plug wires ~ it will screw up all the sensor & electrical signals ~ dielectric grease is non conductive !!!!!!!
https://www.todaysmotorvehicles.com/...etween%20pins.

Use paint thinner & acid brush to clean it out of the connectors

Quote:

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Originally Posted by dash

your 92 has a MAP sensor? Only seen MAFS
try cleaning the contacts on the coolant temperature sensor/connector, and check the ohms same time
Idle speed solenoid connector may need atttention also

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The MAP sensor is year model specific to the 1990. All other EFI'ed engines use different ancillaries and ECU module. Nothing swaps between them.

Quote:

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insulates the system from the surrounding environment, preventing insulative oxide layer buildup, which increases resistance and signal loss. Although the dielectric lubricant is non-conductive, it still allows the microscopic asperities of the contacts to transfer signal and power, while filling in the valleys of the connectors where oxides and wear debris can form. Dielectric properties become especially important in multi-pin connectors, eliminating the possibility of a short between pins.

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Its perfect for the job. I use white grease and never seen any problem afterward
ohm the coolant temp sensor
throttle body clean ?
revs between shifts sounds like throttle plate not snapping back shut, or cable binding slightly
idle control solenoind air chamber gets gunked up, restricting movement. I just cleaned my Suzuki - problem solved
clean motor harness ground

Quote:

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Originally Posted by xboxrox

Do not use dielectric grease on any of the electrical connectors or spark plug wires ~ it will screw up all the sensor & electrical signals ~ dielectric grease is non conductive !!!!!!!
https://www.todaysmotorvehicles.com/article/dielectric-grease-fights-electronic-signal-failures/

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Erm, that article praises dielectric grease on electrical connectors, especially in modern cars with sensors, ECUs, multi-terminal connector blocks, etc. that may pass signals more "delicate" than the nominal 12V. The point of using a non-conductive grease is so the grease itself does not conduct any current between unrelated adjacent terminals or a ground. Any sound automotive connector will have enough firm metal-to-metal contact to displace the grease and conduct the signal.

Speaking of, on multi-terminal computer connectors and the like, I've used Stabilant 22. It's engineered to be conductive in the immediate presence of electric current like right where the actual contact points meet, filling any microscopic gaps between the contacts with a conductive fluid and effectively making it as good as a soldered joint, but otherwise it acts as an insulator. They used to run their computer at trade shows as a bare motherboard submerged in a Plexiglas tank of the stuff. One drawback: I gather it can facilitate tarnish formation between contacts of certain dissimilar metal combinations, so you only want to use it when you know the contacts are the same type of metal or a combination of metals not known to have this issue.

Quote:

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Originally Posted by geezer101

The MAP sensor is year model specific to the 1990. All other EFI'ed engines use different ancillaries and ECU module. Nothing swaps between them.

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^^
No !! geezer 101 the above post is in error.!!

I called in a favor from a friend Who now works for Alldata...
I can provide proof if need be --- there is NO map (manifold absolute pressure sensor)
on the '90 4g64 equipped (early) karman vortex mass airflow sensor
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geezer, research finalfighter thread on ecu swaps , I took that info & validated same...

All I know for sure about dielectric grease is use it sparingly ~ if anything other than a thin film is used or get it on the metal conductors IT WILL SCREW UP SENSOR OPERATIONS..! You can test my experience on your own truck ~ go ahead and lather a big glob into every electrical connector including a glob in both ends of plug & coil wires ~ if it makes your ride run better then I will stand corrected like a big DUNCE and my trust score can be F+
:grin:

Thx for the link subgothius...
Another tool in the arsenal !!!
19 years at a professional level I have used
https://img1.stewmac.com/product/ima...ch-cleaner.jpg
no oxidation on dissimilar metals...

The down side --- $ 5 an ounce, cheap price to maintain Your credibility :)

Sub, yeah I know I referenced a link touting use of dielectric grease: My experience level is obviously "beginner" compared to you guys ~ I just know that clean electrical contacts worked for my truck to run well BUT with dielectric grease in the electrical connectors it ran like crap ~ the biggest improvement came from removing the grease from two places 1) TPS throttle position sensor 2) spark plug wires ~

Not sure what GM used for waterproofing the tail light sockets & bulbs in my 1994 Chevy Caprice but it was yellowish 'n super sticky 'n gummy it kept water out of the sockets for sure & the bulbs burned bright ~

Maybe those waterproof Christmas light strings is the way to go..? Might hafta eat my words ? Thanks claych for sharing the product info, worth a look next trip to O'Reilly's
:eatcursor:

Found this on the web about dielectric grease:
https://www.google.com/search?q=does...us-revc&source

AND

https://www.google.com/search?q=wher...obile&ie=UTF-8

Scotty Kilmer says it helps conduct electricity & to lather it on every connection:

HERE (note the yellow factory bees wax looking paste on the headlight connector ~ same as my GM cars
https://www.google.com/search?q=scot...obile&ie=UTF-8

Dielectric, Definition:
https://www.google.com/search?q=diel...s-us-revc&sour

Apologies for my thread jacking :rolleyes:

All these 2.4 years I've come across run a MAFS
Mitsu farted in 1990 as it seems was a bastard year. My 90 DSM had wierd/unique electronics
Websites describe em and tell you how to repin to make 90 compatible with the 91+ models

xbox
I doubt anyone interested in proving you wrong. No point. Just sharing helpful tips
and I'd hope nobody "globs" grease into any connector. I use those 1/4" type paint brush thingys, to apply thin coat
No problem, no corrosion. Future disconnects alot easier/less effort. What more is there ?

dash, I globbed it on duh ~ dang volcano is back blowing out hot lava & smoke (VOG) hope the trade winds keep the smoke away from us here on Oahu
Aloha - George
:smokingcrack::smokingcrack::smokingcrack:

I know the 1990 is the problem child when it came to the ECU and engine ancillaries. Expensive to fix and no compatibility with other ECU controlled trucks with the 4G64. I never really investigated beyond that, and I have no idea what Mitsubishi was trying to achieve with this one year of production...