Engine Control Module

[CROW]

Short version of the story. Mitsubishi Eclipse, 1991 model, would die. Had spark and compression after it died, but would not start. Thought it was the fuel pump but it has good fuel pressure. Local mechanic (who is really,really,really proud of his work) says the computer is bad causing the intermittent condition. Odd, told him to put it back together and it runs OK now, no check engine light and no computer codes, hasn't died in last 10 running sessions. Think he is wrong and would like to know how to tell definitively whether the ECM is bad or not. How do you tell if an ECM is bad? Can anyone help? Thanks in advance.

 

[illflem]

Scan tool is the way. I'll bet the only problem was a bad connection that was made good while fooling around, it very well could come back.

 

[docdyno]

A scan tool will not always show an engine controller failure. Some codes like EEProm failure will not display with some scan tools. Traditionally drivability problems sort out like this. Fuel system, fuel related issues 50%, Sensor failures 15%, wiring system faults (connectors, corrosion, BAD GROUNDS, shorts/opens) 30%, Related electrical issues (electrical spikes, overcharging, etc. 4% ECM actual failures (documened) less than 1%. Lots of ECM's get replaced, few are actually BAD.

 

[Shovelhead]

For what it's worth.....

My old '90 Dodge gasser would cut out on occasion, no warning. This began 3-4 months after the Stealer replaced my ECM because the built in voltage regulator died.

The "Mechanics" had in in and out of the shop for over two months attempting to find the cause.

I picked up the truck and it did it again. Popped the hood and started shaking wires to find the loose connection.

Within two minutes I found it... ... the morons never tightened the hold down bolt for the main ECM plug. (Yes I went back and got a refund for the "bad ignition coil, plug wires, distributor pick-up module that they replaced to fix the problem")



Loose connections are probably the leading cause of "electrical component failures", if they can't find the trouble, replace parts until it goes away, or the customer runs out of money or patience.



Sorry to be so long winded, but 4 years later it STILL ticks me off. :-{}