1992 Mitsubishi Eclipse

Old 08-05-04, 05:03 AM
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1992 Mitsubishi Eclipse

Hey all. Friend of mine has a 1992 Mitsubishi Eclipse with a 1.8. It started missing a few weeks ago and the local garage diagnosed it as a bad injector. Long story, but somehow he wound up buying a remaned injector of the 'net for $60. I went to replace it last night, but before I did, hooked a 'noid up to the offending injectors harness and there was no signal from the ECM to that injector. Since I'm just messing around with this thing, pulled off the rest of the injector plugs one at a time and the noid lights up like it should. I even swapped a plug with current onto the non-firing injector to see what happens and the non-working injector starts working again.

So, couldn't find a short or anything else that could be not causing a signal to this injector. I imagine I'm looking at having to replace the ECM? There could be a short somewhere along the line under the dash, but I suppose going to the wrecking yard and pulling a ECM for $20 and seeing if that makes the difference, is a lot easier than crawling underneath the dash for the day, looking for a break in the wiring.

Could there be something I'm missing for this car, anybody with Mitsu experience that can point me to checking out something else that could be at fault? I hate just swapping parts and guessing.
Old 08-05-04, 05:33 AM
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basic testing...

...with an ohm meter will tell you if you have an "open" circuit. if you had a short, the injector would be spraying continuously. disconnect the injectors (all of them as they may be fired in groups) and then disconnect the connectors at the ECM...test for continuity of the drive circuit (that's the wire that goes to the ecm and provides a ground for the injector...use a wire diagram to help). if the wiring is ok...then most likely the ecm has failed. before you just replace the ecm, test all of the injectors for resistance with the ohm meter...a shorted injector will ruin the drive circuit in the ecm and while a used ecm may fix it...if the injector resistance is low, the same thing will eventually happen again. all injectors should be within .1 - .2 ohms of each other. ecm drivers don't usually just fail...they get killed.
Old 08-06-04, 04:13 AM
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Cool. So if this injector is faulty and has a short, it may have actually ruined the circuit operating in the ECM which tells the injector to fire? So, if there is low resistance at this injector, replace as well. He did purchase another injector and luckily on this car the fuel rail is extremely easy to get at. The ECM is buried in the interior, that's why I really didn't want to get in there and rip it out to test the wiring to see if there was continuity. I only had a short time to check this car out the other night. But I guess that is the next step.
Thanks for the advice. I'll see what happens when we check it out this weekend.

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