1991 Nissan 240SX #4 fuel injector gets no signal

1991 NISSAN 240SX
147,000 MILES • 4 CYL • 2WD • AUTOMATIC
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DADDY WARBUCKS
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My car started with a rough idle 2 days ago. brought to mechanic and said its misfiring but went through the checklist to start tuneup and said sparkplugs, wires etc ok and that fuel injectors 1,2 and 3 are recieving signal but not #4. He said its car's computer but doesnt seem to have much experience here so I want second opinion before I start buying stuff.
Mar 5, 2010 at 3:19 PM
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2CARPRO JACK
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First be sure there is power to teh injector.The computer uses ground to control it, not power. All injectors should have power all of the time.If so then use a meter to check continuity on the trigger wire for that injector.If the wire is good and there is power, the computer is most likely bad
Mar 5, 2010 at 5:10 PM
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DADDY WARBUCKS
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I have seen a few of the computers for the year and model on ebay. If it is the computer can I just bascially pop it out and put the replacement in without any special tuning etc?

also, if it is the computer, generally (since I know you cant be sure) does it get progressively worse where other areas that are controlled start to be affected or can it simply stay like this for a while like a bad idle?
Mar 6, 2010 at 1:01 PM
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2CARPRO JACK
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It is hard on the engine to run it when misfiring like that.It adds alot of vibration/load to the bearings and other internal parts.Not ot mention it possibly could damage the cat converter from the mixture being off so far.On a91, you should be able to just "plug-n-play" on the ECM, shouldnt require any preogramming, but you need to be sure to get the right one for your car
Mar 7, 2010 at 8:46 AM