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Discussion Starter #1
My wife's 97 Altima just started running poorly. Only rough below 1500 rpm. Gas mileage is the same. Runs fine on the highway.

Check engine light comes on after about 3-4 minutes. It flashes randomly (12 times, then solid, then 74 times, then solid, ...). Codes are "knock sensor/condition" and "misfire in cylinder 4".

Replaced plugs and wires. Ran Sea-Foam (only cleaner I trust) through it for 2 weeks now.

Anybody know what impedance should be on the injectors? Any other thoughts?
 

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the impedance should read 11-12 ohms at 70 degrees but no more than 13-13.5 at running temp.
I actually had the same type problem and had purchased a set of injectors from Motor Man Fuel Injection and now the car runs like new.
 

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Thank you sir. Hadn't found that in the Haynes yet. I'll keep everyone posted as things progress.
 

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Injectors are all 11.2 - 11.6 ohms. Cleaning battery terminals right now (you never know, right?). Checking the impedance of the knock sensor next, since that is the code popping up. But why would the misfire just be on cylinder 4??
 

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So if I would have followed my own advice and looked at the cheap easy stuff first, I would have done this:
Clean the corrosion off the battery terminals.

That fixed the misfire issue. Still sputters a bit, but we're working on that with Sea Foam.
 

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dont be surprised if the seafoam wont fix it. fuel additives are arent very aggresive cleaners and will cause more harm to your injectors coil than good.
eventually it will eat the varnish coating off the coil winding causing a short in the injectors.
 
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