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Nissan Repair/1991 300zx TT EFI harness replacement?


Jeff wrote at 2006-06-27 16:16:43

I know this post may be out of date, but I thought I would share my similar experience in case you (or someone else) are still looking for a solution.

I am having a similar problem with my 93 300ZX TT.  One of the fuel injectors went bad, causing the engine to run exrememly rough.  The dealer said that all of the injector connections were corroded and that all of the injectors and injector connectors needed to be replaced.  The total was going to be about $3000.

I took it apart and sure enough, all of the fuel injector connections were corroded.  Most of the other electrical connections looked very clean, however.  I did some research and now think there is a design flaw in the way Nissan designed the 300ZX fuel injector drive circuitry.  On 90-93's, 12V is always applied to injectors, even when the car is off and parked in your garage overnight.  It appears that over time, small leakage currents may cause the connectors to corrode and eventually create an intermittant connection.  The connections at the ECU, under the passenger floorboard, look clean sith no signs of corrosion.

If the fuel injector connectors are the cause of your problems, you don't need a whole new harness, you can splice in replacement connectors for about $36.  The fuel injectors themselves, however are a different story.  They are $171 each.  You do not need to remove the engine.  You can either remove the plenum for easy access or dremel the plenum to get the fuel injectors out.  Go to and look in the tech pages for some excellent articles on how to do it yourself.

Send me an email if you have any questions.

Regards, Jeff

Rich wrote at 2006-08-27 03:08:34
the engine wiring harness can be replaced with the engine in, though it would only be possible if the plenum is removed. The bigest pain is getting the threw the firewall and getting to the clamps were the harness attaches to it.If you are not doing the work youself I would NOT take it to a dealership, I would find a shop that specializes in 300Z's

good luck

yolanda wrote at 2014-10-08 01:52:42
hi ,i had the same problem try Doug at z fever in Tampa.Fl. I purchased a brand new engine harness wire for about 500.00 and my car runs like a dream. He probably has what you need and if they don't they will repair the connections on your existing harness. They will ship also. Good luck!

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