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I have an 89 nissan 240sx.... 24 valve single over head cam. I just rebuilt the engine and upon trying to crank it Ifound that the only way it would idle was to unplug the mass airflow sensor. It still runs with the MAFS plugged in but I have to keep my foot in the gas around 3000 rpm. Any ideas what is causing this problem?....I have already tried 3 different MAFS so I dont think thats it. I also replaced the oxygen sensor...Nothing there either..... :dumbass:
 

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Sounds really painful, but go back over EVERYTHING. I would pay extra special attention to vaccuum and timing. I am working on my DE still and just for the EGR to seat properly after an hour or more of annoying work. she sure does idle alot better with a tight vaccuum. My idle would bounce at 12-15 hundred, and stutter up to around 3 grand, so I'd say vaccuum leak. put your finger up to a hose(say the fuel pressure regulator) and check for adequate vaccuum. I had around 41pounds before I rebuilt, not sure now.
Unplugging the mass air flow sensor would allow the engine to "bypass" that reading and calculate fuel and timing curves on a base map. if you are getting air into the intake plenum without it being registered by the maf, then your timing and fuel curves would both be off, causing your problem. Hope that helps.

peace
truman
 
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