# Horrible miss high idle



## Hardbodykramer93 (Nov 12, 2015)

I have a 97 Nissan hardbody that at idle jumps from 1500 rpm to 2000 rpm replaced mass air flow been to plenty mechanics pretty lost anyone with ideas would be awesome


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## Hardbodykramer93 (Nov 12, 2015)

I have a video but it won't let me post it by the way


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## jp2code (Jun 2, 2011)

It sounds like the ECU is in fail safe mode (i.e. limp mode).

If that is the case, you can just pull the codes to discover where the offending area is.


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## Hardbodykramer93 (Nov 12, 2015)

Yea but the check engine light isnt on and when I even hooked up a scanner it showed no codes :/


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## rogoman (Dec 16, 2004)

Check for a major vacuum leak in the intake system. Attach a vacuum gauge to a full vacuum source. With the engine fully warmed up, the reading at idle should be 18 - 20 InHg. At 3,000 RPM, it should be 21 InHg. If readings are under 18 InHg, check the intake manifold nuts to make sure they are tight. The gasket may have failed; spray a water mist at the gasket to see if the gauge reading changes. Also check the intake plenum bellows at the throttle valve and at the MAF for cracks or loose clamps.

If you have a bad miss, then you may have one or more fuel injectors that are not firing. You can use a "noid" light probe on the signal wire at each injector to see which one is not firing.


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## tomit (Jul 2, 2004)

For the '95, a bad EGR part (can't remember which) caused high idle and some missing.

Tom


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## Hardbodykramer93 (Nov 12, 2015)

Ok so I can up with the issue a mixture of my dang throttle cable sticking and a bad mass airflow sensor but does anyone know how to reset the computer after I replace the mass air flow sensor?


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