advice on idle problem--long

[wmc2004aug at bellsouth.net]

At 01:29 PM 11/29/2004, dmh wrote:
>Three or four months back it developed a slightly rough idle.  Just after
>the first symptoms appeared, I had to loan the car temporarily to my
>son.  I just got the car back last week and the problem is now so bad that
>I can barely drive the car.

>1.  Engine "cold" (I live in a warm weather climate):  After starting the
>car if it is put in drive or reverse, the rpm will fluctuate wildly
>between a few rpm to 1-2K rpm before stalling.  The only way to keep the
>car from stalling when in gear is to give it lots of gas.  Even then, it
>is touch and go.

That makes me think vacuum or bad MAF (or its wiring.)  Also, getting the
idle speed & ignition timing set with the ECU in proper "work support mode"
can do wonders...  but it sounds move severe than that.

>2. Engine is hot:  Very rough idle (nearly stalls), especially when in
>drive or reverse with the brake on, such as at a stoplight.

Hmm, have you measured the car's voltage?  (s.b. around 13.8V)  An
alternator putting out zero or too much voltage can foul stuff up.  You
mention "with the brake on" -- the power brake booster is vacuum
operated;  could it be bad or have a leaky hose?

You can check my scan of Nissan's TSB on engine problems at:
http://www.xxiii.com/~wcox/Nissan_B13_Engine_Driveability_Diagnosis_TSB.pdf

    -Wayne    '93 SE-R / '93 NK2k / '91 NX2k / '90 Miata