BAD stumble/hesitation

[wc701lists at bellsouth.net]

At 01:39 AM 5/27/2007, Jason Puckett wrote:
>ok, so I've had this hesitation problem for a while in my '93.  Had 
>to replace several things to get the old girl to pass 
>emissions.  After replacing EGR/BPT it got somewhat better.  After 
>having the dealer do a decarbon service, throttle body cleaning and 
>me re-installing the stock intake the hesitation got MUCH worse.

Wow, no one thing stands out.  You can grab my scan of the Nissan TSB here:
http://www.xxiii.com/~wcox/car_stuff/Nissan_B13_Engine_Driveability_Diagnosis_TSB.pdf

The TSB seems to lean towards the MAF harness being faulty.  Do you 
know anyone with an ECU to PC interface?  Data logging the ECU while 
it happens would be very useful, and may pinpoint something.

I would:
* Remove the battery terminals and thoroughly clean with one of the 
special wire brushes (even if they LOOK clean from outside).  Check 
the ground cable attachment to the body and engine block.
* Check the MAF harness for damage.  It can rub against the brake 
cylinder and piping and be cut.  93s weren't supposed to need the 
re-ground, but you can measure the delta voltage and do it if 
needed.  Ground to the side of the intake where all the other ECU 
grounds are, NOT to the battery.
* Take off  the air intake tube and check it for cracks.  It could 
have a crack that spreads open as the engine rocks around in its 
mounts, allowing un-metered air in.

That's everything I can think of at the moment that would cause 
intermittent problems...


    -Wayne  '06 RSX-S / 93 SE-R / 93 NK2k / 90 Miata / '07 Scion tC