Nissan Repair: Intermittent Rough Idle, nissan sentra, service engine soon light

Question
I have a 2002 Nissan Sentra with 97,000 miles. It has been having an intermittent (I believe) misfire problem. It happens when it is wet outside, but occasionally happens when it's not. The Service Engine Soon light blinks on and off but doesn't leave a code. At idle, it runs really rough when it is doing this, and you can feel some hesitation when going at speed and downhill. I just got the cranksensor replaced. When the rough idle does happen, it's more violent than before I had the cranksensor replaced. Some days, it runs fine with no blinking SES light, no rough idle. I thought it was the rain, but sometimes it even does it when it's clear. :( I'd be very happy if you had any idea?? Thanks.

Answer
Hi Linda -

If you haven't already, first thing I would do is do a complete tune up - dist cap, rotor, plug, even wire set. Also replace the ignition module in the distributor.

It sounds like the car is missing under certain conditions, and the tune up may help that.

I think the reason your SES light blinks is during the miss, the exhaust will read rich, the O2 sensor picks that up and signals the CPU to turn the light on.

try that tune up first, and then get back to me -

aloha
calvin