'98 V70 GLT Intermittent Surging/"Coughing"

[abscate]

My gut says this is electrical but the gut can often let you down troubleshooting.

[sleddriver]

Start with the wiring from the sensor connector to the sensor itself.
Read: viewtopic.php?f=1&t=75805

[bmdubya1198]

I agree, I think this is definitely electrical. My cousin (who knows his stuff... used to work as a tech for Hendrick Motorsports) told me the same thing... you never know with sensors. They could act fine when you test them, but you never know until you replace them. Hopefully I'll make my way to the junkyard tomorrow to pull a CKP sensor or two to fix this.
I decided to put the car back together today and fix the torn insulation on the sensor wire to see if it improved anything. I am 99% sure that the crank sensor is the problem. When I put is back together, I made sure to route the wire for the sensor away from the spark plug wires, and moved them a little to make sure they were as far away as possible from each other.
After that, the car started right up. Ran great. I took it for short drive around the neighborhood and it was doing great. I took it on a longer drive after that and it coughed a few times, once while braking at a stop light and another time while I was stopped. Maybe one or two small episodes while driving. Interestingly enough, I took it on the highway and cruising between 60-70, it didn't cough once. It's funny, because most people with this issue had the symptoms especially while driving on the highway.

[sleddriver]

Sounds good! There are two parts to this fix:

1. Ensure the sensor wires are not corroded, the plugs/connectors are clean & shiny and ALL insulation is in place. Both for crank & camshaft position sensors. The two sensor wires should be carefully twisted together to minimize stray noise pick-up, then protected with either heat shrink or tape.

2. Ensure both of these wires are as far as possible from both the coil wire & ALL plug wires. They should be oriented 90 degrees from any/all high energy coil/spark wire to minimize noise/spike pick-up.

[bmdubya1198]

Finally made my way to the JY this morning and grabbed a crank sensor. So far, it's running great. No problems so far, driven about 30 miles on this sensor.