Stalled on the way home from work

[Bobsteriffic]

So I was driving my Pathy home from work today just like any other day, and while coasting up to a stoplight the engine died. This obviously caused the power steering to go with it, but as soon as I pulled over and restarted her, she drove completely normal the rest of the way home. No sputtering, no rough idle, just died while braking towards a line of cars.

 

The only thing I could possibly think it could be is the O2 sensor. Once I was home, I unplugged the sensor and noticed only a VERY very slight change in idle, which has me thinking that this could be the culprit. I should also mention I thought I noticed her running a bit rich a few days ago, and there were also a good two stops at stoplights this week that resulted in a very rough idle.

 

Sorry if this is a somewhat sporadic post, I'm just trying to get your guys' input before I drop the $80 or so for the Bosch replacement.

 

Cheers

[snowboard419]

I would look for vacuum leaks first, it would explain the rich fueling as the o2 is seeing a lot of extra oxygen, and pushing on the brakes uses some stored vacuum from the booster and an additional leak could lead to a stall.

 

Take a spray bottle of water and spray everything in on or around the intake manifold, ON A COLD ENGINE, and see if you can hear any hissing. If you have a leak you will be able to hear it this way.

 

Sent from the twilight zone

[Bobsteriffic]

I would look for vacuum leaks first, it would explain the rich fueling as the o2 is seeing a lot of extra oxygen, and pushing on the brakes uses some stored vacuum from the booster and an additional leak could lead to a stall.

 

Take a spray bottle of water and spray everything in on or around the intake manifold, ON A COLD ENGINE, and see if you can hear any hissing. If you have a leak you will be able to hear it this way.

 

Sent from the twilight zone

Good call. I'll have to take a look at that sometime tomorrow!

[Slartibartfast]

I had a similar issue with my '95. It was intermittent, but when it was acting up, it would stall at stop signs, or even sometimes when I was slowing down for a sharp turn (which made losing power steering that much more exciting). Messing with the MAF and TPS wiring and then restarting it usually cleared it up for a while. I never figured out exactly what was behind it. I suspect the TPS or its connector was to blame--it's got a switch inside that tells the computer when the throttle's closed so the computer knows it needs to control the idle, and I suspect that switch wasn't doing its job. Then again, it could just as easily have been a problem with the idle air circuit, something in the EGR, or any number of other things. Whatever was wrong never had the decency to fail completely so I could track it down.

 

I would expect a vacuum leak to cause a constant problem, not an occasional one, but it's worth a look. Or just replace the vac lines and get it out of the way, since vac line is cheap and changing them is pretty easy. With the O2 unplugged, the ECU should change the air/fuel ratio a little, so having the idle change a little when you unplugged that doesn't necessarily suggest a problem. If you want to rule the sensor in or out, there is a test mode for the ECU where it'll flash the green LED in sync with the operation of the O2 sensor, allowing you to check whether (and how well) the O2 is working. There's a step-by-step in the service manual.

[Bobsteriffic]

Checked this morning for a vacuum seal before heading off to work, and I didn't hear any hissing. I ended up ordering an O2 sensor which should be arriving today, and I'll install that later this afternoon. I'll report back on what happens! Thanks everyone

[Bobsteriffic]

1 day later and 1 new O2 sensor installed, and it seems to be a success! Pulling the O2 sensor not only revealed a very black sensor, but it also had the original Nissan logo on the side of it, which suggests to me that it had never been swapped. She doesn't run too rich anymore, and I haven't had any rough idling/stalling. It's only been a day though, so only time will tell!

[RF600]

Idle air control valve. There is a controller for it also that could cause the problem. It can cause stalling, rough idling. They act up intermittently. If it starts acting up again, I would look at the iac and or controller.

 

O2 sensors are good for about 100k. They usually get slow as they age.

 

Hopefully replacing the O2 solved your problem.