[daveyboy43]

1999 Malibu that was running very bad with an awful smell coming from exhaust.Turned out that problem was a bad fuel pressure regulator which I replaced. After that was done the car started right up,idled fine,no smell or smoke from the exhaust and it ran great.However after about 15 minutes or so the car stumbled and then stalled and wouldn't start up.After a couple minutes I got it started but it only ran a couple minutes and stalled again. I parked the car and returned to it a couple hours later and it started right up and I was able to drive it home with no problems only 10 minutes away. The next morning I started the car with no problem and it ran fine while idling in the driveway for about 15 minutes and then it stumbled and then stalled out and it wouldn't start until the engine cooled. Someone has suggested that the oxygen sensor may have gone bad from the engine running rich from the previous problem, but I'm getting no codes.Does anyone have any thoughts on this or any other suggestions.

 

[SuperSS27]

Sounds and Smells like your Catalytic converter is plugged up, or your O2 sensors have gone bad. Its either one or both of those.

 

[daveyboy43]

The smell and the smoke is gone now that the fuel pressure regulator is changed. I'm thinking the O2 sensor is bad from the car running so rich. Any tips on getting the O2 sensors off as they are really on there and I can't budge them.

 

[Canyonaro]

The smell and the smoke is gone now that the fuel pressure regulator is changed. I'm thinking the O2 sensor is bad from the car running so rich. Any tips on getting the O2 sensors off as they are really on there and I can't budge them.

When I changed the front and back ones on my VW a few years ago, it was easier to unbolt the cat from the exhaust and then clip the wires and work it out. With the cat out I was able to get to the front one easier as well. Either way the configuration is, you usually need a nice long driver and some power behind it. They are supposed to be coated with antiseizure type compound, but sometimes it just doesn't work.

 

[daveyboy43]

How hard was it to get the cat unbolted at the manifold.The bolts look in great shape but they lool like an s.o.b. to get ahold of and get some leverage behind. I actually have a new oem bolt on cat,but I didn't like my chances of getting it off.

 

[daveyboy43]

I changed the O2 sensor and all seems well. I just have 1 question. After I changed the sensor and ran the car for 15 minutes it stalled and I thought here we go again,but it started right back up and ran for 45 minutes with no problem and I later took it for a 30 minute ride again with no problems. Why
would it have stalled that first time after the sensor was installed but never acted up after that. Should I still be concerned?

 

[mbukukanyau]

1999 Malibu that was running very bad with an awful smell coming from exhaust.Turned out that problem was a bad fuel pressure regulator which I replaced. After that was done the car started right up,idled fine,no smell or smoke from the exhaust and it ran great.However after about 15 minutes or so the car stumbled and then stalled and wouldn't start up.After a couple minutes I got it started but it only ran a couple minutes and stalled again. I parked the car and returned to it a couple hours later and it started right up and I was able to drive it home with no problems only 10 minutes away. The next morning I started the car with no problem and it ran fine while idling in the driveway for about 15 minutes and then it stumbled and then stalled out and it wouldn't start until the engine cooled. Someone has suggested that the oxygen sensor may have gone bad from the engine running rich from the previous problem, but I'm getting no codes.Does anyone have any thoughts on this or any other suggestions.

perhaps the dealer might help you

 

[nicolet]

I changed the O2 sensor and all seems well. I just have 1 question. After I changed the sensor and ran the car for 15 minutes it stalled and I thought here we go again,but it started right back up and ran for 45 minutes with no problem and I later took it for a 30 minute ride again with no problems. Why
would it have stalled that first time after the sensor was installed but never acted up after that. Should I still be concerned?

I'd remove the exhaust (temporarily) and see if the issue exists still...to rule out a plugged cat converter...

 

[kw02]

I'd remove the exhaust (temporarily) and see if the issue exists still...to rule out a plugged cat converter...

Does a catalytic converter that's clogging enough to stall a motor cause a change in the exhaust sound that could be heard as it starts blocking the exhaust stream more?

 

[nicolet]

Does a catalytic converter that's clogging enough to stall a motor cause a change in the exhaust sound that could be heard as it starts blocking the exhaust stream more?

Yeaaahhhh, I think so???????

 

[daveyboy43]

But the car ran great and never stalled out after the initial stalling right after the O2 sensor was changed. If the cat was a problem before after 15 minutes wouldn't it still rear it's ugly head again after the same period of time? The car ran until I shut it off and no problems.Could it have something to do with the computer resetting and realizing the problem was gone or something like that.I've heard that when your car has a problem sometimes it takes a little time for the computer to learn that and reset. Any ideas on that?