Oxygen Sensor

2001 Gp Gt With 65000 Miles
What Is The Best Way To Tell If You Need To Replace An O2 Sensor?
My Car Sounds Like A Vacuum When I Start It Cold. It Will Leave A Cloud Of Blueish Smoke When I First Hit The Gas Then I Drive It A Few Miles Or Less And The Vacuum Sound Goes Away. It Also Seems To Run Better When It Is Colder, Alot Better Than When Hot.

Unless the 02 sensor is giving odb-ii DTC error codes and triggering a SES light it is hard to tell. They can degrade to as low as 60%. Low fuel economy can be an indicator. One thing you can do is remove them and visually inspect for carbon. Your problem doesn't sound like an 02 sensor. Until the car warms up fully and enters closed loop mode the 02 sensor is really not being used.

The blueish smoke doesn't sound good and indicates oil is being burned. In a worse case scenario, you might have a problem with the upper/lower intake manifold gaskets. Check your engine oil and coolant for cross-contamination and excess consumption.

Where is the vaccum sound coming from? What part of engine?

That sound you're hearing is the EGR valve. It stays open to recirculate hot exhuast gas back into the engine until the car hits a certain temp.

Another possibility is that the cat may be starting to block up. The noise you hear may be coming from it since the exhaust gases are trying to force their way past the blockage. Just another idea!

If he lives in a green state it could be the secondary air pump. It is an electrical pump motor used for emissions control. Check for the RPO NC8 on your SPID label located in the trunk on the back of the lid.

There is a GM TSB out on secondary air pump problems.

BTW - The EGR valve does not start recirculating exhaust gases until certain engine parameters are met. The ECT - Engine Coolant Temperature must be greater than 75 degrees C or 167 degrees F. If an EGR is operating before the engine is fully warmed up there is a problem.

sorry i forgot to mention the vacuum sound is coming from the intake. it sounds like that regardless if the regular air box is on there or if the kn intake is on there. it just sounds a little louder.

wouldnt the car always be smokeing if it was burning oil? that and it dont seem to be loosing any oil. it almost seems like the sucking noise or vacuum sound and the smoke are tied together. i just flushed my radiator and it didnt have any oil residue in it. there was also something done due to a tsb on the intake within the past 2 or three years. and it has done it for almost that long. i know it didnt do it when i bought the car at least which was 2 years ago.

sorry i forgot to mention the vacuum sound is coming from the intake. it sounds like that regardless if the regular air box is on there or if the kn intake is on there. it just sounds a little louder.

wouldnt the car always be smokeing if it was burning oil? that and it dont seem to be loosing any oil. it almost seems like the sucking noise or vacuum sound and the smoke are tied together. i just flushed my radiator and it didnt have any oil residue in it. there was also something done due to a tsb on the intake within the past 2 or three years. and it has done it for almost that long. i know it didnt do it when i bought the car at least which was 2 years ago.

Ok, got it. From the intake manifold and prior intake work was due to the GM TSB. Yeah, that TSB concerning the UIM problem and the EGR stovepipe has been out for quite a while. So the noise has been there since that work. Maybe the job wasn't done right or since there is signs of oil being burned off check out the PCV valve. Make sure the MAP sensor retainer that goes over the PCV has the spring. Also, there is a big o-ring seal that must be present and the smaller one on the PCV valve. Oil could be being drawn in from the PCV area. Might consider replacing the PCV valve too.

Ok, got it. From the intake manifold and prior intake work was due to the GM TSB. Yeah, that TSB concerning the UIM problem and the EGR stovepipe has been out for quite a while. So the noise has been there since that work. Maybe the job wasn't done right or since there is signs of oil being burned off check out the PCV valve. Make sure the MAP sensor retainer that goes over the PCV has the spring. Also, there is a big o-ring seal that must be present and the smaller one on the PCV valve. Oil could be being drawn in from the PCV area. Might consider replacing the PCV valve too.
thankyou ill have to try the pcv valve. i do remember my mechanic checking out the intake and he even said he couldnt see any evidence of something being wrong with it.