Howdy, My 95 LT1 with 45k keeps killing the O2 sensors. Chevy dealer
has replaced sensors,plugs, PCM, optispark at various times to try to solve this
problem. O2's last about 800 miles. Any brilliant insight I can give the dealer
before I have to dump my beautiful ragtop?
-Mike in Kansas

 

any chance your running dexcool?

 

Not a chance.

 

How does it kill the sensors? Are they becoming coated with carbon? Are they burning up? What symptoms appear that lead to replacing the sensors?

BTW, welcome to the forum!! :cheers:

 

All kinds of silicon sealer, copper grease, etc can kill a sensor. Can you think of any where that sort of stuff is getting in your engine?, - Maybe copper grease on the plug threads, throttle butterflies or W.H.Y.

 

How do you know they are bad? Any scans of the car? I don't think anything would kill the sensors that quick.

Please explain why you think they are going bad. If its your running too rich, I would think that your injectors are sticking or a vacuum leak is present causing the MAP sensor to give bad readings, the MAT sensor is bad, MAP cars fuel calculations heavily depend on that MAT sensor for fuel corrections in different operating enviroments temperatures. If any of these items are bad then your fuel curve will be all hosed up and it might appear that you )2 sensors are not doing what they are suppose to be. Also is your FP regulator right. If your running really rich at idle, then you may have a bad vac line or a faulty/stuck regulator that is not throttling back the pressure at idle. Here is how it should work: At idle you are drawing a large vac, this reduces the FP. At WOT there is no vac and the fp is highest. When you remove the vac line when setting your FP, you are really setting it for WOT conditions. Then when you hook the vac line back up at idle you see the FP reduce a few PSI.

If you would like to see this actual happen in real life, here is a video of a vac guage hooked to my car while making a WOT run on a dyno. We were doing this here to see if the MAF meter was causing any significant restriction in the air intake system. Here is the clip:
http://temp.corvetteforum.net/c4/ski...ac_guage-1.wmv

 

Thanks for responding. The check engine light comes on and when I run the error codes, they are (trying to remember) H063 & 64, which point to the sensors. carbon out tailpipes. carboned up plugs, etc. They change the sensors and plugs and it runs well until they clog up again. They told me the intake was leaking, would that be the vacuum leak you are referring to?

 

if its leaking , then coolant and/or oil can be sucked into the cylinders. not sure about the oil, but coolant will kill the o2 sensors quick.

 

Hmm. I thought a leaking intake would only be a vacuum leak, but then, I'm not a mechanic.

 

Has the Mech ever scanned the "new" sensors? i.e. Is the O2 sensor signal even getting to the ECM? (Is the sensor signal bad or is a bad signal ruining the sensor?)

Many things can kill an O2 sensor.

Are these single wire, 3 wire, 4 wire?

 

I would go over the intake with Ether and see if you have a vac leak anywhere that might be causing you to run overly rich. Check your rad level, but you sound like you keep a pretty close eye on things, and if it was coolant ruining the sensors, I would have thought that you would have overheated by now.

Have him check the wiring from the sensor to the ECM, something is not right with the wiring or fuel delivery etc that is causing them to flake out.

Do you have any scans of the car. I can tell a bunch of information from them. See if you can get some for me look at. Make some with the new sensors and then some as they go bad, if possible.

You are not running any kind of additives in the fuel are you? About the only thing I know of that will kill an O2 sensor right away is lead, and that even takes some time.

:crazy:

 

They told me I had an intake leak right after they replaced the Optispark.
Of course now I know the Optispark wasn't bad. We will be having a talk about that at Chevy. They are saying the waterpump also has a slight leak.
What do you think? Have em reseal the manifold and put a new pump on?

 

Chevy now claims the oil from the K&N is getting on the MAF.
Told em to replace it with a stock filter. Ever heard of this problem, or
are they full of zee caca?

 

I've heard of the oil from the K&N FILTER can cause build up on the throttle body, so there can be build up on the MAF.

 

I have sent K&N a message, will advise if they answer it.

 

LT1 intake is a dry intake-- no coolant runs within it.

 

K&N oil on the MAF & TB is a pretty common occurance, but it stops after a couple of thousand miles and it cleans up with Throttle Body cleaner. It's just a light oil, nothing exotic, certainly it will not kill an O2. Worst case, get a K&N cleaning kit and apply a lighter coat of oil (sometimes the factory is over zealous with the spray).

When did this start happening? Did you do anything prior to it happening the first time?

If the dealer changed the Opti and didn't recommend doing the pump at the same time, shame on them. I hope this is all under warranty.

Sounds like you need to take BS flag with you to the dealer. Throw it everytime they open their mouth.



[Modified by John Row, 4:16 PM 6/19/2003]

 

They're full of zee caca for the most part. A brand new and/or over-oiled K&N can indeed cause some micro oil droplets into the air blast, which would coat the MAF, BUT-- the '95's MAF has a burn-off relay that kicks in when you shut down the motor and is intended to be a way to burn off contaminants from the wires/diodes of the MAF. An oil fouled MAF wire would make the car feel sluggish and generally run less than optimally but it in no way could cause the ECM to freak out enough to set the mixture so screwy as to kill O2 sensors in any amount of time, much less 800 miles.

Typical dealer service shop response: When all else fails, find a non-OEM part that is installed and blame the problem on that :rolleyes: :rolleyes:


[Modified by Lone Ranger, 6:18 PM 6/19/2003]

 

We'll see if they are right in about 789 miles.

 

The tech said the MAF readings were 10 something and after he cleaned it it was 7.1 or something