I recently put a remanufactured lt1 into my 95z28, when I picked it up from the mechanic the ses light came on when the fans kick on and then go on and off sporatically, also there is a loud obnoxious banging in the exhaust that was never there with the old motor, the mechanic said it was something broke in the cat rattling around in there, yeah right, I can tell that it is excess fuel being burned. It will usually calm down while driving but as soon as I stop it will start doing it again whether the motor is hot or cold.

Sound like the o2 sensors? Where can I buy them and what do I search for and any tips on changing them out? Where are they?

Thanks guys!

 

Well I don't know about the noise you are hearing so I won't say anything about it.
o2's can be picked up at your choise of auto part stores like: Auto Zone, Napa and so on.
Make sure you get the good ones!! They are pricy by you wont be replacing them in a few months.
The are located in front of yor CAT up in the Manifold, Just disconect them and use a open end wrench to remove them I think it's a 3/4 or 7/8.
What ever you do don't touch the ends of the new o2's with your fingers, they don't like that.
You can use a SMALL amount of Anti Seze on the treads to help prevent rusting.

 

I just can't figure out why they would go bad after a new engine install?? Would he have to touch them or something?

 

Not positive about the 95, but on the 96 Z28, the front O2s are installed onto the stock exhaust manifolds. So, if your mechanic did an engine swap, he probably yanked the engine out with the manifolds installed. Do you know if you re-used the old O2s or had new ones installed? Either way, the O2s are on your manifold, so I wouldn't be surprised if they got damaged during the engine swap.

As for the popping, that's probably unburned fuel finally igniting in your exhaust. That could happen if your running rich...which could be due to a bad O2.

If you've had the original O2s, you should go ahead and change them out. Yep, definitely get the AC Delco ones...don't mess with other brands.

 

http://www.partsamerica.com/ProductD...pe=291&ptset=C

Is this correct? I guess I need to buy 2? It says 2 required but I'm guessing it's 62 bucks for 1?

Thanks again.

 

Have you not yet done a PCM scan to pull the codes?

 

What do I need to do a pcm scan?

 

Ya you will need 2 o2's at 61.00 each

 

AC-Delco's can by had for about half that much from one of these guys.

http://shbox.com/1/4th_gen_tech2.html#Dal_and_Jason

 

A big vote for Jason when buying O2's. Great guy, and though I don't know Dal, I'm sure he would be just as good. Definitely replace your O2's, it's time.

 

Ok, update:

I took the car back to the shop.

The fans were cutting on about 30seconds after the car was started from being cold. At the same time the SES light would come on and the popping would start.

The shop repaired the egr valve? Now the SES light doesnt come on or the fan after 30 seconds, actually I haven't heard the fan cut on since, but it's running about 175 to 180. BUT!

Now the popping doesn't start when it's started cold, it's when you drive it, get it to temperature, then cut it off then restart. Then the popping starts. I have the 02 sensors coming this week. But does this sound familiar to anyone?

Thanks.

 

what if you use your old o2 sensors from a 95 z28 when you change to lt headers?

 

They used the same headers that was on my old engine, I'm sure.