Longtube headers w emissions 95 z28
 

Hi I installed pacesetter lt headers on my 95 z28 and I bought the ones with the Air and egr hookups. I have another thread on here about the right caps to plug off the air holes on the header and I still can’t find the right caps. On another note I got the car together and drove it open headers over to the exhaust shop where they installed my y pipe and they also installed a block off plate for the egr flange on the passenger side header. After I got it home I deleted the egr with the 2 other block off plates I had and the car kinda runs not as good as it used to. Since the header install with an off-road y pipe and a flow master exhaust with no cat I have not noticed any power gains from the stock manifolds. In fact the car felt like it had more power with the stock manifolds on. Also I am hearing a whining noise which sounds like it’s coming from the engine bay. When I capped off the air holes on the header I left the driver and passenger side air pump hoses just laying there... could this be my problem? I read online the air pump only works for a couple minutes on a cold start so I figured it wouldn’t be running as I am driving around with a warm vehicle an hour later. I can’t find out where this noise is coming from and the car seems ever so slightly sluggish. Any input would help. Thanks guys.

Re: Longtube headers w emissions 95 z28
 

Wasn’t Pacesetter able to tell you the size of the AIR connections?

How did you “cap off” the AIR connections on the headers without them?

Are the EGR blockoff plates on the header and for the EGR valve well sealed? The typical aluminum plate for the EGT tube on the #8 primary may not seal well because of the use of only one bolt. Any leaks on that connection, or the AIR connections can screw up the O2 sensor readings. Just driving with open collectors screws the reading up also. The PCM will have to readjust once the Y-pipe was connected.

Re: Longtube headers w emissions 95 z28
 

I just installed the egr plates today and I did not use any kind of sealant on them but I got them really tight. The thing is that when I drove the car from the exhaust shop home the whining and subtle loss of performance and throttle response was still there and hasn’t changed after I got home and installed the egr block off plates after the car had cooled down. It could be the egr tube on the #8 primary but the shop put that on with a gasket and told me they had to shave down the plug to get it to fit inside. Looking back I should’ve bought the race headers and then I wouldn’t have to deal with this stuff after deleting it all. I don’t know quite what is causing this whining noise leak but I do know the car had more power and better throttle response before I installed long tube headers. Pacesetter just got back to me and told me the plug size is 3/4in with 10 pitch.

Re: Longtube headers w emissions 95 z28
 

Sequence of events to me is still unclear. Did you drive the car with the EGR port on #8 primary open, or with the AIR ports open? Did you drive the car with the header collectors open? Did you drive the car with the EGR valve not on the intake manifold? It will not run correctly with any of those.

Re: Longtube headers w emissions 95 z28
 

I drove the car to the shop with open headers, the air ports on the passenger and driver side capped off but the egr port on the #8 primary was open. I only drove it a few miles. The shop hooked up my y pipe and blocked off the #8 primary egr port coming off the header. The egr gas tube was just dangling. I drove it home where I then removed the egr gas tube and installed a block off plate and I also removed the egr and blocked that off as well. So at this point the egr is removed and blocked. The #8 primary egr port off the header is blocked off and the air ports are blocked off with 2 plugs I bought from ace hardware I don’t remember what size they are but they are tapered on the end and more narrow at the bottom so they fit but my driver side keeps coming loose. I have to buy new plugs for that. But I am still hearing a whining noise that was not there before.

Re: Longtube headers w emissions 95 z28
 

Any air entering the exhaust is not good. I got a set of 3 EGR blocking plates. As thick as the one for the #8 primary was, it didn’t look like an absolute seal could be achieved. I cut the “flange” (which is about 1/4” thick) off the header end of the corrugated tube, and used it to sandwich the blocking plate against the header connection, with sensor-safe ultra RTV between the blocking plate and the header connection. The plate for the EGR valve boss was installed with the EGR valve gasket and the RTV. The third plate for the corrugated tube against the intake manifold isn’t really necessary, but I installed it with RTV.

The AIR connections have to be sealed tight. In my case the 22mm-1.5 plugs were a nice tight fit, and I installed them with a copper gasket.

Check your header (head) bolts to insure they are tight. Hopefully you checked the header flanges to insure they are perfectly flat, and used a high quality gasket like the Felpro's. I've also had good luck with the Mr. Gasket copper-seal.