spyder24

I have a 1996 Z28 it is all stock except cold air intake and magnaflow exaust. The engine has around 62k on it. It was just put in about 2months ago. I have had the SES light coming on and it says egr flow malfunction. i have read a bit and obviously i can just replace it or check it out. but it only happend after i got this new engine put in. im wondering if maybe he didnt connect somthing up right back there or what. how can i find this out. is there any way it is something else not just the egr valve that could be causing it to be doing this. Also when i got the car back i noticed im not getting any air heat or cold air coming threw my upper vents in the car. it comes threw the bottom and the defrost but not the top vents. The guy at the shop who put the engine in(who turned into an *******) said all you gotta do is switch a vacuum hose around. Im not sure what hose he meant or where to find it. Can anyone help me with these problems or maybe there kinda one problem in one im not sure. Thanks

Injuneer

The HVAC vacuum line comes off the passenger side of the intake manifold. There are 2 vacuum nipples toward the rear of the intake. The top one goes to the HVAC and the bottom one goes to the fuel pressure regulator. From the manifold, the HVAC line goes to a check valve, which can fail. Then the system "tees" with a line going forward to a small vacuum canister in the passenger front fender (near the horns) and the other line from the tee going into the passenger compartment for the HVAC flapper door actuators. The entire system needs to be checked to insure its hooked up, the lines aren't cracked and the check valve isn't damaged.

Shoebox has some info:

Vacuum connection at manifold:

http://shbox.com/1/evap_sol.jpg

Check valve:

http://shbox.com/1/vac_check_valve.jpg

Vacuum canister:

http://shbox.com/1/vacuum_tank.jpg

For the EGR system, the PCM cycles the EGR valve and looks for a change in intake manifold pressure (MAP) to confirm there is flow through the EGR valve. You have to check the corrugated hose that connects from the #8 exhaust manifold runner to the back of the intake to make sure its not cracked or bent, and bolted on tight. Then confirm the EGR valve is operating. With engine idling, put a ground to the gray wire on the EGR vacuum solenoid to verify it is opening the EGR valve (engine will run rough and even stall if EGR is flowing at idle). Make sure the vacuum connection is tight, no cracked hoses, EGR vacuum solenoid works (you would get a different code for EGR vacuum solenoid failure), EGR valve bolts are tight and the gasket is installed.

There was a problem with some EGR valves, and GM may have revised the valves to operate at lower exhaust backpressure. If you still have the EGR valve from the old engine, swap it with the valve from the newer engine.

Again, Shoebox has info:

http://shbox.com/1/egr1.jpg

spyder24

ok thank you ive been trying to check everything out as best as i could. I checked all the vacuum lines and dont see any leaks or anything or cracks. But once again im not real good with stuff like this. As far as the vent problem tho what vacuum line would need switched or is that what i need to do in order to have air threw my upper vents? When the guy put the engine in i mentiond this problem to him and he said just switch one of the vacuum lines. I never took the car back to him because of some issues we had. But i just would lke to know if there is a single line i have to just switch in order to get the proper air flow.