94 Camaro digital EGR valve problem

94 camaro Digital EGR valve 3.4 SFI automatic Service engine light comes on going down the highway when I let off the gas. 3 codes for all three EGR solenoids.
I have pulled the EGR valve off cleaned and tested it with 12 Volts, all three solenoids work. Removed the EGR tube and cleaned it, replaced it with new gaskets, made sure hole to the valve is open. Sprayed the tube with WD40 while the engine was running, no change in the idle (no leaks). With the key on and a wire from the 12 V on the EGR harness and shorting each solenoid to ground works fine. With the engine running and shorting each solenoid there is no difference in the idle of the engine.
Could there be a blockage in the exhaust manifold? Could there be a blockage in the intake manifold or a sensor that detects whether the EGR opened or not? Car runs fine, just tired of seeing the service engine light coming on. I know how too disconnect the service engine light, but thats like taking the battery out of the smoke detector. Any leads on what else to check, would be much appreciated. Thanks
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i have the same problem only i get 2 codes 76, 77 for solenoid 2 and 3,, and code 13 for the o2 sensor,, i replace the EGR and both o2 senosrs,, even put a new cat on,, 10 miles after the codes are cleared it pops up 13,76,77.. have a snap on scanner,, and seems to show o2 sensors working and all three solenoids,, but still comes up with those 3 codes.. anyone know what will fix this?
1994 chevy camaro 3.4 v6 200,000 mile
"Mike" wrote
> 94 camaro > Digital EGR valve > 3.4 SFI > automatic > Service engine light comes on going down the highway when I > let off > the gas. 3 codes for all three EGR solenoids. > > I have pulled the EGR valve off cleaned and tested it with 12 > Volts, > all three solenoids work. Removed the EGR tube and cleaned it, > replaced it with new gaskets, made sure hole to the valve is > open. > Sprayed the tube with WD40 while the engine was running, no > change in > the idle (no leaks). With the key on and a wire from the 12 V > on the > EGR harness and shorting each solenoid to ground works fine. > With the > engine running and shorting each solenoid there is no > difference in > the idle of the engine. > > Could there be a blockage in the exhaust manifold? > Could there be a blockage in the intake manifold or a sensor > that > detects whether the EGR opened or not? > Car runs fine, just tired of seeing the service engine light > coming > on. > I know how too disconnect the service engine light, but thats > like > taking the battery out of the smoke detector. > Any leads on what else to check, would be much appreciated. > Thanks
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djru wrote:

    Pull the EGR back off, and Im sure you will find carbon at the pintle area. The fix is to use a EGR gasket with screen.
    I see this rather often on high mileage engines. after a few miles a chunk of carbon breaks free and clogs the EGR pintle. Charles
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