AtlantaGAJoe

So, I've been working through an EGR problem and thought it was the valve, as it would not hold vacuum when the engine was running. I replaced the valve and can manually operate it, but the PCM is still throwing a code #27, EGR electrical fault.

Does this sould like it could be the solenoid? I tested it by following some steps I found on Shoebox's site. I also have headers. Could this have something to do with it?

Cooud an exhaust leak at the header collectors cause this problem? I'm taking the car to the muffler shop on Friday to get the collector gaskets replaced.

I'm stumped at this point, but would really like to correct this problem.

Thanks in advance.

Joe

Guest47904

A 27 means the PCM has detected the wrong voltage on the grey wire going to the EGR solenoid. It is on the red PCM conector, pin 9.

The solenoid is turned on and off by the PCM providing the solenoid with a ground when it turns it on and takes away the ground when it turns it off. This line from PCM to the solenoid is monitored when it's not at ground potential for the voltage level going to it. The solenoid has 12 volts to it at all times from the #6 10amp fuse which is labeled fans/actr. In other words the power is direct and the ground is switched on or off.

You need to check first the grey wire from the PCM to the solenoid to be sure it is not cut or has any loose connections. This is most easily done by checking the presence of 12 volts at pin 9 while wiggling the entire length of the wire and the connectors.

The 12 volt supply to the EGR solenoid is also shared by the evap solenoid, the fan relays, both O2's and in the case of a manual tranny (you didn't mention) the reverse lockout solenoid and the skip shift solenoid. Therefore any one of those devices or the wiring going to them could have a problem where they are momentarily pulling the supply line toward ground potential and causing your problem. Start with the circuit in question and then move on to the other components shared by the same fuse. Wouldn't hurt to pull the fuse and reseat it also.

While it's at the muffler shop, have them look at the wires going to the O2's. I don't know why but when many put on headers, they don't care for the wires going to the O2's like they should and they burn through and touch ground. Sometimes intermittently. You would think it would blow the fuse but several have not.

AtlantaGAJoe

Wow! Thanks for the good info, Speedy. This gives me a few things to check out.

Something else dawned on me when I reviewed your reply and realized the fan wiring tied into this as well. Some time ago I did the fan switch mod. I never could get the LED's to work, even without the resistors. I wonder if that mod has something to do with it. I think I'll snip those two wires going to the PCM harness and see what happens.

Other than that, I'll be checking the other things you mentioned and will hopefully get this problem beat.

Thanks,
Joe

94Z28LS1toLT1

Joe im getting code 27 n i replaced egr valve n the egr solenoid,but did u ever fix ur code,but i got 2 wires from the junk yard that go to that egr solenoid i kno mine is bad bc its loose,but if u cn let me kno thank u

shoebox

Looks like Joe may have sold his car and has been gone from the board for about 5 years (by his last post). You may not get a response from him. That's the risk of digging up a real old thread.

94Z28LS1toLT1

May i get an answer from you rob code 27 is all i have i

shoebox

You said you had bad wires to the EGR solenoid. I'd sure start there (I thought you were already doing that). The computer is complaining that the circuit does not look electrically proper. That includes the wiring and the solenoid.

94Z28LS1toLT1

Thank u rob n a shout out to you too Fred my engine is perfect no code 27 n no code 48 n the engine isnt reving on its on,my maf was bad for the 48 code n i swapped the wire on the code 27 n now gone