EGR fault

Just recently the CEL started acting...first, would come ON then after some time would shut off....but now it is ON and stable. I was almost sure it had to do with EGR....checked codes and indeed, 55 , large EGR port failure and, accordingly, 56, QUAD driver faulty voltage...obviously because of large EGR port solenoid control. I have not verified the EGR coils yet....will come back later as I'm going out for 2 days....
THIs is a rather new EGR valve...6 or 7 year old.....and in fact, no more than 25000 miles...probably less...

A good thing to try LMP would be to take off the EGR and see if Combustion deposits are making it stick....you probably are aware

Nice thing about OBD2...pcm has deleted EGR...still on my grand prix..for show;-)

"500", since when did OBDII eliminate the EGR? Only ones I know about are on vehicles with variable valve timing....but those are late model cars...

Codes 55 and 56 could be two seperate issues....should clear code and see if one or both come back...

Is this a 3.8? Does it have the EGR with 3 solenoids?

Sorry about the clarification TechII.

The EGR is bypassed on my GTX in an effort to keep the rotors clean on the L67 blower. The PCM has been modified and error codes removed as well as a frequency controlled spoofing device to emulate the EGR.
You might find of interest the electronic devices and performance options available on www.zzperformance.com. They have the worlds fastest front wheel drive 3800. 8.69 seconds for the quarter mile...cheers Kev

Now for the milkshake crap on our vans radiator cap.....(yeah intake gasket time)

[QUOTE=Tech II;6975791
Codes 55 and 56 could be two seperate issues....should clear code and see if one or both come back...Is this a 3.8? Does it have the EGR with 3 solenoids?[/QUOTE]

Yaya..3.8 and 3 sols. A faulty valve will be detected as non operating and bring code 55...if the cause is a shot solenoid, it pops a faulty voltage hence 56....same cause, 2 effects. Totally aware of the intricacies. 55 is the larger of the 3 valves. Will report findings soon...

OK..electrically speaking, the EGR valve is tested OK ..two coils at 22 ohms, and the large one (C) at 11 ohms, just as new. A mechanically stuck valve would bring only code 55, not 55 and 56...hence code 55 fault exist here (inoperative valve) because the electrical signal is not fed to the solenoid..
code 56 is electrical and in this case it does not come from the solenoids...so either I have a blown transistor in the quad driver or a broken wire/contact. More tests to come...
www.avigex.ca/xport/dtc56.jpg
www.avigex.ca/xport/dtc55.jpg

..first run after resistance test initially killed the CEL..then it came back...and now it is 54 and 56. THis looks like the EGR plug contacts are sensitive to manipulation....I had had this problem at the time I had changed the EGR valve...will look again. The wiring harness does not show any sign of heat damage, wear nor cracking...

I had trouble with HID fog lights on my GTX. They have adjustable ballasts.
The very small two prong connector did not make good contact and hence no light output.
I used electrical contact cleaner and packed it with di-electric grease. It is exposed to Chicago cold and salt. Really makes a big difference...Good Luck

I didn't do it....CEL is gone now...well most of the time. Once or twice, it came back for a few seconds....then quit again....
hands off now....just wait and see