EGR system failed

[pontiacgta2002]

Hello,

99 GMC Yukon 5.7 V8 4X4.

When I test the EGR system with the Solus Pro by Snap-On it lists as failed. When I increase the EGR value by 10% increments it starts to stumble and stalls, as I would assume. Should I replace the EGR with a used one or new if at all? There are no CEL codes showing for the EGR. I have cleaned the deposits from the seat of the EGR. It also travels open and closed without sticking.

I also see when looking at misfires down at the bottom there is a total that fluctuates from 115 - 125. I see random cylinder misfires that never trip the CEL. Things I have done are wires, plugs, rotor cap and button. I have a new distributor on order in case the gear is worn. I also show high ESC count around 220.

Lastly I have a p0430 code showing. I have punched the cats and wonder if that is causing the EGR system to show as failed. I want to rule out any other issue before ordering new cats. I have check all components MAF, MAP, knock sensor, CKP, ECT and EVAP all check out okay according to the Haynes book. I have also checked the injector leak down and all 8 inj. go from 58 PSI to 48 PSI and hold.

 

[SunlitComet]

ignore the egr for now. the misfires don't seem bad. what do you show on history for each cylinder over a one minutes period? are you using all delphi and/or delco parts? High esc counts could be detonation issues. the p 0430 code mean your right cylinder bank converter is chemically wearing out. if you needs replacements magnaflow makes a high flow assembly. cost depends on state of registration. and lastly are you saying you got a 10 psi drop on each injector when doing a balance test? should have 12-13 drop. have you done a injector coil test as well?

 

[pontiacgta2002]

I want to say Delco parts. I have replaced them a few months ago and no longer have the boxes for them. I bought the cap and rotor at NAPA, my sensors at AutoZone. The cats I have gutted and I’m only getting the p0430 and not p0420. That seems weird to me, I figured they would through the code for both post cat banks. Yup 10 PSI drop on each, I have not done the injector coil voltage test as I don’t have the adapter to test it with this scanner. I will need to look through again to make sure I need an adapter.

I will post some saved data later but it’s of a cold system not warmed up to operating temp.

 

[pontiacgta2002]

When clicked on image can be looked at a little easier.

 

[SunlitComet]

420 and 430 are for both cats and the readings look normal for a gutted system. I would put new ones in there. until then your fuel trim will suffer. not to mention among other things it is illegal.