EGR Codes With Brand New EGR Vavle
#1
03-12-2012, 02:28 PM
Join Date: May 2010
Location: Missouri
Posts: 3,402
EGR Codes With Brand New EGR Vavle
Like the title says, I am throwing code #76 and #77 (EGR #2 and #3 Failure) and my EGR Valve is brand new. Any ideas what would cause this? Also my car sputters unless I'm at WOT... Also have backfiring in the intake every once in awhile
#5
03-12-2012, 06:35 PM
egr issues
It's been a few years but I think that this sled has the famous linear egr valve.
As most will tell you, pull the valve to see if it has a chunk of carbon holding any of its ports open.
If nothing visible, install a solid hand made gasket that blocks off all holes on this linear egr valve.
You'll still get the code but it will eliminate any faulty wiring or malfunctioning PCM driven symptoms in relation to the egr system.
The valves and intakes clog easily on the 6-bangers.
Check the obvious then send me your scats again and I'll try to walk you through the electrical diagnosis end.
Hey, if you have an outdated Tech-II laying around or a buddy with one you can work miracles.
All I have now is my trusty Fluke 87 and it has been nearly 20 years.
I'm new to the post so I'm sure that anything I know has already been done or said before but I'll try to help where I can.
As most will tell you, pull the valve to see if it has a chunk of carbon holding any of its ports open.
If nothing visible, install a solid hand made gasket that blocks off all holes on this linear egr valve.
You'll still get the code but it will eliminate any faulty wiring or malfunctioning PCM driven symptoms in relation to the egr system.
The valves and intakes clog easily on the 6-bangers.
Check the obvious then send me your scats again and I'll try to walk you through the electrical diagnosis end.
Hey, if you have an outdated Tech-II laying around or a buddy with one you can work miracles.
All I have now is my trusty Fluke 87 and it has been nearly 20 years.
I'm new to the post so I'm sure that anything I know has already been done or said before but I'll try to help where I can.
Last edited by oldwrench; 03-12-2012 at 07:45 PM.
#7
03-13-2012, 12:18 PM
Since both egr valves are having trouble, I would assume the problem is farther up the line. Based on this article, I would assume it is either a vacuum leak or no signal to the EGRs. EGR Valve Failure Symptoms | eHow.com
Have you checked your fuses?
Have you checked your fuses?
#8
03-13-2012, 02:16 PM
Join Date: May 2010
Location: Missouri
Posts: 3,402
My car has 3 EGR solenoids. Not 2... And I thought of a vacuum leak but I can't seem to find one. I can hear a slight whistling sound when I shut down the engine tho.
#9
03-13-2012, 07:13 PM
Do you have any EVAP codes?
If your cooling fans and evap system are malfuntioning make sure that you are getting battery voltage (key on engine off) to pin D of the EGR connector. This EGR valve has 12 volts common to pin D with simple grounds applied by the PCM in stages to the 3 solenoids in an effort to achieve exhaust gas recirculation without the operator feeling in the pedal while reducing emissions.
If no problems.
The O2 sensors pass judgement on EGR performance, I'm assuming that there are no O2 codes and the vehicle can achieve closed loop operation? Get a cheap scan tool. Most offer enhanced diagnostics for GM vehicles.
Inspect the EGR connector and pins really closely for lost pin retention. Bend the tangs for better contact if needed then do the run test again.
Being that I can't rule out the stuff that I would have eliminated during a visual inspection and test drive, I will assume that you've had a mechanic take a peak at some point in time?
Free advice if it were mine. Follow these recommendations if you are a good tech or find one that you trust. These steps will identify EGR issues, head-intake clogs, PCM or related wiring as the culprit and I would appreciate a high-five if you fix your ride. I wrenched these when they were new and this is what I had to find on my own then tell the O.E.M. so they could put it in their T.S.B.s
That being said:
DISCONNECT ALL CONNECTORS TO YOUR PCM
If you decide to cut the 3 negative signal wires at the EGR harness in half to check for a short to ground on the PCM side (on any of the three wires with a good DVOM) I applaud you, as this would be the next step a capable mechanic would do if no scan tool available and all else is 100%. At idle or road conditions there should be no ground signal from the PCM to any of the 3 linear pack EGR connectors (12VDC will be on the 1 uncut wire).
If there is any ground signal on any of the 3 PCM circuits then you have a shorted harness problem.
If no problems, Inspect your new valve for chunks in the pintles.
NOW, PUT ON YOUR SAFETY GOGGLES IF YOU CHOOSE TO READ FURTHER!
There should be no major visible coking in the ports with the EGR valve removed and you should feel pressure or vacuum on all 4 holes (can't remember which but all should have one or the other or its blocked deeper in the manifold or head) when running the motor while a buddy feathers the gas to keep it running (1500-2000 rpm) with the EGR valve off of the car.
DO NOT PUT YOUR FACE IN FRONT OF THE OPEN EGR PORTS WHILE CRANKING THEN RUNNING YOUR ENGINE WITHOUT THE VALVE INSTALLED!
WEAR SAFETY GLASSES AND EXPECT BLACK CHUNKS OF CARBON TO FLY FROM THE OPEN PORTS WHICH CAN BLIND YOU!
You may get lucky and blow out the crud so it doesn't trash your new EGR valve again. If the codes return, eventually you'll have to manually clean the passages.
Not a biggie, just gotta pull the intake then chisel the crud where you see it then use a strong vacuum to suck it from the passages. Now you have to ask yourself the question; I'm committed at this point do I need to follow through by pulling the heads?
Ideally, pull the heads and intake if there are any minor blockage issues then clean them up or have your local reputable machine shop work the magic.
Nothing but gaskets and a little time spent on your baby.
If your cooling fans and evap system are malfuntioning make sure that you are getting battery voltage (key on engine off) to pin D of the EGR connector. This EGR valve has 12 volts common to pin D with simple grounds applied by the PCM in stages to the 3 solenoids in an effort to achieve exhaust gas recirculation without the operator feeling in the pedal while reducing emissions.
If no problems.
The O2 sensors pass judgement on EGR performance, I'm assuming that there are no O2 codes and the vehicle can achieve closed loop operation? Get a cheap scan tool. Most offer enhanced diagnostics for GM vehicles.
Inspect the EGR connector and pins really closely for lost pin retention. Bend the tangs for better contact if needed then do the run test again.
Being that I can't rule out the stuff that I would have eliminated during a visual inspection and test drive, I will assume that you've had a mechanic take a peak at some point in time?
Free advice if it were mine. Follow these recommendations if you are a good tech or find one that you trust. These steps will identify EGR issues, head-intake clogs, PCM or related wiring as the culprit and I would appreciate a high-five if you fix your ride. I wrenched these when they were new and this is what I had to find on my own then tell the O.E.M. so they could put it in their T.S.B.s
That being said:
DISCONNECT ALL CONNECTORS TO YOUR PCM
If you decide to cut the 3 negative signal wires at the EGR harness in half to check for a short to ground on the PCM side (on any of the three wires with a good DVOM) I applaud you, as this would be the next step a capable mechanic would do if no scan tool available and all else is 100%. At idle or road conditions there should be no ground signal from the PCM to any of the 3 linear pack EGR connectors (12VDC will be on the 1 uncut wire).
If there is any ground signal on any of the 3 PCM circuits then you have a shorted harness problem.
If no problems, Inspect your new valve for chunks in the pintles.
NOW, PUT ON YOUR SAFETY GOGGLES IF YOU CHOOSE TO READ FURTHER!
There should be no major visible coking in the ports with the EGR valve removed and you should feel pressure or vacuum on all 4 holes (can't remember which but all should have one or the other or its blocked deeper in the manifold or head) when running the motor while a buddy feathers the gas to keep it running (1500-2000 rpm) with the EGR valve off of the car.
DO NOT PUT YOUR FACE IN FRONT OF THE OPEN EGR PORTS WHILE CRANKING THEN RUNNING YOUR ENGINE WITHOUT THE VALVE INSTALLED!
WEAR SAFETY GLASSES AND EXPECT BLACK CHUNKS OF CARBON TO FLY FROM THE OPEN PORTS WHICH CAN BLIND YOU!
You may get lucky and blow out the crud so it doesn't trash your new EGR valve again. If the codes return, eventually you'll have to manually clean the passages.
Not a biggie, just gotta pull the intake then chisel the crud where you see it then use a strong vacuum to suck it from the passages. Now you have to ask yourself the question; I'm committed at this point do I need to follow through by pulling the heads?
Ideally, pull the heads and intake if there are any minor blockage issues then clean them up or have your local reputable machine shop work the magic.
Nothing but gaskets and a little time spent on your baby.