Fixed one thing now another problem Help!
Drifting
Joined: Mar 2005
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From: GA
Originally Posted by Alvin
I mean anytimey our car commands EGR you get knock counts check it out.
Drifting
Joined: May 2003
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From: Charlotte NC
St. Jude Donor '05
hell who knows.. maybe its a defective unit opening way too much. The problem didn't exsist before he changed it and now it only shows up under halfway decent load with egr commanding on. It only makes since to look at it.
I would put money on a bad valve as you can typically pull the valve off completely on a LT1 and not worry about knocking (they are really tame compared to other GM efi stuff)
To test the solniod you'll have to break out a service manual.
I would put money on a bad valve as you can typically pull the valve off completely on a LT1 and not worry about knocking (they are really tame compared to other GM efi stuff)
To test the solniod you'll have to break out a service manual.
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Le Mans Master
Joined: Dec 2004
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From: Myrtle Beach SC
St. Jude Donor '05-'06
Originally Posted by Alvin
To test the solniod you'll have to break out a service manual.
I got it just need to now wher to ground the test terminal at HELP 
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Le Mans Master
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From: Myrtle Beach SC
St. Jude Donor '05-'06
Originally Posted by slicked25
What does ECM and EGR stand for? My car has some of the symptoms.
EGR is exhaust gas realease valve.
Drifting
Joined: Mar 2005
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From: GA
Originally Posted by Redeasysport
I got it just need to now wher to ground the test terminal at HELP Oh...EGR is "Exhaust Gas Recirculation" valve.
Thread Starter
Le Mans Master
Joined: Dec 2004
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From: Myrtle Beach SC
St. Jude Donor '05-'06
Originally Posted by Morley
Oh...EGR is "Exhaust Gas Recirculation" valve.
I know you mentioned A&B before just was looking for confirmation from someone who has done it already.I get nervous sticking wires into the ALDL if you know what I mean.
So it looks like the EGR is where I am going to spend some quality time with again toinight after work.I do believe the valve is at least capable of working.If anything at this point it may be the solenoid or a plugged passage but I doubt the passage as I cleaned it out with the intake off stuck my fingers in it to check.Somehow I think the 20mmHg at the manifold is not making it to the EGR either solenoid or leak.
Now my question is shouldn't I get a code 32 if it is not?Could it be co incedence that the knocks appear when the EGR is commanded to open?Stay tuned for next exciting chapter of "As the Engine Knocks"....
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Thread Starter
Le Mans Master
Joined: Dec 2004
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From: Myrtle Beach SC
St. Jude Donor '05-'06
I did that it ran the some what the same.Still does not tell me if the solenoid is coming on or not which will tell me what to replace EGR or solenoid.I suppose I could get some hose and tape the mightyvac to the windshield but it would be kinda hard to see.Still looking to test it according to the FSM it should be easy enough if I ground the right thing.
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Le Mans Master
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From: Myrtle Beach SC
St. Jude Donor '05-'06
No I do not have a scan will try one tonight.At this point I am guessing indeed the EGR is not opening.The FSM says this will cause knock.I have tested the EGR off the car and it functions.I suspect the solenoid switch.A massive intake leak that would effect the EGR supply is a possibility and I will check that tonight too I only tested at the manifold.I doubt that is the case though I would think a leak that big would cause other problems.
There is a possibility the the EGR itself is malfunctioning(remote) but to elminate that I have to verify that the solenoid works.
There is a possibility the the EGR itself is malfunctioning(remote) but to elminate that I have to verify that the solenoid works.
Drifting
Joined: May 2003
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From: Charlotte NC
St. Jude Donor '05
I think its openig too much. If it was leaking it would be leaking all the time. We know its opening because you've tested it.
I've said before that you can completely remove the EGR off a 93 and not have any spark retard, its a problem moreso with the iron headed TPI and TBI cars and trucks. the LT1's are too forgiving for that to be a issue especially at 12+ degrees of retard.
I've said before that you can completely remove the EGR off a 93 and not have any spark retard, its a problem moreso with the iron headed TPI and TBI cars and trucks. the LT1's are too forgiving for that to be a issue especially at 12+ degrees of retard.
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Le Mans Master
Joined: Dec 2004
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From: Myrtle Beach SC
St. Jude Donor '05-'06
I know it is capable of opening.I can't verify it has opened though.So you are saying that with the EGR disconnected it should run OK.This is one time I hope you are wrong.The FSM lists the symptoms of too much or too little EGR and knock is one for too little although too much can cause hesitation.If it is supposed to run OK with it disconnected the I have a real knock(I hope not).I think the exhaust was contributing to some false knocks as the buzz was pretty loud when the knock would occur now it is gone with the crossframe off.I will get a scan with it disconnected and plugged tonight.
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Le Mans Master
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From: Myrtle Beach SC
St. Jude Donor '05-'06
Originally Posted by Alvin
the second log you posted had just as much "knock" as the first
post the log with everything capped off (so it can't open if it wanted to) and we will go from there.
post the log with everything capped off (so it can't open if it wanted to) and we will go from there.
Thread Starter
Le Mans Master
Joined: Dec 2004
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From: Myrtle Beach SC
St. Jude Donor '05-'06
OK Alvin it appears you are right again 
Did the block off and it runs perfectly I have not looked at the scan myself yet wanted to get it up here for you.So it look like the EGR is bad and not the solenoid because it was obviously turning on and causing knocks.Thanks to all especially Alvin and Morely for your help.
Don't you hate it when new parts go bad and I have had more than my share on this car.Makes me not want to work on it.But I can imagine what a nightmare the dealer would have been.
Another successful Corvette Forum diagnosis Isn't this a great place to get help with your car?
Here is the file it is short battery went down fast again
Did the block off and it runs perfectly I have not looked at the scan myself yet wanted to get it up here for you.So it look like the EGR is bad and not the solenoid because it was obviously turning on and causing knocks.Thanks to all especially Alvin and Morely for your help.
Don't you hate it when new parts go bad and I have had more than my share on this car.Makes me not want to work on it.But I can imagine what a nightmare the dealer would have been.
Another successful Corvette Forum diagnosis Isn't this a great place to get help with your car?
Here is the file it is short battery went down fast again
Drifting
Joined: May 2003
Posts: 1,730
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From: Charlotte NC
St. Jude Donor '05
I should add this to the post I made in scan & tune. Problems can be found easily with datalogs!
Look at the datalog now, do you see EGR being commanded on but the knock sensor is completely quiet. I think you nailed the problem now..
Good job. I'll bet it feels tons better without the 12-14 degrees of timing being pulled.
Look at the datalog now, do you see EGR being commanded on but the knock sensor is completely quiet. I think you nailed the problem now..
Good job. I'll bet it feels tons better without the 12-14 degrees of timing being pulled.
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Le Mans Master
Joined: Dec 2004
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From: Myrtle Beach SC
St. Jude Donor '05-'06
Yep the only knocks were on start up.She pulls real nice I will sleep much better tonight.Yes I would have never figured it out without tossing money at it to replace "New" parts.Makes the money I will have to pony up to TT in 9 more scans a little easier to swallow.
Drifting
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From: GA
Originally Posted by Redeasysport
Don't you hate it when new parts go bad and I have had more than my share on this car.
The reason I ask is that the parts store EGR valves are (according to a few sources) just a generic EGR that could possibly fit a wide range of vehicles but are not metered correctly for a specific application. I have also seen some parts store EGR's that come with several orafices to change out, depending on your vehicle....Not the way to go. Most say to get your EGR valves directly from the dealer to ensure you are getting the right item for the vehicle.
