Fixed one thing now another problem Help!
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Your new one ought to be easy enough to check. If it starts out low enough, ends up high enough and sweeps smoothly and cleanly in between, it's good. I just wish I had the min. and max. voltages to give you. I think the smooth transition is your main concern with this problem, anyway.
RACE ON!!!
RACE ON!!!
Thread Starter
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
Thats the problem CFI there is a spot that I can push the pedal to that the bucking occurs at.It is hard to tell but it seems to be around the same postion.It occurs @65mph holding speed and give it a little more pedal it will break up untill I get close to WOT.It will also happen when starting out but it usually shifts before it happens much but I can feel it.I have not been able to link it to any specific rpm though.
Race Director
Joined: Aug 2003
Posts: 13,421
Likes: 8
From: Lake Mary Florida
The plastic vacuum tube that routes from the EGR, manifold, and loops around to the ASR. If yours is marginal or brittle it may be leaking. P/N 10105325, about $7.-8. plus shipping. You can find the last few at Vintage Parts 1-877-846-8243.
Don't drive yourself too nuts, some times these things have a way of masking themselves. I chased a similar problem during the summer with EGR & assy, O2, Tach filter, plugs, wires, new coil and ignition module, new connector and finally a reman ECM. I had a lot of your symptoms but I was getting serial data codes plus a few others as well.
I think Bogus refers to these as cascading sets of problems.
You mentioned replacing the TPS have you taken it in to the stealer to have the run the learn throttle position program on the Tech 1? I started to replace mine when I spotted that note, and instead took it in to have them swap out the TPS's and run the program.
Don't rule out the ECM yet, it's not that expensive and it can cause these types of problems. Do a search on ECM and you'll find some interesting reading here.
Don't drive yourself too nuts, some times these things have a way of masking themselves. I chased a similar problem during the summer with EGR & assy, O2, Tach filter, plugs, wires, new coil and ignition module, new connector and finally a reman ECM. I had a lot of your symptoms but I was getting serial data codes plus a few others as well.
I think Bogus refers to these as cascading sets of problems.
You mentioned replacing the TPS have you taken it in to the stealer to have the run the learn throttle position program on the Tech 1? I started to replace mine when I spotted that note, and instead took it in to have them swap out the TPS's and run the program.
Don't rule out the ECM yet, it's not that expensive and it can cause these types of problems. Do a search on ECM and you'll find some interesting reading here.
Thread Starter
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
No I did not do the relearn.My take is that is for ABS/ASR functions to retard the fuel and mine work as they are supposed to.I did replace the fittings on the vacuum lines they look to be in good shape.I did verify the EGR as being bad it would hold no vacuum for more than 1 sec it would barely move.I tested it with my Mityvac.The new one held it for 20sec.I unfortunately will drive myself nuts fixing this.I don't mind a known problem as much as an unknown one.I cannot trust the car right now so it stays close to home and it makes it useless to me.I will keep the ECM in mind after I have exhausted everthing else.I remember your thread I was in it too.That was a nightmare and you showed a lot of tenacity.
Last edited by Redeasysport; Jan 2, 2006 at 08:47 PM.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by Redeasysport
Thats the problem CFI there is a spot that I can push the pedal to that the bucking occurs at.
Originally Posted by CFI-EFI
Your new one ought to be easy enough to check. If it starts out low enough, ends up high enough and sweeps smoothly and cleanly in between, it's good. I just wish I had the min. and max. voltages to give you. I think the smooth transition is your main concern with this problem, anyway.
RACE ON!!!
Race Director
Joined: Aug 2003
Posts: 13,421
Likes: 8
From: Lake Mary Florida
Yep sadly I remember too well as well. I know exactly the feeling your having right now, that loss of trust factor. Once they've left you stranded you may forgive it once it's repaired but you never forget!
Drifting
Joined: Mar 2005
Posts: 1,923
Likes: 0
From: GA
Originally Posted by CFI-EFI
Careful, you're talking to the sensor/gauge expert.He has looked at his 8 year older Camaro and determined that ALL GM cars have to be the same.
I'd love to confirm your suspicions, Redeasysport, but my expertise on that subject ends with 1989. For what it is worth, I believe you are correct.
RACE ON!!!
I'd love to confirm your suspicions, Redeasysport, but my expertise on that subject ends with 1989. For what it is worth, I believe you are correct.
RACE ON!!!
I, for one, am sick of you childish, arrogance. you have something to prove? Go on over to thirdgen.org and hang out with the rest of the little teenagers, you'll fit right in.
Last edited by Morley; Jan 2, 2006 at 10:59 PM.
Thread Starter
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
First no fighting guys I appreciate everyones help.And it looks like I am going to need it.
Second I am totally bummed now.I did the datamaster scan only got about 5 min cause now I need a new battery for the laptop but it was enough.5000 knocks.5000 KNOCKS
.I am guessing a bad EGR will not cause that many and although I can't hear them(Exhaust is a little loud) they must be the source.Now what?
I have had a little time to digest the above and guess I am going to have to check out the EGR so when it says in the manual to ground the test terminal to activate the solenoid it means terminals A&B on the ALDL?Gonna have to get the mightyvac out turn it on and see if the EGR is moving or not.One thing in the scan when it turned the egr on it was alway asking for 100% is that normal?
Here is the file
Second I am totally bummed now.I did the datamaster scan only got about 5 min cause now I need a new battery for the laptop but it was enough.5000 knocks.5000 KNOCKS
.I am guessing a bad EGR will not cause that many and although I can't hear them(Exhaust is a little loud) they must be the source.Now what?I have had a little time to digest the above and guess I am going to have to check out the EGR so when it says in the manual to ground the test terminal to activate the solenoid it means terminals A&B on the ALDL?Gonna have to get the mightyvac out turn it on and see if the EGR is moving or not.One thing in the scan when it turned the egr on it was alway asking for 100% is that normal?
Here is the file
Last edited by Redeasysport; Jan 3, 2006 at 12:14 AM.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Drifting
Joined: Mar 2005
Posts: 1,923
Likes: 0
From: GA
5000 knock counts... But the max knock retard I saw was 1.8*. From what I saw of the EGR operation in that file it seems like it is working, EGR is an on or off operation, so 100% is on and 0.0 is off. What may be happening is the EGR is being requested but the ECM isn't seeing the proper feedback to say it got what was requested. In a MAP based system it is looking for a slight drop in MAP value, indicating that the vacuum is actuating the EGR valve.
Those may not be actual knock counts, the sensor may be picking some noise from something else. Seems like every time you go more than 10% TPS the knock count goes up.
Those may not be actual knock counts, the sensor may be picking some noise from something else. Seems like every time you go more than 10% TPS the knock count goes up.
Last edited by Morley; Jan 3, 2006 at 12:58 AM.
Thread Starter
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
So is the retarding enough to cause the bucking I feel?Wish I could have gotten more on the scan mabey I will try again after I recharge the battery.I am at a loss could the egr being stuck/bad cause this?
And how do I ground the "test terminal" to activate the solenoid?
And how do I ground the "test terminal" to activate the solenoid?
Last edited by Redeasysport; Jan 3, 2006 at 01:24 AM.
Drifting
Joined: May 2003
Posts: 1,730
Likes: 1
From: Charlotte NC
St. Jude Donor '05
Datamaster is off on the knock retard by a factor of 10. So take that 1.3 that I'm seeing and you actually have 13 which is consistant with the reported timing is saying and what the stock timing table in that load area will call for. You can test this also if you have some tuning ability by filling in all your max knock retard tables to something like 3 degrees.. you'll then only see .3 as a retard. Datamaster only has this problme with the DA cars.
I'm going to go out on a limb and say that all of these problems are probally 90% EGR related. TPS seems to be working A-OK looking at the datalog. Your running into problems anytime EGR is commanded and you are into some load (70kpa or higher)
I've seen this alot before in the TBI trucks.. pretty unusual to see a knock related EGR problem in a LT1.
The 92-93's are usually pretty tame about knocking and knock counts..
My suggestion for diagnostic purposes would be to take a screw driver and push the hard steel diaphram of the EGR valve to make sure it feels like its going to spring back ok. If that seems ok than remove the vaccum line from the EGR valve, cap the soleniod and take it for a ride. This will prevent and check engine lights and assuming you have decent gas in the car you shouldn't pick up any/much knock.
I'm going to go out on a limb and say that all of these problems are probally 90% EGR related. TPS seems to be working A-OK looking at the datalog. Your running into problems anytime EGR is commanded and you are into some load (70kpa or higher)
I've seen this alot before in the TBI trucks.. pretty unusual to see a knock related EGR problem in a LT1.
The 92-93's are usually pretty tame about knocking and knock counts..
My suggestion for diagnostic purposes would be to take a screw driver and push the hard steel diaphram of the EGR valve to make sure it feels like its going to spring back ok. If that seems ok than remove the vaccum line from the EGR valve, cap the soleniod and take it for a ride. This will prevent and check engine lights and assuming you have decent gas in the car you shouldn't pick up any/much knock.
Last edited by Alvin; Jan 3, 2006 at 01:51 AM.
Drifting
Joined: Mar 2005
Posts: 1,923
Likes: 0
From: GA
Originally Posted by Alvin
Datamaster is off on the knock retard by a factor of 10. So take that 1.3 that I'm seeing and you actually have 13 which is consistant with the reported timing is saying and what the stock timing table in that load area will call for.
I've never heard of EGR causing knock, I've heard of getting knock (pinging) if it wouldn't open or the passages were blocked.
I agree, that if he is pulling 13-18* of timing, that is the cause of the hesitation/bucking. Now to determine if it is real kock or false.
Thread Starter
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
Thanks Alvin.I tried the push the diaphram thing and the rpms went UP.The FSM said they should go down.What does that mean? I am pulling 20mmHg at idle I pulled and re tested the EGR it retracts at 5mmHg. I tried the disconnect the EGR and plug the vacuum test and it was better but still hesitated.I guess I will have to scan it with it disconnected to see how the knocks are I am running 94 octane.Back at it tomorrow........
Drifting
Joined: May 2003
Posts: 1,730
Likes: 1
From: Charlotte NC
St. Jude Donor '05
Originally Posted by Morley
That makes sense then. On his data log there was one instance of 1.8* retard but the total timing was only 8*...26 makes more sense.
I've never heard of EGR causing knock, I've heard of getting knock (pinging) if it wouldn't open or the passages were blocked.
I agree, that if he is pulling 13-18* of timing, that is the cause of the hesitation/bucking. Now to determine if it is real kock or false.
I've never heard of EGR causing knock, I've heard of getting knock (pinging) if it wouldn't open or the passages were blocked.
I agree, that if he is pulling 13-18* of timing, that is the cause of the hesitation/bucking. Now to determine if it is real kock or false.
I'm thinking that the car is running so poorly when the EGR valve finally opens that hes getting knock OR.. the thing isn't really opening and hitting some knock retard.
some times on cars with bad misfires they will throw the knock sensor all aroudn just because the engine is shaking and runnning so poorly.
Thread Starter
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
Ok lets talk.
I obviously have a knock problem that I can't hear.It ran great for a while then this dropped out of the sky.If it isn't the rods what could it be?Could exhaust vibrations cause this?I do have a buzz from one side of the exhaust that I have been chasing too.
If not exhaust what else could cause knocks.It does not appear to me to be misfiring at idle.It seems to occur under load,anything significant about that?Could the tranny cause it?
Obviously something changed after the Intake /EGR replacement.Any possibilities that this is the source?
I hate to even think it but can a bad opti /cap play into this although the Dynaspark is only 6mo old stranger things have happened.
And what "test terminal" must be grounded to activate the solenoid?It is the only untested part and I would like to eliminate it as a cause.
I obviously have a knock problem that I can't hear.It ran great for a while then this dropped out of the sky.If it isn't the rods what could it be?Could exhaust vibrations cause this?I do have a buzz from one side of the exhaust that I have been chasing too.
If not exhaust what else could cause knocks.It does not appear to me to be misfiring at idle.It seems to occur under load,anything significant about that?Could the tranny cause it?
Obviously something changed after the Intake /EGR replacement.Any possibilities that this is the source?
I hate to even think it but can a bad opti /cap play into this although the Dynaspark is only 6mo old stranger things have happened.
And what "test terminal" must be grounded to activate the solenoid?It is the only untested part and I would like to eliminate it as a cause.
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
A couple things-first I own an 87-so I'm not really sure about your year-in your last post I suggested the EGR switch-which Morley let me know your year doesn't have. I think I also suggested you check your wires to the knock sensor-did you do this? I know others here found that the wires to the knock sensor was causing them problems. And the one thing I can tell you for sure is this past summer I definetly got some bad fuel (twice) my daughter once! But the second time it took 2
bottles of heat through the system to clear MY problem.Good Luck.
bottles of heat through the system to clear MY problem.Good Luck.
Thread Starter
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
I removed my RD cross frame brace as it was the source of my muffler vibration.Big difference car is 85% better but still getting some knocks and hesitation under load and light throttle.I know I am missing the cat hanger bolts on the pass side and wonder if that is part of the trouble.I have a new scan after I took the crossframe off.
I also put 10 gal of 93 from another station and can't tell for sure but it seemed that cut some knock out.I have not done a scan with the new gas yet.Still a touch of hesitation under load and light throttle.Overall the car now runs almost as good as it did right after the intake job and that is a good thing.
My take is when the egr opens it changes the engine enough to vibrate the exhaust(I got a lot of buzz in the interior when the problem occured)I have no buzz that I can hear although that does not mean it is not there at the hanger bracket.
Alvin please look at the new scan and tell me what you think.Data master what a concept.For those who don't have it and work on your car you can see from this thread what the benefits are.
I also put 10 gal of 93 from another station and can't tell for sure but it seemed that cut some knock out.I have not done a scan with the new gas yet.Still a touch of hesitation under load and light throttle.Overall the car now runs almost as good as it did right after the intake job and that is a good thing.
My take is when the egr opens it changes the engine enough to vibrate the exhaust(I got a lot of buzz in the interior when the problem occured)I have no buzz that I can hear although that does not mean it is not there at the hanger bracket.
Alvin please look at the new scan and tell me what you think.Data master what a concept.For those who don't have it and work on your car you can see from this thread what the benefits are.
Drifting
Joined: May 2003
Posts: 1,730
Likes: 1
From: Charlotte NC
St. Jude Donor '05
Graph EGR DC with knock retard.
You still have a problem. It looks like something is wrong with that EGR valve you installed causing the engine to run rough enough to trip knock counts.
If you graph knock retard with DC you'll see that anytime you have any load on the car (say 60+kpa) and EGR is 100% the car stubles in spark knock all over the place.
You still have a problem. It looks like something is wrong with that EGR valve you installed causing the engine to run rough enough to trip knock counts.
If you graph knock retard with DC you'll see that anytime you have any load on the car (say 60+kpa) and EGR is 100% the car stubles in spark knock all over the place.
Drifting
Joined: May 2003
Posts: 1,730
Likes: 1
From: Charlotte NC
St. Jude Donor '05
also, little datamaster hint..
After you graph say RPM, EGR DC, and Knock retard at the bottom right click and draw a box around a rough area.. it will let you zoom in.
I mean anytimey our car commands EGR you get knock counts check it out.
After you graph say RPM, EGR DC, and Knock retard at the bottom right click and draw a box around a rough area.. it will let you zoom in.
I mean anytimey our car commands EGR you get knock counts check it out.
Thread Starter
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
Thanks Alvin now the answer I have been asking for how do I ground the "test terminal" to activate the solenoid?I don't think it is the source but want to verify it anyway.It does say in the FSM if the EGR is not opening it can cause knocks so mabey it is the problem though.But can't you block off the EGR and run like that or is that a no no on LT1's?
So now what take the EGR back?It sure seems to operate correctly off the car.
So now what take the EGR back?It sure seems to operate correctly off the car.