lt1 Heavy bog-knock retard.
05-16-2010, 04:22 PM
#1
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lt1 Heavy bog-knock retard.
Usually figure this stuff out on my own but this one has me stumped. Iwanted to get some insight here before I take it to the shop and admit defeat.
I will describe the symptoms as best I can. This car has given me 6 years of trouble free service. Always well maintained. Daily driver, I put maybe 6000 miles a year on it. Started having problems about a month ago. Occasionally I would get a "rough" start cold. It idles fine after start. This rough start condition has no consistency either. It may happen the next day or not for a week.
After start and warmup "normal" driving shows no symptoms until I gradually increase throttle. For example; 4th gear 50mph, slowly increase throttle to overtake or pass and the engine will fall flat on it's face. Audible and heavy detonation. I can shift to a lower gear and this will help somewhat but It is still not pulling like it should.
Best I can describe it is the car is either "on or off" I can drive like gramps or a bat outta hell.........I have no in between. Hope that makes sense.
I have checked MAF, MAP,IAT,TPS, KNOCK SENSOR and all of their related circuits, everything so far checks out with factory specs. I have ruled out bad gas. several tanks since this started.
No SES light since this trouble began.
Any insight here would be appreciated.
Thanks.
I will describe the symptoms as best I can. This car has given me 6 years of trouble free service. Always well maintained. Daily driver, I put maybe 6000 miles a year on it. Started having problems about a month ago. Occasionally I would get a "rough" start cold. It idles fine after start. This rough start condition has no consistency either. It may happen the next day or not for a week.
After start and warmup "normal" driving shows no symptoms until I gradually increase throttle. For example; 4th gear 50mph, slowly increase throttle to overtake or pass and the engine will fall flat on it's face. Audible and heavy detonation. I can shift to a lower gear and this will help somewhat but It is still not pulling like it should.
Best I can describe it is the car is either "on or off" I can drive like gramps or a bat outta hell.........I have no in between. Hope that makes sense.
I have checked MAF, MAP,IAT,TPS, KNOCK SENSOR and all of their related circuits, everything so far checks out with factory specs. I have ruled out bad gas. several tanks since this started.
No SES light since this trouble began.
Any insight here would be appreciated.
Thanks.
Last edited by Antigone; 05-17-2010 at 06:54 AM. Reason: added text
05-17-2010, 09:22 AM
#2
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Posts: 910
You say you have knock retard, so I assume you have a scanner. There are a couple of DTC's (OPTI and ICM) that do not light the SES, just want to make sure you don't have any of them. Problem with these OBD1's is as long as the input to ICM is good that's the end of any diagnostic tracking. Any failures in the coil, ICM output to coil, OPTI (HV) rotor, coil HV wire, plug wires, plugs is not detected. Burnt plug wires with headers is very common and shows at come/go type failures under higher load situations. Would be nice to see if your knock count is incrementing when spark is retarding or if PCM is pulling spark for another reason. I would get ICM and coil tested as they are very big culprits on these F-body's for intermittent engine running problems. Also look for sparks in the dark around HV lines coil, etc..
05-18-2010, 07:57 AM
#3
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Thanks for the input.
I need to add some things that I left out in my original post. No I do not have a scanner. I can only go by what I hear and feel as far as knock retard. Now that I think about it as heavy as the knock,detonation is, clearly audible, and how badly it falls on it's face I am only assuming that it has reached the limits of knock retard.
Also I should clarify the "rough start" condition I mentioned. Usually it starts with a quarter turn of the starter. More times than not it will start normally. When I experience a bad start it is almost like the starter is in a bind. It will turn over, stop for a second,and finally start. (Timing problem?),(misfire at startup?) I am starting to suspect plug wires as this only happens under load and not at normal cruise. When it does start it feels like something is hitting the floorboard from underneath. I have checked underneath for anything loose or touching the frame and found nothing. Mounts appear to be in good condition.
The car had 113,000 miles on it when I bought it. It now has 148,000. As far as I know the Optispark ,ICM and timing components are original to the car. Plug wires(Duraspark) and coil (MSD)were replaced about 3 years ago.
Common sense tells me that if this was a timing chain issue I would have more consistent starting issues.
When the car is running it makes no difference if it is hot or cold,open loop or closed loop I get the mid-range knock,detonation.
Plug wires I have not checked yet. After 3 years I guess it wouldn't hurt to just replace them. When I replaced them they went back into their original locations including the shields.
Again thanks for the input
and I will post updates as this progresses.
I need to add some things that I left out in my original post. No I do not have a scanner. I can only go by what I hear and feel as far as knock retard. Now that I think about it as heavy as the knock,detonation is, clearly audible, and how badly it falls on it's face I am only assuming that it has reached the limits of knock retard.
Also I should clarify the "rough start" condition I mentioned. Usually it starts with a quarter turn of the starter. More times than not it will start normally. When I experience a bad start it is almost like the starter is in a bind. It will turn over, stop for a second,and finally start. (Timing problem?),(misfire at startup?) I am starting to suspect plug wires as this only happens under load and not at normal cruise. When it does start it feels like something is hitting the floorboard from underneath. I have checked underneath for anything loose or touching the frame and found nothing. Mounts appear to be in good condition.
The car had 113,000 miles on it when I bought it. It now has 148,000. As far as I know the Optispark ,ICM and timing components are original to the car. Plug wires(Duraspark) and coil (MSD)were replaced about 3 years ago.
Common sense tells me that if this was a timing chain issue I would have more consistent starting issues.
When the car is running it makes no difference if it is hot or cold,open loop or closed loop I get the mid-range knock,detonation.
Plug wires I have not checked yet. After 3 years I guess it wouldn't hurt to just replace them. When I replaced them they went back into their original locations including the shields.
Again thanks for the input
and I will post updates as this progresses.
Last edited by Antigone; 05-18-2010 at 08:42 AM. Reason: added text
05-25-2010, 06:50 AM
#4
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Location: Texas,DFW
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Update. Frustrated.
Spent a Saturday doing the LT1 plug and wire change. If I did accomplish one thing ,it was eliminating another possibility. Other than that it did not change anything as far as how it runs. 
Plugs and wires looked a little worn but otherwise normal. I did find the red alternator wire,the one that goes to the battery, frayed against the large accessory bracket on the passenger side. Fixed that. Charging is normal, Battery checks out fine.
This thing really feels and sounds like a timing problem. Idle and full throttle seem fine, midrange and part throttle it falls flat on it's face. I would think that this rules out a mechanical problem such as a timing chain. Idle is steady,normal. Full throttle seems fine. Part throttle under load is where the problem is. I understand that the ICM can be problematic at times but there is no real way to test this other than by the process of elimination. I have not had an SES light go off since this problem started. Light is operational. I unplugged the Maf and it instantly set a code. The coil is a fairly new MSD unit. I must be getting close to the problem , I am running out of things to check.
Spent a Saturday doing the LT1 plug and wire change. If I did accomplish one thing ,it was eliminating another possibility. Other than that it did not change anything as far as how it runs. Plugs and wires looked a little worn but otherwise normal. I did find the red alternator wire,the one that goes to the battery, frayed against the large accessory bracket on the passenger side. Fixed that. Charging is normal, Battery checks out fine. This thing really feels and sounds like a timing problem. Idle and full throttle seem fine, midrange and part throttle it falls flat on it's face. I would think that this rules out a mechanical problem such as a timing chain. Idle is steady,normal. Full throttle seems fine. Part throttle under load is where the problem is. I understand that the ICM can be problematic at times but there is no real way to test this other than by the process of elimination. I have not had an SES light go off since this problem started. Light is operational. I unplugged the Maf and it instantly set a code. The coil is a fairly new MSD unit. I must be getting close to the problem , I am running out of things to check.
05-26-2010, 12:32 PM
#5
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Join Date: May 2010
Posts: 1
My car is doing the same thing and it is very frustrating. Somedays it rocks and somedays its a dog, today it was really a dog. Let us know if you make any progress.
05-26-2010, 01:02 PM
#6
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Location: Florida
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You've missed one very important and quite obvious thing to check, fuel press. at the rail. Could be a pump takin a crap, or the regulator not keeping enough pressure in the rail, which would cause drastic power loss and detonation due to leaning out. Also, could be tps, map, or ive heard of coolant temp. sensors causing strange things to happen, but never had that issue myself.
I was going to say start with the plugs and wires as well, so good choice there. At least you ruled it out. Try cleaning the MAF with sensitive electrical parts cleaner. I think advanced auto sells it. Use the spray and a q-tip but be sure not to lose any cotton on the MAF as it starts to fall apart. A malfunctioning MAF would cause an issue like this as WOT does not use the MAF for fueling, but it will at all other stages, and if its reading low airflow, you wont get enough fuel in midrange, and it too will cause a lean scenario.
I was going to say start with the plugs and wires as well, so good choice there. At least you ruled it out. Try cleaning the MAF with sensitive electrical parts cleaner. I think advanced auto sells it. Use the spray and a q-tip but be sure not to lose any cotton on the MAF as it starts to fall apart. A malfunctioning MAF would cause an issue like this as WOT does not use the MAF for fueling, but it will at all other stages, and if its reading low airflow, you wont get enough fuel in midrange, and it too will cause a lean scenario.
05-26-2010, 01:07 PM
#7
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When you are lugging the engine at moderate speed, the EGR system activates. If you still have EGR with your BBK headers, is it possible you have a problem with the pipe that runs from the headers to the intake manifold, or that the EGR valve has some sort of a leak? A correctly working EGR system will actually reduce the tendency for the engine to detonate (knock) when its being lugged at low speed in the wrong gear.
You need to get a scanner (preferably scanning software) on it, to see if its actually pulling timing when you think its suffering from knock retard. You should never actually hear detonation. The knock retard system should eliminate it before you can hear it. If the system is pulling the max of 15* reatard and you can still hear it, there's a major problem.
You need to get a scanner (preferably scanning software) on it, to see if its actually pulling timing when you think its suffering from knock retard. You should never actually hear detonation. The knock retard system should eliminate it before you can hear it. If the system is pulling the max of 15* reatard and you can still hear it, there's a major problem.
05-26-2010, 08:08 PM
#8
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Location: Texas,DFW
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Thanks for the replies . I really do appreciate it. I decided to take it off the road until I get this figured out.
Fuel pressure checks are normal. Excuse me for leaving this out. The EGR system is one that I have not checked yet. EGR valve was replaced about 3 years ago when I had the heads off to remove broken manifold bolts. Heads were repaired , cleaned and new springs and seals installed. I cleaned the intake and EGR area thouroughly before putting everything back together. New EGR valve installed not long after I got it back together. It was not running bad at the time , EGR valve was simply preventative maint. This thing has run like clockwork for the past few years. I am just assuming that the EGR system is functioning properly having low time on it. This will be the next thing I will check.
The EGR and AIR system are connected and fully functional. Hoses for these two systems are all connected and in good condition. The only items I have not checked are the EGR valve itself and the EGR solenoid.
I don't lug the engine. RPM'S are between 2 and 3 k when I expierience the problem. Usually 1/4 throtle or less.
It really does sound like valve knock when this happens. I hope that there is nothing "major" wrong here. This thing still idles at a very steady 800 RPM. Runs at 180 degress all day long and still runs ok at full throttle.
This is not a POS. Always maintained and well taken care of. It was my daily driver.
Again...........thanks so much for the replies and will update as time and money allow.
Fuel pressure checks are normal. Excuse me for leaving this out. The EGR system is one that I have not checked yet. EGR valve was replaced about 3 years ago when I had the heads off to remove broken manifold bolts. Heads were repaired , cleaned and new springs and seals installed. I cleaned the intake and EGR area thouroughly before putting everything back together. New EGR valve installed not long after I got it back together. It was not running bad at the time , EGR valve was simply preventative maint. This thing has run like clockwork for the past few years. I am just assuming that the EGR system is functioning properly having low time on it. This will be the next thing I will check.
The EGR and AIR system are connected and fully functional. Hoses for these two systems are all connected and in good condition. The only items I have not checked are the EGR valve itself and the EGR solenoid.
I don't lug the engine. RPM'S are between 2 and 3 k when I expierience the problem. Usually 1/4 throtle or less.
It really does sound like valve knock when this happens. I hope that there is nothing "major" wrong here. This thing still idles at a very steady 800 RPM. Runs at 180 degress all day long and still runs ok at full throttle.
This is not a POS. Always maintained and well taken care of. It was my daily driver.
Again...........thanks so much for the replies and will update as time and money allow.
Last edited by Antigone; 05-26-2010 at 09:06 PM. Reason: text
05-30-2010, 10:45 AM
#11
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Location: Texas,DFW
Posts: 23
Time to upgrade the toolbox.
Looking at scanners. The days of plugs points and a cap fixing everything have long gone. I have never owened one so any insight here would be very helpful. Anyone out there using these particular models? I also looked at some Code "readers" that are cheaper but I don't think that is what I need. Seems to be a lot of choices out there. I think I have narrowed it down to these 2.
Thanks.
Autoxray EZ-Scan 6000OBD I & II Code Scanner The AutoXray 6000 is an OBD I and OBD II scanner which includes all OBD II protocols, including Controller Area Network (CAN) protocol, allowing for more capability and flexibility to manage the diagnostic process.
The CAN protocol has been used in a variety of vehicles and is now mandated in all new vehicles.
Autoxray 6000 scan Collects All Values from Vehicles On-Board Computer.
•FREE INTERNET UPDATES
•Supports multiple trouble code requests, generic codes (mode 3), pending codes (mode 7), enhanced codes (mode 13).
•On-screen definitions of OBD I trouble codes, OBD II generic and OBD II manufacturer specific codes.
•Detects OBD-II Freeze Frame Information.
•Displays Readiness Test Status.
•Displays O2 Sensor Test.
•Test Results (mode 6).
•Vehicle ID (mode 9).
•Set Measurement Units in SAE/Metric.
•Live Data Stream Monitoring.
•29 Frame Capture Mode.
•Set Capture Frame Interval from 0500ms to 5000ms.
•Reset Check Engine Lights.
•Quick Step Data Navigation.
•Customize Data Views.
•Internet Upgradeable.
Autoxray 6000 VEHICLE COVERAGE:
•GM '82 - Current Year (12 & 16 pin ALDL and OBD-II),
•Ford '83 - Current Year (EEC IV and OBD-II),
•Chrysler '83 - Current Year (SCI and OBD-II),
•Jeep '91 - Current Year (SCI and OBD-II),
•Toyota '96 - Current Year (OBD-II),
•Honda '96 - Current Year (OBD-II),
•NISSAN '96 - Current Year (OBD-II),
•All other Asian and European '96 - Current Year (OBD-II)
CONTENTS: Autoxray 6000 Scanner, GM OBD-I Cable, Ford OBD-I Cable, Chrysler OBD-I Cable, OBD-II Cable (Yellow), OBD-II MFG Specific Cable, EZ-PC, Case, Users Manual, Reg. Card
EZ-PC (Included) - Internet Upgrades, Graph Drivability Capture Data, Achieve Scan & Capture information, Print reports, Export Capture Data in Spreadsheet Format Autoxray 6000
-------------------------------------------------------------------------
Actron CP9150 SUPER AutoScanner
Actron CP9150 SUPER Auto Scanner Kit W/OBD II
The CP9150 is the same unit as the CP9145 but it includes ALDL, EEC-IV & SCI cables plus carry case.
A bold step forward in DIY diagnostics! The Actron SUPER AutoScanner allows you to easily retrieve and read OBD I and/or II trouble codes and display/read live vehicle data for a faster diagnosis. This sophisticated yet extremely user-friendly tool can be used on OBD I & II compliant cars and light trucks sold in the U.S.
•Read and erase trouble codes.
•On screen code definitions.
•Display, record and play back live data.
•Read pending codes, I/M monitors, M/L status.
•Software upgradeable.
•Universal cable included for 1996 and newer applications.
•Includes CP9145 SUPER AutoScanner, standard 8 ft.
•Extender Cable and standard OBD II Adapter Cable.
•Also includes CP9127 GM ALDL Cable Kit, CP9128 Ford MCU/EEC-IV Cable Kit, CP9129 Chrysler SCI Cable Kit(For OBD I Applications). CP9133 Hard Plastic Carrying Case.
Looking at scanners. The days of plugs points and a cap fixing everything have long gone. I have never owened one so any insight here would be very helpful. Anyone out there using these particular models? I also looked at some Code "readers" that are cheaper but I don't think that is what I need. Seems to be a lot of choices out there. I think I have narrowed it down to these 2.
Thanks.
Autoxray EZ-Scan 6000OBD I & II Code Scanner The AutoXray 6000 is an OBD I and OBD II scanner which includes all OBD II protocols, including Controller Area Network (CAN) protocol, allowing for more capability and flexibility to manage the diagnostic process.
The CAN protocol has been used in a variety of vehicles and is now mandated in all new vehicles.
Autoxray 6000 scan Collects All Values from Vehicles On-Board Computer.
•FREE INTERNET UPDATES
•Supports multiple trouble code requests, generic codes (mode 3), pending codes (mode 7), enhanced codes (mode 13).
•On-screen definitions of OBD I trouble codes, OBD II generic and OBD II manufacturer specific codes.
•Detects OBD-II Freeze Frame Information.
•Displays Readiness Test Status.
•Displays O2 Sensor Test.
•Test Results (mode 6).
•Vehicle ID (mode 9).
•Set Measurement Units in SAE/Metric.
•Live Data Stream Monitoring.
•29 Frame Capture Mode.
•Set Capture Frame Interval from 0500ms to 5000ms.
•Reset Check Engine Lights.
•Quick Step Data Navigation.
•Customize Data Views.
•Internet Upgradeable.
Autoxray 6000 VEHICLE COVERAGE:
•GM '82 - Current Year (12 & 16 pin ALDL and OBD-II),
•Ford '83 - Current Year (EEC IV and OBD-II),
•Chrysler '83 - Current Year (SCI and OBD-II),
•Jeep '91 - Current Year (SCI and OBD-II),
•Toyota '96 - Current Year (OBD-II),
•Honda '96 - Current Year (OBD-II),
•NISSAN '96 - Current Year (OBD-II),
•All other Asian and European '96 - Current Year (OBD-II)
CONTENTS: Autoxray 6000 Scanner, GM OBD-I Cable, Ford OBD-I Cable, Chrysler OBD-I Cable, OBD-II Cable (Yellow), OBD-II MFG Specific Cable, EZ-PC, Case, Users Manual, Reg. Card
EZ-PC (Included) - Internet Upgrades, Graph Drivability Capture Data, Achieve Scan & Capture information, Print reports, Export Capture Data in Spreadsheet Format Autoxray 6000
-------------------------------------------------------------------------
Actron CP9150 SUPER AutoScanner
Actron CP9150 SUPER Auto Scanner Kit W/OBD II
The CP9150 is the same unit as the CP9145 but it includes ALDL, EEC-IV & SCI cables plus carry case.
A bold step forward in DIY diagnostics! The Actron SUPER AutoScanner allows you to easily retrieve and read OBD I and/or II trouble codes and display/read live vehicle data for a faster diagnosis. This sophisticated yet extremely user-friendly tool can be used on OBD I & II compliant cars and light trucks sold in the U.S.
•Read and erase trouble codes.
•On screen code definitions.
•Display, record and play back live data.
•Read pending codes, I/M monitors, M/L status.
•Software upgradeable.
•Universal cable included for 1996 and newer applications.
•Includes CP9145 SUPER AutoScanner, standard 8 ft.
•Extender Cable and standard OBD II Adapter Cable.
•Also includes CP9127 GM ALDL Cable Kit, CP9128 Ford MCU/EEC-IV Cable Kit, CP9129 Chrysler SCI Cable Kit(For OBD I Applications). CP9133 Hard Plastic Carrying Case.
Last edited by Antigone; 07-29-2010 at 05:05 PM. Reason: text
06-01-2010, 10:57 PM
#12
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Location: ABQ, NM
Posts: 437
no idea what kind of price tag that runs, but if you have a laptop you can get TC/datamaster/aldl for like $250. And if you don't want to play with the tuning side and only datalog, just get the ALDL cable ($80) and use freescan or datamaster.
06-02-2010, 03:55 AM
#13
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Join Date: May 2010
Location: Texas,DFW
Posts: 23
Both about the same as far as price. Around $250.00 I don't see me needing to do any tuning with a laptop,which I don't have. Scanner maybe a better option for my case? Just trying to get a little feedback on what some of you are using. Never owned a scanner and want to make sure I get something that works. Thanks for the input.
06-14-2010, 05:45 AM
#14
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Join Date: May 2010
Location: Texas,DFW
Posts: 23
Update. Took the car to have it scanned/diagnosed. No stored codes. Engine has a crossfire problem #3 cylinder. That would explain the heavy " knock" I mentioned in the original post. I suspect carbon tracking in the cap. Shop suggested I could try a cap and rotor only replacement but that sounds like false economy to me. They are asking $1000.00 to replace with a new AC/Delco optispark unit. Needless to say I'll do some shopping around and do the work myself. Thanks to everyone who helped here and I'll post the fix when it gets done.
07-29-2010, 08:30 PM
#15
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Join Date: May 2010
Location: Texas,DFW
Posts: 23
Optispark Post Mortem
With the problem solved I wanted to close this thread. I want to thank everyone that helped. I hope any information can help or be of some use to someone down the road.
1.As you can see from the first photo the bearing was in very bad shape. Almost locked up and a few of the ball bearings had fallen out.
2.The second image of the inside of the cap shows the carbon tracking I suspected in a previous post.
3.The third image of the rotor shows the heavy wear to the rotor tip.
All of these combined and it was a wonder that it would run at all.
New Distributor, cap and rotor were installed. First Optispark change for me. Not complicated but it is time consuming. The car runs great. Fired right up and runs so much smoother.
Again thanks to everyone who posted in this thread.............now on to the next project.
1.As you can see from the first photo the bearing was in very bad shape. Almost locked up and a few of the ball bearings had fallen out.
2.The second image of the inside of the cap shows the carbon tracking I suspected in a previous post.
3.The third image of the rotor shows the heavy wear to the rotor tip.
All of these combined and it was a wonder that it would run at all.
New Distributor, cap and rotor were installed. First Optispark change for me. Not complicated but it is time consuming. The car runs great. Fired right up and runs so much smoother.
Again thanks to everyone who posted in this thread.............now on to the next project.
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