What would cause a car to knock?
Naji, you should be able to tune out most of the knock, just go back and look at my log. I pretty much only get knock counts starting at ~3500 and die off at ~4500. The rest of the rev range is pretty clean.
Yes, the factory tune was for 93, but that doesn't mean you can't tune it to run 91. There is nothing mechanical about the car which makes it unable to run 91. So the options are to alter timing, fueling, and/or boost.
You may not WANT to pull more timing, but it'll probably get rid of the knock.
Yes, the factory tune was for 93, but that doesn't mean you can't tune it to run 91. There is nothing mechanical about the car which makes it unable to run 91. So the options are to alter timing, fueling, and/or boost.
You may not WANT to pull more timing, but it'll probably get rid of the knock.
nj1266-
If this has been asked already, I apologize. I didn't read every post in the thread. Is your XEDE in pass through? You can't run zero timing values with pump gas if any of your fueling is controlled in the XEDE. Even though your ECUflash rom might be conservative, you have to address all your tuning methods.
If the XEDE is out of the car, disregard. If not, I'd like to see your XEDE map to try to help you out. Tuning it is substantially different than tuning ECUflash.
Seth
If this has been asked already, I apologize. I didn't read every post in the thread. Is your XEDE in pass through? You can't run zero timing values with pump gas if any of your fueling is controlled in the XEDE. Even though your ECUflash rom might be conservative, you have to address all your tuning methods.
If the XEDE is out of the car, disregard. If not, I'd like to see your XEDE map to try to help you out. Tuning it is substantially different than tuning ECUflash.
Seth
Start at 5500 RPM first, do another run. Look where knock starts again and keep working from there.
Eric
nj1266-
If this has been asked already, I apologize. I didn't read every post in the thread. Is your XEDE in pass through? You can't run zero timing values with pump gas if any of your fueling is controlled in the XEDE. Even though your ECUflash rom might be conservative, you have to address all your tuning methods.
If the XEDE is out of the car, disregard. If not, I'd like to see your XEDE map to try to help you out. Tuning it is substantially different than tuning ECUflash.
Seth
If this has been asked already, I apologize. I didn't read every post in the thread. Is your XEDE in pass through? You can't run zero timing values with pump gas if any of your fueling is controlled in the XEDE. Even though your ECUflash rom might be conservative, you have to address all your tuning methods.
If the XEDE is out of the car, disregard. If not, I'd like to see your XEDE map to try to help you out. Tuning it is substantially different than tuning ECUflash.
Seth
This is not on my car. This is a friend's car that has cams, TBE, and a drop-in. It was flashed by a socal tuner twice and he could not get it right. The tuner gave up on the car, but I am not going to give up just yet.
My car does not run on 91 octane, it is against my religion
Guys,
I have a question to ask. I was looking @ my friend's timing map and noticed that the timing in the 0-40 load and 0-1000 rpm has the timing set @ 10*. Stock it is set @ 5*. Why would the tuner do that? What is the point of doubling up the timing in that region?
Thanks
I have a question to ask. I was looking @ my friend's timing map and noticed that the timing in the 0-40 load and 0-1000 rpm has the timing set @ 10*. Stock it is set @ 5*. Why would the tuner do that? What is the point of doubling up the timing in that region?
Thanks
Guys,
I have a question to ask. I was looking @ my friend's timing map and noticed that the timing in the 0-40 load and 0-1000 rpm has the timing set @ 10*. Stock it is set @ 5*. Why would the tuner do that? What is the point of doubling up the timing in that region?
Thanks
I have a question to ask. I was looking @ my friend's timing map and noticed that the timing in the 0-40 load and 0-1000 rpm has the timing set @ 10*. Stock it is set @ 5*. Why would the tuner do that? What is the point of doubling up the timing in that region?
Thanks
I cant take credit for the advanced timing at idle a tuner here in SoCal told me how to smooth the idle out. It also helps if he has cam gears to use different settings ie -3/-2. Mine are set at -2/-2.
If the timing in the XEDE is that high, that is 100% what is causing the knock. Set the timing in the XEDE at -2 (NEGATIVE 2) globally. If you don't know what I'm talking about, bypass the XEDE and send me a PM so I can call you.
Remember, it works in offsets, not static timing. If it has a positive value, its adding to your flash- Not a good thing, plus it will create P0300s. If its zeroed and any fuel is pulled in XMAP, it is probably still too much timing.
Remember, it works in offsets, not static timing. If it has a positive value, its adding to your flash- Not a good thing, plus it will create P0300s. If its zeroed and any fuel is pulled in XMAP, it is probably still too much timing.
Last edited by Noize; Feb 16, 2007 at 05:12 PM.
knock(detonation and/or pre-ignition) can be caused by one or more of many different factors. As most of you know the usual suspects.
Here is a run down of what "knock" is.
Pre-ignition
* Defined as: ignition of the air/fuel mixture before the pre-set ignition timing mark
* Caused by hot spots in the combustion chamber...can be caused
(or amplified) by over advanced timing, too hot a spark plug, low octane fuel, lean air/fuel mixture, too high compression, or insufficient engine cooling
* A change to a higher octane fuel, a colder plug, richer fuel mixture,
or lower compression may be in order
* You may also need to retard ignition timing, and check vehicle's cooling system
* Pre-ignition usually leads to detonation; pre-ignition an detonation are two separate events
Detonation
* The spark plug's worst enemy! (Besides fouling)
* Can break insulators or break off ground electrodes
* Pre-ignition most often leads to detonation
* Plug tip temperatures can spike to over 3000°F during the combustion process (in a racing engine)
* Most frequently caused by hot spots in the combustion chamber.
Hot spots will allow the air/fuel mixture to pre-ignite. As the piston is being forced upward by mechanical action of the connecting rod, the pre-ignited explosion will try to force the piston downward. If the piston can't go up (because of the force of the premature explosion) and it can't go down (because of the upward mo-tion of the connecting rod), the piston will rattle from side to side. The resulting shock wave causes an audible pinging sound. This is detonation.
* Most of the damage than an engine sustains when "detonating" is from excessive heat
* The spark plug is damaged by both the elevated temperatures and the accompanying shock wave, or concussion
For those of you that think you should lean the AFR's when encountering knock, this is the exact opposite of what you should do(besides pull ignition timing). Example, some piggyback units(AFC MAP sensor clamps) on N/A cars gone turbo uses this to their advantage. The AFC can alter injector pulse width to alter fuel delivery, causing the AFR's to altered. Most companies that sell turbo kits for N/A engines that use a speed density ECU(using a MAP sensor) cannot retard ignition timing on their own, using a simple AFC, and therefore use the stock ignition timing tables(on mild boost). They reley on two things to combat knock, one is really rich AFR's to "drown" out the knock and keep cylinder temps and pressures down. The other is to allow the stock knock sensor and the ECU's stock knock sensor protocols to retard ignition timing when knock is encountered. Although this works(only on very low boost pressures and low effective compression ratios), it's not the correct way to tune, but it proves my point that richning the mixture will help combat knock because of the fuel's cooling effects. BUT, one must figure out what the cause of detonation and/or pre-ignition is first.
Obviously, mechanical knock may be the case, pre-ignition can be caused by flashing on the head or a spur on the piston face. These type of things will get much hotter than the surrounding areas and cause the mixture to ignite before the pre-set ignition from the plug.
Like stated above, plugs that are too hot a heat range will not allow for the heat to escape the combustion chamber. The plug has two main purposes. Ignite the air/fuel mixture and transfer heat from the combustion chamber. It's important to remember spark plugs do not create heat, they only remove heat. The spark plug works as a heat exchanger by pulling unwanted thermal energy away from the combustion chamber, and transferring the heat to the engine's cooling
system. The heat range is defined as a plug's ability to dissipate heat. Make sure the plugs are properly torqued as a improper seat will not allow heat to transfer to the head. The temperature of the spark plug's firing end must be kept low enough to prevent pre-ignition, but high enough to prevent fouling. This is called "Thermal Performance", and is determined by the heat range selected. The insulator nose length, gas volume around the insulator nose, the materials/construction of the center electrode and porcelain insulator all determine the plugs heat range. Improper gap can play a huge roll in knock as well. You want to run the most gap possible to better expose the spark to the ignition, but if you run too large of a gap, you will have misfires. If you run too small of a gap, you will increase firing end temp and thus combustion temps/pressures. you must reduce the gap about .004" for every 50 hp you add as a general rule of thumb.
Another thing to think about is oil in the combustion chamber, either in the mixture(crankcase venilation, bad turbo seals or other means) or from blow-by from the piston rings. If oil is present in the combustion chamber, it effectively lowers the detonation threshold and can and most times will cause knock when ignition timing is advanced right up to the detonation threshold on a particular octane with no oil present.
A bad injector can cause the respective cylinder to run lean and can cause knock and engine damage.
High EGT's from a exhaust restriction or ignition timing thats way too retarded can cause EGT's to spike and actually cause knock.
improper cam overlap that is raising static compression can cause knock.
In short, there are many factors, keep troubleshooting until you nail it down.
CJ
p.s. to check for overadvanced ignition timing, pull ignition timing two degs in the effected area, if knock is still present, pull timing another two degs. If it's gone, advance timing a deg at a time until knock is encountered again in that area, then retard ignition timing 2-3 degs in that area and leave it there. This will tell you if it's overadvanced ignition timing or mechanical knock(hotspots..ect.) Also verify that AFR's are correct in that area and are not too lean(once you have decided all your injectors are good and there is not fuel delivery problem for each cylinder). If ignition timing has to be pulled significantly in that area, and is about 4-6degs less than it should be for that area, you need to look for other issues causing the knock.
Here is a run down of what "knock" is.
Pre-ignition
* Defined as: ignition of the air/fuel mixture before the pre-set ignition timing mark
* Caused by hot spots in the combustion chamber...can be caused
(or amplified) by over advanced timing, too hot a spark plug, low octane fuel, lean air/fuel mixture, too high compression, or insufficient engine cooling
* A change to a higher octane fuel, a colder plug, richer fuel mixture,
or lower compression may be in order
* You may also need to retard ignition timing, and check vehicle's cooling system
* Pre-ignition usually leads to detonation; pre-ignition an detonation are two separate events
Detonation
* The spark plug's worst enemy! (Besides fouling)
* Can break insulators or break off ground electrodes
* Pre-ignition most often leads to detonation
* Plug tip temperatures can spike to over 3000°F during the combustion process (in a racing engine)
* Most frequently caused by hot spots in the combustion chamber.
Hot spots will allow the air/fuel mixture to pre-ignite. As the piston is being forced upward by mechanical action of the connecting rod, the pre-ignited explosion will try to force the piston downward. If the piston can't go up (because of the force of the premature explosion) and it can't go down (because of the upward mo-tion of the connecting rod), the piston will rattle from side to side. The resulting shock wave causes an audible pinging sound. This is detonation.
* Most of the damage than an engine sustains when "detonating" is from excessive heat
* The spark plug is damaged by both the elevated temperatures and the accompanying shock wave, or concussion
For those of you that think you should lean the AFR's when encountering knock, this is the exact opposite of what you should do(besides pull ignition timing). Example, some piggyback units(AFC MAP sensor clamps) on N/A cars gone turbo uses this to their advantage. The AFC can alter injector pulse width to alter fuel delivery, causing the AFR's to altered. Most companies that sell turbo kits for N/A engines that use a speed density ECU(using a MAP sensor) cannot retard ignition timing on their own, using a simple AFC, and therefore use the stock ignition timing tables(on mild boost). They reley on two things to combat knock, one is really rich AFR's to "drown" out the knock and keep cylinder temps and pressures down. The other is to allow the stock knock sensor and the ECU's stock knock sensor protocols to retard ignition timing when knock is encountered. Although this works(only on very low boost pressures and low effective compression ratios), it's not the correct way to tune, but it proves my point that richning the mixture will help combat knock because of the fuel's cooling effects. BUT, one must figure out what the cause of detonation and/or pre-ignition is first.
Obviously, mechanical knock may be the case, pre-ignition can be caused by flashing on the head or a spur on the piston face. These type of things will get much hotter than the surrounding areas and cause the mixture to ignite before the pre-set ignition from the plug.
Like stated above, plugs that are too hot a heat range will not allow for the heat to escape the combustion chamber. The plug has two main purposes. Ignite the air/fuel mixture and transfer heat from the combustion chamber. It's important to remember spark plugs do not create heat, they only remove heat. The spark plug works as a heat exchanger by pulling unwanted thermal energy away from the combustion chamber, and transferring the heat to the engine's cooling
system. The heat range is defined as a plug's ability to dissipate heat. Make sure the plugs are properly torqued as a improper seat will not allow heat to transfer to the head. The temperature of the spark plug's firing end must be kept low enough to prevent pre-ignition, but high enough to prevent fouling. This is called "Thermal Performance", and is determined by the heat range selected. The insulator nose length, gas volume around the insulator nose, the materials/construction of the center electrode and porcelain insulator all determine the plugs heat range. Improper gap can play a huge roll in knock as well. You want to run the most gap possible to better expose the spark to the ignition, but if you run too large of a gap, you will have misfires. If you run too small of a gap, you will increase firing end temp and thus combustion temps/pressures. you must reduce the gap about .004" for every 50 hp you add as a general rule of thumb.
Another thing to think about is oil in the combustion chamber, either in the mixture(crankcase venilation, bad turbo seals or other means) or from blow-by from the piston rings. If oil is present in the combustion chamber, it effectively lowers the detonation threshold and can and most times will cause knock when ignition timing is advanced right up to the detonation threshold on a particular octane with no oil present.
A bad injector can cause the respective cylinder to run lean and can cause knock and engine damage.
High EGT's from a exhaust restriction or ignition timing thats way too retarded can cause EGT's to spike and actually cause knock.
improper cam overlap that is raising static compression can cause knock.
In short, there are many factors, keep troubleshooting until you nail it down.
CJ
p.s. to check for overadvanced ignition timing, pull ignition timing two degs in the effected area, if knock is still present, pull timing another two degs. If it's gone, advance timing a deg at a time until knock is encountered again in that area, then retard ignition timing 2-3 degs in that area and leave it there. This will tell you if it's overadvanced ignition timing or mechanical knock(hotspots..ect.) Also verify that AFR's are correct in that area and are not too lean(once you have decided all your injectors are good and there is not fuel delivery problem for each cylinder). If ignition timing has to be pulled significantly in that area, and is about 4-6degs less than it should be for that area, you need to look for other issues causing the knock.
Last edited by iTune; Feb 16, 2007 at 09:30 PM.
Update
I just wanted to update you guys about our progress. Basically, the problem is solved.
We did a boost leak test on the car and there were three leaks where the boost controller was installed. The shop did not bother zip tie the hoses to secure them to the MBC and the t-fitting that was used. How hard is it to use zip ties for added security
Fixing the leak did NOT stop the knock, however. The car continued to register 8 counts of knock @ the mid range to top end.
Finally, I decided to flash the ECU with my very conservative flash. I used 2* @ peak boost/torque and not more than 13* @ 7000+ rpm. I also set the AFR on the rich side @ 10.8-10.6:1 and tapered it down below that @ 7000+ rpm.
The car LOVED this set-up and all the knock in the upper mid range went away. There was still occaisonal 3 counts of knock @ tip in, but I think I know what is going on and I will solve that too.
I also did DLL power log and compared it to the tune that the shop created. To my surprise the car produced as much power in the lower and end and better power @ the top end. It turns out that the "tooner" was trying to force 17* timing down the engine's throat when the ECU was pulling the timing back to 13*. The ECU was telling the "tooner" what to do, but he was not listening. He was insistening on making the car fit his base map, rather than give the car what it wanted.
Now that knock is eliminated, I will proceed to lean out the car and see how much power I can get out of it even though I hate 91 octane gas. But the gas prices are such that even I have been forced to use it
The owner of the car also decided to post publicly about the shop. The shop is Tuning Technologies in Colton, CA.
http://www.socalevo.net/index.php?op...&topic=39874.0
I want to thank everyone that helped out with this thread. All of those that send me maps to learn from, I say THANK YOU. All of those that made suggestions, I say THANK YOU.
We did a boost leak test on the car and there were three leaks where the boost controller was installed. The shop did not bother zip tie the hoses to secure them to the MBC and the t-fitting that was used. How hard is it to use zip ties for added security
Fixing the leak did NOT stop the knock, however. The car continued to register 8 counts of knock @ the mid range to top end.
Finally, I decided to flash the ECU with my very conservative flash. I used 2* @ peak boost/torque and not more than 13* @ 7000+ rpm. I also set the AFR on the rich side @ 10.8-10.6:1 and tapered it down below that @ 7000+ rpm.
The car LOVED this set-up and all the knock in the upper mid range went away. There was still occaisonal 3 counts of knock @ tip in, but I think I know what is going on and I will solve that too.
I also did DLL power log and compared it to the tune that the shop created. To my surprise the car produced as much power in the lower and end and better power @ the top end. It turns out that the "tooner" was trying to force 17* timing down the engine's throat when the ECU was pulling the timing back to 13*. The ECU was telling the "tooner" what to do, but he was not listening. He was insistening on making the car fit his base map, rather than give the car what it wanted.
Now that knock is eliminated, I will proceed to lean out the car and see how much power I can get out of it even though I hate 91 octane gas. But the gas prices are such that even I have been forced to use it
The owner of the car also decided to post publicly about the shop. The shop is Tuning Technologies in Colton, CA.
http://www.socalevo.net/index.php?op...&topic=39874.0
I want to thank everyone that helped out with this thread. All of those that send me maps to learn from, I say THANK YOU. All of those that made suggestions, I say THANK YOU.
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