Posted: Wed May 14, 2008 9:14
So I started doing runs tonight at around 1030pm for Christian over at Cobb so he could see the fuel cut I was experiencing. Boy did that turn into a long night of datalogging.
So Here's the main link
http://www.mazdaspeedforums.org/forum/mazd...d-5th-gear.html
Some points from this are..
Originally Posted by Joshj84 View Post
Because everytime I hit this 'cut' my fuel pressure and maf voltage drop at the same time.
I still believe you are hitting a "boost limit" fuel cut. I understand that you are seeing these drops in fuel pressure and MAF voltage, but we need to discover what is causal and what is reactionary from the ECU...what is the variable that is actually causing this behavior. This is what we need to look for. The stock ECU is programmed to have varying boost cut values based on several different parameters and the stock ECU is very aggressive with lowering the boost limits with atmospheric pressure (elevation) changes. If this is on a stock ECU program, then I believe you are realizing how aggressive the stock programming is. The solution is not simple either since the boost limit values are not a simple parameter, the boost cut value varies with several other variables.
Christian.
Originally Posted by Joshj84 View Post
Christian what would you like me to try and find? I can get datalogs for any parameter that dashhawk offers.
I don't need you to find anything for now. I am relatively confident that you are simply exceeding a boost limit value and the ECU is doing what it has been programmed to do. Our calibrations are not designed for a catless exhaust system or a system that relieves exhaust gas back-pressure to an excessive point. The car has several limits set and we may simply need to see what limits you are hitting; whether they be load, boost, torque, etc. Our calibrations are better optimized IMO, but me saying that makes it sound like a sales pitch...it is not. Below are some notes from our MS3 Map notes:
"Hardware Requirements: Otherwise stock vehicle with a STOCK INTAKE SYSTEM, STOCK FUEL INJECTORS ONLY, tested with a Cobb Tuning turboback exhaust system with high-flow catalytic converter. An equivalent turbo-back exhaust system could be used. If the turboback exhaust system relieves back-pressure to an excessive point boost creep is possible. If a lesser flowing turbo-back exhaust system is used then boost targets may not be achievable. The addition of any other hardware may make the vehicle perform poorly."
Nothing positive, but I am relatively confident that you have allowed your exhaust system to flow more freely than stock and the stock EMS programming you are operating the engine with has not been programmed to understand this mechanical change. This excessive relief in post-turbo back pressure is allowing the turbo to overrun, and you are most likely exceeding a stock boost limit for an extended period of time. The ECU is telling you this and taking protective measures to promote engine longevity. If you see that the WGDC is at 0% while you are accelerating at WOT, then this is telling us that the ECU is trying to lower boost to bring the boost values back to target. Can you give me a better idea of what your WGDC is doing under acceleration (Please do this in a safe environment like the track)?
Christian.
Originally Posted by Haltech View Post
the easiest, cheapest solution for you to determine if its boost cut or fuel cut, is to solder in a map clamp. Once you set the voltage on the clamp, you will know for sure once you start driving it.
I would not suggest that since that sensor's input is used heavily inside the ECU to make various other calculations. Once you clamp that signal you effectively force the ECU to run blind with a major sensor input, and any calculations using this component are no longer accurate. The ECU code extensively uses the MAP sensor signal. We should be able to get an idea about what the ECU is doing or trying to do by viewing some additional datalogs.
As far as my analysis of your logs. It appears that my speculations may be correct. The ECU is going to remove WGDC if it thinks the turbo is exceeding a programmed limit. You can clearly see this in your logs. You are requesting more torque by depressing your gas pedal...yet WGDC is going to 0%. This leads me to believe that your ECU is shutting down its boost control system (WGDC) in order to bring the turbo back under control, to bring boost down to a desired target, or to pull boost back from a set safety limit. This is part of the standard PID controls inside the ECU. Essentially, the ECU has a certain amount of "authority" to add and remove WGDC in order to achieve programmed targets. This log is telling me that your ECU is doing everything within it's authority to remove boost...to the point where the WG controls are turned off (0% WGDC). The ECU has not been programmed to understand that your car is running a catless exhaust.
Several solutions are possible:
1) Install a high-flow catalytic converter that creates some post-turbo exhaust gas back pressure. A well designed cat will not compromise power and this is much better on the environment.
2) You would need to drill the hole in your restrictor pill to a larger size, but this may be a PIA since the stock restrictor pill is pressed into the turbo pressure port. We have composed a document detailing additional specifications of the stock MS3 boost control system configuration.
3) Program the EMS to understand the hardware that is installed on your car.
This is a normal phenomenon and we have seen this in other ECUs (Subaru, Mitsubishi, Nissan, etc.). The ideal solution is a properly calibrated EMS reflash.
Christian.
Now when you look at the graph look at the red line you'll see it drop before everything and thats the ECU pulling boost.
So in reality its more a boost issue than a fuel issue at this time. Not saying an upgraded fuel pump wont help but airs just very thin up here.
So Here's the main link
http://www.mazdaspeedforums.org/forum/mazd...d-5th-gear.html
Some points from this are..
Originally Posted by Joshj84 View Post
Because everytime I hit this 'cut' my fuel pressure and maf voltage drop at the same time.
I still believe you are hitting a "boost limit" fuel cut. I understand that you are seeing these drops in fuel pressure and MAF voltage, but we need to discover what is causal and what is reactionary from the ECU...what is the variable that is actually causing this behavior. This is what we need to look for. The stock ECU is programmed to have varying boost cut values based on several different parameters and the stock ECU is very aggressive with lowering the boost limits with atmospheric pressure (elevation) changes. If this is on a stock ECU program, then I believe you are realizing how aggressive the stock programming is. The solution is not simple either since the boost limit values are not a simple parameter, the boost cut value varies with several other variables.
Christian.
Originally Posted by Joshj84 View Post
Christian what would you like me to try and find? I can get datalogs for any parameter that dashhawk offers.
I don't need you to find anything for now. I am relatively confident that you are simply exceeding a boost limit value and the ECU is doing what it has been programmed to do. Our calibrations are not designed for a catless exhaust system or a system that relieves exhaust gas back-pressure to an excessive point. The car has several limits set and we may simply need to see what limits you are hitting; whether they be load, boost, torque, etc. Our calibrations are better optimized IMO, but me saying that makes it sound like a sales pitch...it is not. Below are some notes from our MS3 Map notes:
"Hardware Requirements: Otherwise stock vehicle with a STOCK INTAKE SYSTEM, STOCK FUEL INJECTORS ONLY, tested with a Cobb Tuning turboback exhaust system with high-flow catalytic converter. An equivalent turbo-back exhaust system could be used. If the turboback exhaust system relieves back-pressure to an excessive point boost creep is possible. If a lesser flowing turbo-back exhaust system is used then boost targets may not be achievable. The addition of any other hardware may make the vehicle perform poorly."
Nothing positive, but I am relatively confident that you have allowed your exhaust system to flow more freely than stock and the stock EMS programming you are operating the engine with has not been programmed to understand this mechanical change. This excessive relief in post-turbo back pressure is allowing the turbo to overrun, and you are most likely exceeding a stock boost limit for an extended period of time. The ECU is telling you this and taking protective measures to promote engine longevity. If you see that the WGDC is at 0% while you are accelerating at WOT, then this is telling us that the ECU is trying to lower boost to bring the boost values back to target. Can you give me a better idea of what your WGDC is doing under acceleration (Please do this in a safe environment like the track)?
Christian.
Originally Posted by Haltech View Post
the easiest, cheapest solution for you to determine if its boost cut or fuel cut, is to solder in a map clamp. Once you set the voltage on the clamp, you will know for sure once you start driving it.
I would not suggest that since that sensor's input is used heavily inside the ECU to make various other calculations. Once you clamp that signal you effectively force the ECU to run blind with a major sensor input, and any calculations using this component are no longer accurate. The ECU code extensively uses the MAP sensor signal. We should be able to get an idea about what the ECU is doing or trying to do by viewing some additional datalogs.
As far as my analysis of your logs. It appears that my speculations may be correct. The ECU is going to remove WGDC if it thinks the turbo is exceeding a programmed limit. You can clearly see this in your logs. You are requesting more torque by depressing your gas pedal...yet WGDC is going to 0%. This leads me to believe that your ECU is shutting down its boost control system (WGDC) in order to bring the turbo back under control, to bring boost down to a desired target, or to pull boost back from a set safety limit. This is part of the standard PID controls inside the ECU. Essentially, the ECU has a certain amount of "authority" to add and remove WGDC in order to achieve programmed targets. This log is telling me that your ECU is doing everything within it's authority to remove boost...to the point where the WG controls are turned off (0% WGDC). The ECU has not been programmed to understand that your car is running a catless exhaust.
Several solutions are possible:
1) Install a high-flow catalytic converter that creates some post-turbo exhaust gas back pressure. A well designed cat will not compromise power and this is much better on the environment.
2) You would need to drill the hole in your restrictor pill to a larger size, but this may be a PIA since the stock restrictor pill is pressed into the turbo pressure port. We have composed a document detailing additional specifications of the stock MS3 boost control system configuration.
3) Program the EMS to understand the hardware that is installed on your car.
This is a normal phenomenon and we have seen this in other ECUs (Subaru, Mitsubishi, Nissan, etc.). The ideal solution is a properly calibrated EMS reflash.
Christian.
Now when you look at the graph look at the red line you'll see it drop before everything and thats the ECU pulling boost.
So in reality its more a boost issue than a fuel issue at this time. Not saying an upgraded fuel pump wont help but airs just very thin up here.
