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VF's programing is NOT 10.5:1. Either there is a problem with your setup or the a/f gauge used is incorrect. Take your scanner and look at the after cat O3 sensors at WOT near readline. Let me know what voltage they read. Changing your pulley size will not change your a/f ratio enough to matter.
You should learn the story before starting to blame others for your problems.
LOL!!!!
How is my a/f incorrect? Its reading the same from the 02's and the dyno wideband...its spot on.....How do you know its not 10.5? A lot of companies do this to prevent problems to avoid warranties. Seen it time and time again on too many vehicles. Is your porsche supercharged? How many supercharged 996's have you dyno'd? Because you sound as if you're talking with many years of experience in this category.....
Point being is, this shop is good, I'm telling you, with several long term Porsche mechanics. In fact, I'd rate them as one of the best shops in the country, and i've been to a LOT of shops. They also are featured in several magazines as being the first company to get the new Genesis over 450rwhp and into the low 11's down the track. They also were the first company to start making internal engine parts for the car including billet rods. They know what they're doing, they tuned my supra to 1,050rwhp...u telling me my tuner doesn't know his **** when he can tune something to that caliber?
I'm not changing my pulley size to change my afr...I NEVER said that so I'm not exactly sure where you got that from. I'm not a newbie at this, I'm changing the pulley size to create MORE BOOST, the tuning software my shop is getting from GIAC is what they'll be using to change my air fuels.........
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Last edited by brandongt3; 10-23-2009 at 05:38 PM.
How is my a/f incorrect? Its reading the same from the 02's and the dyno wideband.....
I'm not changing my pulley size to change my afr....I'm not a newbie at this, I'm changing the pulley size to create MORE BOOST, the tuning software my shop is getting from GIAC is what they'll be using to change my air fuels.........
Then what are the O2 voltage readings? Your current program, if it is the standard program for the VF SC, DOES NOT target an a/f ratio of 10.5, so the problem is not the program. I doubt that your a/f ratio is even close to 10.5:1 if in fact you are producing 350 rwhp.
Last edited by 1999Porsche911; 10-23-2009 at 05:38 PM.
While i agree that changing the pulley size will not change the AFR, he did state that they were getting some revised software.
That said, the software is rarely an issue. Once its flashed it doesn't change unless the ecu is trying to compensate for a real or percieved problem. I would like to have seen the TRA and FRA numbers as well as the MAF readings and crank case vac numbers before seeing a negative post towards VF and GIAC. With those real time numbers i could easily tell what the motor is doing percisely and if there is a mechanical problem still present**
Exactly my point. Thank you. I never said that the ECU changed itself, because I know that wouldnt happen. However, I did say that VF/GIAC gave the car a rich tune to avoid supercharger warranties. This was my point of 1999 porsche saying that theres something wrong with my car, when it can be something as simple as GIAC and VF just creating a rich ass fuel map to protect their asses from **** blowing up. That's the logical explanation here.
Then what are the O2 voltage readings? Your current program, if it is the standard program for the VF SC, DOES NOT target an a/f ratio of 10.5, so the problem is not the program. I doubt that your a/f ratio is even close to 10.5:1 if in fact you are producing 350 rwhp.
Wait what? How are you saying my air fuels arn't 10.5?? Look at the dyno sheet You can see my air fuels in the high 9's and low-mid 10's through the entire powerband........
I'm not sure the 02 voltage readings, I'm sure I could get that information from the shop next time I call, being that their brand new 02's, I highly doubt that's the case.
Wait what? How are you saying my air fuels arn't 10.5?? Look at the dyno sheet You can see my air fuels in the high 9's and low-mid 10's through the entire powerband........
I'm not sure the 02 voltage readings, I'm sure I could get that information from the shop next time I call, being that their brand new 02's, I highly doubt that's the case.
The program for the 99 targets around 12.2:1 above 6000 rpm. Are you running the 99 C2 progam. If not, then all bets are off. I suspect you have a boost leak, too, based on your graph. That would cause you to run rich.
If you haven't looked at your 02 sensor voltages, then you don't know what your a/f fuel ratio is. Fact is, if your car was running 9's and 10's, you would never have gotten close to 350 rwhp.
Also, where did you measure boost from. Boost is all over the place and too low for the stock VF system.
The program for the 99 targets around 12.2:1 above 6000 rpm. Are you running the 99 C2 progam. If not, then all bets are off. I suspect you have a boost leak, too, based on your graph. That would cause you to run rich.
If you haven't looked at your 02 sensor voltages, then you don't know what your a/f fuel ratio is. Fact is, if your car was running 9's and 10's, you would never have gotten close to 350 rwhp.
Also, where did you measure boost from. Boost is all over the place and too low for the stock VF system.
Why would any program target a air/fuel ratio of 12.2 high in the rpm range? Doesnt make any sense. 12.2 is way too lean. I contacted and spoke to a team member of VF and they told me their tune will give the air/fuel ratio in the 10's under boost for safety. Go figure.
Boost was measured right as close to the intake manifold as possible, right by the throttle body, thats where VF told us to get the boost readings from.
Last edited by brandongt3; 10-24-2009 at 05:50 PM.
Why would any program target a air/fuel ratio of 12.2 high in the rpm range? Doesnt make any sense. 12.2 is way too lean. I contacted and spoke to a team member of VF and they told me their tune will give the air/fuel ratio in the 10's under boost for safety. Go figure.
Boost was measured right as close to the intake manifold as possible, right by the throttle body, thats where VF told us to get the boost readings from.
Well, the team member you talked to at VF is wrong. Additionally, many shops do not have the equipment to accurately measure an a/f ratio that changes quickly. Typical problem with their equipment is that they will always read richer except under steady load conditions.
Was your boost measured BEFORE or AFTER the throttle body? What size pulley do you have on the compressor? As I suggested before, your graph indicates that you have a vaumm leak. Have you checked all connections?
BTW: Low 12:1 ratio is not too lean. You should see around 11:1 at peak torque and leaner as engine speed increases from there.
Reasons to the dyno accuracy is suspect:
Boost shown is all over the place and does not climb at a continuous pace, indicating a bad gauge, improper monitoring location or a boost leak. A leak will obviously make the engine run extremely lean.
5 psi of boost would produce less than 330 rwhp even in the best of conditions and if in fact the a/f ratio was 10:1 as the chart indicates; you would be hard pressed to even get above 300 hp.
It appears that the dyno was taken in Green Bay Wisc which is at an altitude of just under 600 feet. Using the climate figures noted on the dyno chart the SAE of 1.00 is incorrect. It should be 97.1. This translates to a correction factor of 1.03.
My guess is that the shop used a wideband sensor and simply stuck it inside the tailpipe. This would explain why the a/f readings are so far from accurate. Without adequate heat in the exhaust, the WB will always read rich.
Conclusion: Suspect that the entire dyno is inaccurate.
Well, the team member you talked to at VF is wrong. Additionally, many shops do not have the equipment to accurately measure an a/f ratio that changes quickly. Typical problem with their equipment is that they will always read richer except under steady load conditions.
Was your boost measured BEFORE or AFTER the throttle body? What size pulley do you have on the compressor? As I suggested before, your graph indicates that you have a vaumm leak. Have you checked all connections?
BTW: Low 12:1 ratio is not too lean. You should see around 11:1 at peak torque and leaner as engine speed increases from there.
Reasons to the dyno accuracy is suspect:
Boost shown is all over the place and does not climb at a continuous pace, indicating a bad gauge, improper monitoring location or a boost leak. A leak will obviously make the engine run extremely lean.
5 psi of boost would produce less than 330 rwhp even in the best of conditions and if in fact the a/f ratio was 10:1 as the chart indicates; you would be hard pressed to even get above 300 hp.
It appears that the dyno was taken in Green Bay Wisc which is at an altitude of just under 600 feet. Using the climate figures noted on the dyno chart the SAE of 1.00 is incorrect. It should be 97.1. This translates to a correction factor of 1.03.
My guess is that the shop used a wideband sensor and simply stuck it inside the tailpipe. This would explain why the a/f readings are so far from accurate. Without adequate heat in the exhaust, the WB will always read rich.
Conclusion: Suspect that the entire dyno is inaccurate.
This coming from my tuner:
"Not only does the dyno correct for altitude, it corrects for density altitude. Density altitude is the altitude in the International Standard Atmosphere at which the air density would be equal to the actual air density at the place of observation, or, in other words, the height when measured in terms of the density of the air rather than the distance from the ground.
"Density Altitude" is the pressure altitude adjusted for non-standard temperature. Both an increase in temperature and humidity will cause a reduction in air density. Thus, in hot and humid conditions, the density altitude at a particular location may be significantly higher than the true altitude, and the opposite would be true in cool dry conditions. The dyno takes an automatic measurement of the barometric pressure and ambient air temperature together with humidity measurement ensure repeatability between tests. The wideband sensor in the tail pipe is indeed an accurate way to measure this car.
Two things: The wideband has an internal heater that WILL NOT read if it is not up to the proper temperature, and your exhaust coming out is definitely up to temp, because it cleaned the carbon right off of the copper sample tube. I have done hundreds of cars, and have closely compared number on cars that had a wideband sensor into the collector area vs tailpipe measurement, and have found that the difference is small. Maybe not negligible, but within a couple of tenths of a number. This car flatlines at 10.3, which is as low as my sensor will read. the airfuel while cruising is 14.6 to 14.7 which is exactly what it is supposed to be. This dyno is defintly accurate.
I do NASA cars which are compared to another chassis dyno at the track, because they are disqualified if they exceed a certain hp with SAE correction. We are always within 1-2hp of what they get at the track. So on a 400whp car we are disagreeing by less than 1% this tune is garbage or a magical sensor is way off and not setting a CEL. Btw the generic OBD 2 data stream looks pretty good. Fuel trims are all +or- 5% and all sensors appear to be within range."
Luke
Last edited by brandongt3; 10-28-2009 at 06:31 PM.
"Not only does the dyno correct for altitude, it corrects for density altitude. Density altitude is the altitude in the International Standard Atmosphere at which the air density would be equal to the actual air density at the place of observation, or, in other words, the height when measured in terms of the density of the air rather than the distance from the ground.
"Density Altitude" is the pressure altitude adjusted for non-standard temperature. Both an increase in temperature and humidity will cause a reduction in air density. Thus, in hot and humid conditions, the density altitude at a particular location may be significantly higher than the true altitude, and the opposite would be true in cool dry conditions. The dyno takes an automatic measurement of the barometric pressure and ambient air temperature together with humidity measurement ensure repeatability between tests. The wideband sensor in the tail pipe is indeed an accurate way to measure this car.
Two things: The wideband has an internal heater that WILL NOT read if it is not up to the proper temperature, and your exhaust coming out is definitely up to temp, because it cleaned the carbon right off of the copper sample tube. I have done hundreds of cars, and have closely compared number on cars that had a wideband sensor into the collector area vs tailpipe measurement, and have found that the difference is small. Maybe not negligible, but within a couple of tenths of a number. This car flatlines at 10.3, which is as low as my sensor will read. the airfuel while cruising is 14.6 to 14.7 which is exactly what it is supposed to be. This dyno is defintly accurate.
I do NASA cars which are compared to another chassis dyno at the track, because they are disqualified if they exceed a certain hp with SAE correction. We are always within 1-2hp of what they get at the track. So on a 400whp car we are disagreeing by less than 1% this tune is garbage or a magical sensor is way off and not setting a CEL. Btw the generic OBD 2 data stream looks pretty good. Fuel trims are all +or- 5% and all sensors appear to be within range."
Luke
First of all, your boost should rise consistently, slow and steady as rpms rise. There should never be any dip in boost unless rpm dips. Based on your graph, this is not the case with your car. You have a boost leak which is further evident by looking at how the hp numbers temporarily flat line just above 6000 rpm. If your system is the standard VF system for a 99 C2, then the pulley used will generate 5.8 psi of boost. This is a mechanically generated boost and whether an engine is tuned properly or not will not change the boost. So where is the missing 0.8 psi?
It is IMPOSSIBLE for an otherwise unmodified 3.4 liter engine running 5 psi of boost and an a/f ratio of 10:1 to generate 344 rwhp. Therefore, either the hp numbers are wrong or the a/f sensor is wrong.
As far as your claim that dynos are a true measure of rwhp and are “always within 1-2hp”, then why the more than 2% (8 hp) difference in your dyno runs made 3 minutes apart?
Fuel trim has absolutely no effect on power generated at WOT. Nor does the fact that your O2 sensors maintain 14.5:1 a/f ratio in closed loop. Voltage reading from your O2 sensors at WOT near redline will more accurately tell you what your a/f ratio is.
First thing I would do is to have whoever did the install, redo it properly and eliminate your boost leak. Then record the MAF signal at WOT near redline along with O2 sensor voltage, timing graph and boost behind the throttle body.
First of all, your boost should rise consistently, slow and steady as rpms rise. There should never be any dip in boost unless rpm dips. Based on your graph, this is not the case with your car. You have a boost leak which is further evident by looking at how the hp numbers temporarily flat line just above 6000 rpm. If your system is the standard VF system for a 99 C2, then the pulley used will generate 5.8 psi of boost. This is a mechanically generated boost and whether an engine is tuned properly or not will not change the boost. So where is the missing 0.8 psi?
It is IMPOSSIBLE for an otherwise unmodified 3.4 liter engine running 5 psi of boost and an a/f ratio of 10:1 to generate 344 rwhp. Therefore, either the hp numbers are wrong or the a/f sensor is wrong.
As far as your claim that dynos are a true measure of rwhp and are “always within 1-2hp”, then why the more than 2% (8 hp) difference in your dyno runs made 3 minutes apart?
Fuel trim has absolutely no effect on power generated at WOT. Nor does the fact that your O2 sensors maintain 14.5:1 a/f ratio in closed loop. Voltage reading from your O2 sensors at WOT near redline will more accurately tell you what your a/f ratio is.
First thing I would do is to have whoever did the install, redo it properly and eliminate your boost leak. Then record the MAF signal at WOT near redline along with O2 sensor voltage, timing graph and boost behind the throttle body.
He did find a PARTIAL leak in the blow off valve, but it is getting 5.8-6lbs now after the blow off valve was tightened. And pressure tested the complete engine and it held pressure like it was supposed to with no leaks. However the air/furl is still a flat very rich 10.3 and a good 14.7ish partial throttle.
Hes installing a SAFC neo in the car and custom made a smaller pulley for me to run 8ish-lbs and lean the car out to the proper 11.5 a/f...should wake the car up quite a bit.
He did find a PARTIAL leak in the blow off valve, but it is getting 5.8-6lbs now after the blow off valve was tightened. And pressure tested the complete engine and it held pressure like it was supposed to with no leaks. However the air/furl is still a flat very rich 10.3 and a good 14.7ish partial throttle.
Hes installing a SAFC neo in the car and custom made a smaller pulley for me to run 8ish-lbs and lean the car out to the proper 11.5 a/f...should wake the car up quite a bit.
It was obvious that you had a leak and that is why you were running lean. There is no way that correcting the leak would not have substantially richened the engine out. Why do you believe this guy's dyno numbers or a/f ratio? Find another tuner that knows what he is doing. The dyno is wrong. Plain and simple.
As far as the SAFC neo, you can do the same thing it can for less than a dollar.
Last edited by 1999Porsche911; 10-29-2009 at 04:33 PM.
It was obvious that you had a leak and that is why you were running lean. There is no way that correcting the leak would not have substantially richened the engine out. Why do you believe this guy's dyno numbers or a/f ratio? Find another tuner that knows what he is doing. The dyno is wrong. Plain and simple.
As far as the SAFC neo, you can do the same thing it can for less than a dollar.
A boost leak would cause an engine to run rich, not lean...am i wrong?
Mind sharing your thoughts on this "dollar" tuning idea?
A boost leak would cause an engine to run rich, not lean...am i wrong?
Mind sharing your thoughts on this "dollar" tuning idea?
It would cause the engine to run rich because the computer thinks it is getting X amount of air and injects the fuel accordingly. Boost leak reduces the amount of air getting to the cylinders. That is why you were running so rich. In closed loop, it doesn't matter since the O2 sensors can correct for the leak, up to a point.
It would cause the engine to run rich because the computer thinks it is getting X amount of air and injects the fuel accordingly. Boost leak reduces the amount of air getting to the cylinders. In closed loop, it doesn't matter since the O2 sensors can correct for the leak, up to a point.
correct but I was there when they pressure tested it...not a single leak. It held 10psi steady on the gauge....
Well I'll let you know the result after the AFC neo goes in and I run 8-9lbs and fix that shi*ty tune up a lot
Last edited by brandongt3; 10-30-2009 at 12:07 PM.
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