Supercharger Issue VF-Engineering
05-06-2016, 12:01 PM
#1
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Supercharger Issue VF-Engineering
I have a 2006, 3.6 Carrera 4, manual transmission with the VF-Engineering supercharger kit. It has been installed in the car since 2013 and about 30K miles and for the last 10K or so I've been fighting a problem which has had the car back to the local dealership too many times to count.
There is some kind of issue between the Mass Airflow Sensor relating
to the supercharger and the tune programming on the ECU. If I accelerate hard thru first gear the car performance when cold the acceleration is flawless, 2nd gear 6 and 7000 rpm's the car surges and
dips in RPM and Surges but not steady as it should.
If the mass airflow sensor is disconnected and the ecu goes into closed loop then it runs perfect in each gear. We have tried replacing the MAF and the associated temp sensor on the supercharger intercooler but no cure. Also, replaced all of the sparkplugs.
The problem is much more pronounced when the car is warm and also when the air temp outside is hotter than 70 degrees which is most of the time since I live in Florida.
I have called VF multiple times and they always say to send an email which I've done multiple times and VF-engineering never puts me thru to a tech.. The Dealer has run into the same problem So anyone that can offer some assistance with this issue would be greatly appreciated as I have the car at the dealership now trying to chase down the problem again.
Thanks.
There is some kind of issue between the Mass Airflow Sensor relating
to the supercharger and the tune programming on the ECU. If I accelerate hard thru first gear the car performance when cold the acceleration is flawless, 2nd gear 6 and 7000 rpm's the car surges and
dips in RPM and Surges but not steady as it should.
If the mass airflow sensor is disconnected and the ecu goes into closed loop then it runs perfect in each gear. We have tried replacing the MAF and the associated temp sensor on the supercharger intercooler but no cure. Also, replaced all of the sparkplugs.
The problem is much more pronounced when the car is warm and also when the air temp outside is hotter than 70 degrees which is most of the time since I live in Florida.
I have called VF multiple times and they always say to send an email which I've done multiple times and VF-engineering never puts me thru to a tech.. The Dealer has run into the same problem So anyone that can offer some assistance with this issue would be greatly appreciated as I have the car at the dealership now trying to chase down the problem again.
Thanks.
05-06-2016, 01:34 PM
#2
Three Wheelin'
It sounds like something is warming and expanding, and thus a leak is introduced. The leak is causing the ECU to change settings as the leak/pressure is variable, so you get the comp making constant adjustments. Surging would be normal. Or, the leak is causing boost to drop as pressure is escaping.
In loop mode, where no thinking is going on, I would guess it runs okay (but you're risking reliability if you put it under hard load/accel), but it's probably down on total power, or would be, if you tried to get on it hard.
It's hard to pinpoint, but there is a leak somewhere. When things warm, something is expanding ans introducing the leak/loss of pressure.
This is high level... of course.
It is concerning when a vendor can't be responsive.
In loop mode, where no thinking is going on, I would guess it runs okay (but you're risking reliability if you put it under hard load/accel), but it's probably down on total power, or would be, if you tried to get on it hard.
It's hard to pinpoint, but there is a leak somewhere. When things warm, something is expanding ans introducing the leak/loss of pressure.
This is high level... of course.
It is concerning when a vendor can't be responsive.
05-06-2016, 01:42 PM
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Supercharger Issue VF-Engineering
Philster,
Thanks for the reply. The dealer has checked for boost leaks and there aren't any. They have hooked up to a computer and drove it at the same time being hooked up and taken all different readings at all rpms and they are convinced the problem is with the Tune on the ECU after it hits peak torque at between 6000 and 6500 that it's a combination of fuel/spark being cut. Kind of like what happens when you hit the rev limiter but, not so extreme. Unfortunately we can't get to speak with anyone at VF.
John
Thanks for the reply. The dealer has checked for boost leaks and there aren't any. They have hooked up to a computer and drove it at the same time being hooked up and taken all different readings at all rpms and they are convinced the problem is with the Tune on the ECU after it hits peak torque at between 6000 and 6500 that it's a combination of fuel/spark being cut. Kind of like what happens when you hit the rev limiter but, not so extreme. Unfortunately we can't get to speak with anyone at VF.
John
05-07-2016, 09:59 AM
#4
RL Community Team
Rennlist Member
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As crazy as it sounds, these engines rely a lot on the temp readings from the coolant temp sensor. Since you're seeing a difference between hot and cold temp operation, try changing that, or running live values on Durametric tracking the readings from intake air temp, RPM & coolant temp and see if there's an anomaly in the readings around where the issue occurs.
In a forced induction car, the intake air temp has to be taken at the intake manifold after the air is compressed, since compressing it generates heat, rather than using the temp sensor in the MAF. In my RUF supercharged car, there's a temp sensor threaded into the right side intake manifold and the wires from that are spliced into the wiring harness that goes from the MAF to the car (DME). I had an issue with one of the solder joints intermittently losing contact and causing a similar type of result, but it was at my low-end, not the top end. Trace the wiring that relates to the temp sensor and MAF to make sure you don't have an issue there somewhere.
Lastly, my car uses a non-standard MAF forward some reason, it's from something like a Fiat and impossible to find over here. Make sure the new MAF that was installed has the same Bosch part # that was in your car when it was running correctly. Changing the MAF as a diagnostic measure, and installing potentially the wrong one, would have you chasing your tail forever.
Good luck.
In a forced induction car, the intake air temp has to be taken at the intake manifold after the air is compressed, since compressing it generates heat, rather than using the temp sensor in the MAF. In my RUF supercharged car, there's a temp sensor threaded into the right side intake manifold and the wires from that are spliced into the wiring harness that goes from the MAF to the car (DME). I had an issue with one of the solder joints intermittently losing contact and causing a similar type of result, but it was at my low-end, not the top end. Trace the wiring that relates to the temp sensor and MAF to make sure you don't have an issue there somewhere.
Lastly, my car uses a non-standard MAF forward some reason, it's from something like a Fiat and impossible to find over here. Make sure the new MAF that was installed has the same Bosch part # that was in your car when it was running correctly. Changing the MAF as a diagnostic measure, and installing potentially the wrong one, would have you chasing your tail forever.
Good luck.
05-08-2016, 04:56 PM
#5
Rennlist Member
Six months back, I bought an 08 CS with a TPC turbo kit and have since done a lot of work to get it running perfectly. I'm not a mechanic, just an enthusiast, so take my suggestions with a grain of salt, but I did a lot of research and first-hand troubleshooting on my car which helped sharpen my sense of how these engines work (including with boost) .
The steps below work for most cars, but are particularly relevant for diagnosing forced induction engines as they are more sensitive to anything being out of spec.
From what you've described, it sounds like you're either having some detonation which is pulling timing and power, or you've got a sensor (or two) that needs replacing - - MAF and 02s are most likely.
Good news:
1) If your car once ran OK (when the supercharger install was newer) in identical weather and driving conditions, the issue is not likely your tune, but a sensor or other component that's changed on your engine.
2) That your car runs better when open loop (MAF unplugged) also suggests a sensor or other problem, not a base tune problem. Also, this would seem to rule out other fueling and ignition issues (like clogged fuel filter, failing fuel pump, or failing coils/plugs).
Caution:
3) Pulling power under high RPM load when hot sounds like it could be detonation, which is dangerous to your engine. Put some unleaded race gas or octane booster (available on Amazon) in your tank and see if that improves running - - if yes, you could be having a detonation issue. No need to fill the whole tank, but run your existing tank low before filling for most impact.
Also add Techron fuel system cleaner to the next 3 tanks and see if that helps. Techron will help clean deposits that may be making hot spots that contribute to detonation. Note that forced induction engines are often tuned to run rich which can contribute to extra deposits (and reduced life for O2 sensors - - see below). Techron genuinely helps clean a deposits which cause running issues. It made a noticeable difference for me.
Troubleshooting (generally in order of decreasing usefulness per dollar spent):
4) Post your question on the 996/997 Turbo forums. There are more members that have experience with boosted engines and troubleshooting running issues (and especially detonation) and may have additional thoughts.
5) Do you have Durametric? It's the best tool for logging what the engine is doing although a cheap OBD scanner can help for less money. You can learn a lot by logging the following: engine load, rpm, timing, lambda (or primary O2 readings), and Short Term and Long Term fuel trims for both banks. These are the key readings, and you can do theses with a cheap OBD2 adapter and the Torque app, but the sample rate on the generic adapters is low - - only ~1 reading of all the above per second (you really want more resolution, although some is better than none) . Durametric records more per second and you can also log more things including misfires. Ideally, you'll see ST and LT fuel trims under +/- 10 (closer to zero is better). In particular, if LT trims are materially out of whack (> +/-10), you need to find whats causing that first - - probably an air leak, MAF, or O2 sensor issue.
Under high engine loads and RPM, lambda should be meaningfully less than 1 (and hopefully close to . 85). That would indicate a nice, safe rich mixture for full boost. Lambda below .75 is likely too rich and suggests other issues. Note that while cruising and under moderate load, lambda should otherwise be right around 1, maybe +/- .03, except when coasting from high RPM, during which time the computer cuts fuel and lambda spikes to 2 (very lean).
My experience suggests that timing varies a lot depending on a number of factors including rpm, load, and even whether you depress the clutch. What you want to check for is what the timing is doing when you experience your issues. At 6000+ rpm and high load, I'd expect to see timing advance of at least 12 degrees (more is better and indicates a happy engine at that speed). Less advance (or even retard) would suggest that you're having detonation issues and the computer is pulling timing to lower cylinder pressures and temps in an attempt to avoid damage. Durametric has better resolution for measuring timing under these conditions. In any case, even generic OBD2 logs can really help diagnose this.
6) Fix any intake leaks. It sounds like you tested for boost leaks, but also make sure there are no leaks anywhere on the intake all the way from the MAF to the engine. One other thought: Did you change the intake piping or filter? Note that MAFs can be affected by turbulence in the intake just before the MAF - - they are only accurate with smooth air flow. This is likely a moot point if the intake is original to the supercharger kit.
7) Make sure you've got the right MAF sensor, and make sure it's the real Bosch or Porsche sensor. If it's not one of those, it's immediately suspect. Denso claims to make one that's compatible with the Bosch (and is cheaper), but in my experience, it was not even close to being a substitute. Some are listed as remanufactured - - you don't want that either. Real deal only. I'm all in favor of finding cheaper (quality) substitutes, but this is not one part I was successful with alternatives. A new and correct MAF made a big difference on my car. To quote Mike Levitas regarding running issues on the TPC turbo: "it's always the MAF." Also, don't use an oiled air filter on the intake - - the oil from the filters kills MAFs. Use a paper or dry filter like an AEM.
8) Wideband / primary O2 sensors. With age, or other running issues (like a bad MAF or AOS), the O2 sensors get contaminated and lazy, even though they appear to be working when logged. The Bosch replacements are relatively cheap on Amazon (blue wire version) and made a meaningful difference on my car. You can save money by buying one sensor and seeing what impact it has on your fuel trims for that cylinder bank. If it moves them closer to zero trim (particularly relative to the other bank), you may have found part of your issue. O2s are easy to swap. This made a noticeable improvement on my car.
9) Replace your plugs and inspect / replace your coils. You mentioned that the plugs were done. Were the coils checked? They crack with heat and age and can cause random misfires (including heat or moisture related misfires). That your car runs fine when the MAF is unplugged suggests this is probably not your issue.
10) Pull your throttle body and check for oil in the intake. Drier is better, but I think a very light (greasy) covering is normal. Wet oil is bad. Oil reduces octane and would contribute to detonation. Any found oil could be coming from a failing AOS which is not uncommon at your mileage. There are other ways to test for a failing AOS by measuring crankcase vacuum through the oil filler cap - - Search is your friend.
Note that our aftermarket cars have can't/don't run the factory AOS exactly as designed (due to occasional manifold boost versus all time vacuum as designed). Instead the AOS may instead be vented to a catch can, intake (pre S/C or turbo), or to the exhaust. Of those methods, the latter is most effective, and the former methods can create issues over time (I have no clue how VF handles this) - - TPC vents to the intake which is not great due to not enough vacuum for the AOS/crankcase. I designed another solution using the AOS check valve from a Cayenne Turbo that restores the factory function as intended - - that's worthy of its own separate post.
11) Petza makes some good points regarding intake air temp (IAT) and water temp. I don't know whether your VF has a separate IAT sensor as does his Ruf kit, but the TPC kit uses the IAT sensor that's integrated into the MAF. So a bad sensor is unlikely to be your issue if yours is in the MAF, but that's easy to check with a scanner.
More importantly, as Petza points out, air temps go up with boost. And hotter intake air increases the risk of detonation. You mention that you have an intercooler (IC) - - that's good, as it should pull temps back down. But you need to make sure its working. For example, if it's a liquid IC, make sure system is filled and the coolant pump for the IC is working, else your IC won't be cooling the intake charge after the engine warms up. And make sure your front radiators are clear of debris that might be blocking cooling. Same applies to air to air ICs - - make sure nothing is blocking the flow of air.
As Petza points out, you ideally want to read the temp of your intake air at the intake manifold (and after the supercharger, turbo and/or IC). You may have to resort to installing an extra IAT sensor or thermocouple on the throttle body or manifold so that you can troubleshoot. But hopefully some of the above suggestions will resolve your issue before resorting to such.
I hope you or our other forced induction brethren find this useful. These cars have their own peculiarities that can be a bit trickier for the dealer to troubleshoot, but a good independent mechanic with forced induction knowledge should have no problem. The Audi, Mazda and turbo Miata forums actually do a great job covering these topics, but you have to search.
Good luck and best wishes.
The steps below work for most cars, but are particularly relevant for diagnosing forced induction engines as they are more sensitive to anything being out of spec.
From what you've described, it sounds like you're either having some detonation which is pulling timing and power, or you've got a sensor (or two) that needs replacing - - MAF and 02s are most likely.
Good news:
1) If your car once ran OK (when the supercharger install was newer) in identical weather and driving conditions, the issue is not likely your tune, but a sensor or other component that's changed on your engine.
2) That your car runs better when open loop (MAF unplugged) also suggests a sensor or other problem, not a base tune problem. Also, this would seem to rule out other fueling and ignition issues (like clogged fuel filter, failing fuel pump, or failing coils/plugs).
Caution:
3) Pulling power under high RPM load when hot sounds like it could be detonation, which is dangerous to your engine. Put some unleaded race gas or octane booster (available on Amazon) in your tank and see if that improves running - - if yes, you could be having a detonation issue. No need to fill the whole tank, but run your existing tank low before filling for most impact.
Also add Techron fuel system cleaner to the next 3 tanks and see if that helps. Techron will help clean deposits that may be making hot spots that contribute to detonation. Note that forced induction engines are often tuned to run rich which can contribute to extra deposits (and reduced life for O2 sensors - - see below). Techron genuinely helps clean a deposits which cause running issues. It made a noticeable difference for me.
Troubleshooting (generally in order of decreasing usefulness per dollar spent):
4) Post your question on the 996/997 Turbo forums. There are more members that have experience with boosted engines and troubleshooting running issues (and especially detonation) and may have additional thoughts.
5) Do you have Durametric? It's the best tool for logging what the engine is doing although a cheap OBD scanner can help for less money. You can learn a lot by logging the following: engine load, rpm, timing, lambda (or primary O2 readings), and Short Term and Long Term fuel trims for both banks. These are the key readings, and you can do theses with a cheap OBD2 adapter and the Torque app, but the sample rate on the generic adapters is low - - only ~1 reading of all the above per second (you really want more resolution, although some is better than none) . Durametric records more per second and you can also log more things including misfires. Ideally, you'll see ST and LT fuel trims under +/- 10 (closer to zero is better). In particular, if LT trims are materially out of whack (> +/-10), you need to find whats causing that first - - probably an air leak, MAF, or O2 sensor issue.
Under high engine loads and RPM, lambda should be meaningfully less than 1 (and hopefully close to . 85). That would indicate a nice, safe rich mixture for full boost. Lambda below .75 is likely too rich and suggests other issues. Note that while cruising and under moderate load, lambda should otherwise be right around 1, maybe +/- .03, except when coasting from high RPM, during which time the computer cuts fuel and lambda spikes to 2 (very lean).
My experience suggests that timing varies a lot depending on a number of factors including rpm, load, and even whether you depress the clutch. What you want to check for is what the timing is doing when you experience your issues. At 6000+ rpm and high load, I'd expect to see timing advance of at least 12 degrees (more is better and indicates a happy engine at that speed). Less advance (or even retard) would suggest that you're having detonation issues and the computer is pulling timing to lower cylinder pressures and temps in an attempt to avoid damage. Durametric has better resolution for measuring timing under these conditions. In any case, even generic OBD2 logs can really help diagnose this.
6) Fix any intake leaks. It sounds like you tested for boost leaks, but also make sure there are no leaks anywhere on the intake all the way from the MAF to the engine. One other thought: Did you change the intake piping or filter? Note that MAFs can be affected by turbulence in the intake just before the MAF - - they are only accurate with smooth air flow. This is likely a moot point if the intake is original to the supercharger kit.
7) Make sure you've got the right MAF sensor, and make sure it's the real Bosch or Porsche sensor. If it's not one of those, it's immediately suspect. Denso claims to make one that's compatible with the Bosch (and is cheaper), but in my experience, it was not even close to being a substitute. Some are listed as remanufactured - - you don't want that either. Real deal only. I'm all in favor of finding cheaper (quality) substitutes, but this is not one part I was successful with alternatives. A new and correct MAF made a big difference on my car. To quote Mike Levitas regarding running issues on the TPC turbo: "it's always the MAF." Also, don't use an oiled air filter on the intake - - the oil from the filters kills MAFs. Use a paper or dry filter like an AEM.
8) Wideband / primary O2 sensors. With age, or other running issues (like a bad MAF or AOS), the O2 sensors get contaminated and lazy, even though they appear to be working when logged. The Bosch replacements are relatively cheap on Amazon (blue wire version) and made a meaningful difference on my car. You can save money by buying one sensor and seeing what impact it has on your fuel trims for that cylinder bank. If it moves them closer to zero trim (particularly relative to the other bank), you may have found part of your issue. O2s are easy to swap. This made a noticeable improvement on my car.
9) Replace your plugs and inspect / replace your coils. You mentioned that the plugs were done. Were the coils checked? They crack with heat and age and can cause random misfires (including heat or moisture related misfires). That your car runs fine when the MAF is unplugged suggests this is probably not your issue.
10) Pull your throttle body and check for oil in the intake. Drier is better, but I think a very light (greasy) covering is normal. Wet oil is bad. Oil reduces octane and would contribute to detonation. Any found oil could be coming from a failing AOS which is not uncommon at your mileage. There are other ways to test for a failing AOS by measuring crankcase vacuum through the oil filler cap - - Search is your friend.
Note that our aftermarket cars have can't/don't run the factory AOS exactly as designed (due to occasional manifold boost versus all time vacuum as designed). Instead the AOS may instead be vented to a catch can, intake (pre S/C or turbo), or to the exhaust. Of those methods, the latter is most effective, and the former methods can create issues over time (I have no clue how VF handles this) - - TPC vents to the intake which is not great due to not enough vacuum for the AOS/crankcase. I designed another solution using the AOS check valve from a Cayenne Turbo that restores the factory function as intended - - that's worthy of its own separate post.
11) Petza makes some good points regarding intake air temp (IAT) and water temp. I don't know whether your VF has a separate IAT sensor as does his Ruf kit, but the TPC kit uses the IAT sensor that's integrated into the MAF. So a bad sensor is unlikely to be your issue if yours is in the MAF, but that's easy to check with a scanner.
More importantly, as Petza points out, air temps go up with boost. And hotter intake air increases the risk of detonation. You mention that you have an intercooler (IC) - - that's good, as it should pull temps back down. But you need to make sure its working. For example, if it's a liquid IC, make sure system is filled and the coolant pump for the IC is working, else your IC won't be cooling the intake charge after the engine warms up. And make sure your front radiators are clear of debris that might be blocking cooling. Same applies to air to air ICs - - make sure nothing is blocking the flow of air.
As Petza points out, you ideally want to read the temp of your intake air at the intake manifold (and after the supercharger, turbo and/or IC). You may have to resort to installing an extra IAT sensor or thermocouple on the throttle body or manifold so that you can troubleshoot. But hopefully some of the above suggestions will resolve your issue before resorting to such.
I hope you or our other forced induction brethren find this useful. These cars have their own peculiarities that can be a bit trickier for the dealer to troubleshoot, but a good independent mechanic with forced induction knowledge should have no problem. The Audi, Mazda and turbo Miata forums actually do a great job covering these topics, but you have to search.
Good luck and best wishes.
05-08-2016, 08:45 PM
#6
Instructor
This is really unfortunate that the vendor (VF) is more or less ignoring you. Especially since you would think that they could save you a lot of money and many hours due to their experience and expertise in the matter.
I've thought about going FI, but I've personally never been able to get TPC to even respond to my inquiries. Also, I've read more than one story about a customer not getting support after installation.
They charge quite a bit of a markup for their kits, compared to similar kits for non luxury cars.
I've thought about going FI, but I've personally never been able to get TPC to even respond to my inquiries. Also, I've read more than one story about a customer not getting support after installation.
They charge quite a bit of a markup for their kits, compared to similar kits for non luxury cars.
05-09-2016, 04:34 PM
#7
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Supercharger Issue VF-Engineering
Thanks for the replys. I've checked pretty much everything on the lists. The MAF was installed by the Porsche dealer and it is OEM. The coils were checked when the plugs were changed. The 4 O2 Sensors were checked by disconnecting and it made no difference when they were disconnected. The boost has been checked and it is getting the proper boost and no leaks have been detected. The temp sensor located in the supercharger intercooler was changed when the MAF was and has been checked and is functioning fine. The dealer still suspects the problem is with the tune but, we still can't get a response from VF. So, the dealer has contacted GIAC since they have a person there that they deal with to see if they will upload the tune and see if anything is wrong with that. That's is the status as of today and meanwhile the car sits at the dealership.
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05-09-2016, 04:51 PM
#8
RL Community Team
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Thanks for the replys. I've checked pretty much everything on the lists. The MAF was installed by the Porsche dealer and it is OEM. The coils were checked when the plugs were changed. The 4 O2 Sensors were checked by disconnecting and it made no difference when they were disconnected. The boost has been checked and it is getting the proper boost and no leaks have been detected. The temp sensor located in the supercharger intercooler was changed when the MAF was and has been checked and is functioning fine. The dealer still suspects the problem is with the tune but, we still can't get a response from VF. So, the dealer has contacted GIAC since they have a person there that they deal with to see if they will upload the tune and see if anything is wrong with that. That's is the status as of today and meanwhile the car sits at the dealership.
- Was the new MAF they installed at the dealer the same part # as the one that was removed, or in other words, do you know that the MAF that was originally installed when the car was running right was an OEM Standard MAF as it could have been a different Bosch MAF? That probably won't help you much since that MAF was probably discarded when the new one was installed, but maybe they gave it to you and you still have it where you can look.
- What about the coolant temperature sensor? I don't see that you mentioned anything about that one being tested or replaced.
05-09-2016, 05:24 PM
#9
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Supercharger Issue VF-Engineering
Based on your note - 2 questions:
Was the new MAF they installed at the dealer the same part # as the one that was removed, or in other words, do you know that the MAF that was originally installed when the car was running right was an OEM Standard MAF as it could have been a different Bosch MAF? That probably won't help you much since that MAF was probably discarded when the new one was installed, but maybe they gave it to you and you still have it where you can look.
They did pitch the old one but, I just hung up the phone with the dealer and they confirmed it was the same partnumber.
What about the coolant temperature sensor? I don't see that you mentioned anything about that one being tested or replaced.
The replacement temp sensor was purchased from VF. Their sales department seems to answer the phone, only tech support doesn't.
Was the new MAF they installed at the dealer the same part # as the one that was removed, or in other words, do you know that the MAF that was originally installed when the car was running right was an OEM Standard MAF as it could have been a different Bosch MAF? That probably won't help you much since that MAF was probably discarded when the new one was installed, but maybe they gave it to you and you still have it where you can look.
They did pitch the old one but, I just hung up the phone with the dealer and they confirmed it was the same partnumber.
What about the coolant temperature sensor? I don't see that you mentioned anything about that one being tested or replaced.
The replacement temp sensor was purchased from VF. Their sales department seems to answer the phone, only tech support doesn't.
05-09-2016, 06:01 PM
#10
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Also, if disconnecting the O2 sensors makes now difference, might that not mean that the O2 sensors are bad and not doing their jobs?
05-10-2016, 11:18 AM
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Supercharger Issue VF-Engineering
Hi all,
Thanks for the replys. I finally got a return phone call to the dealership by VF-Engineering and an email to me.
It seems that the problem here is that at high RPM with boost the MAF is out of range. VF-Engineering's answer to that is to put a resister in line on the signal wire to the MAF to give lower numbers back to the DME or as an alternate adjust the software to scale down the MAF. The problem of course is that we will have to confirm that the AFR is not too lean and not safe.
Basically this is a BS fix. Rather than replacing the MAF with a MAP sensor and properly tuning to the MAP they know there is an issue here and their fix is to give false readings from the MAF across the entire RPM range to smooth out the high end.
Anyone know a good tuner in east central florida ?
Thanks for the replys. I finally got a return phone call to the dealership by VF-Engineering and an email to me.
It seems that the problem here is that at high RPM with boost the MAF is out of range. VF-Engineering's answer to that is to put a resister in line on the signal wire to the MAF to give lower numbers back to the DME or as an alternate adjust the software to scale down the MAF. The problem of course is that we will have to confirm that the AFR is not too lean and not safe.
Basically this is a BS fix. Rather than replacing the MAF with a MAP sensor and properly tuning to the MAP they know there is an issue here and their fix is to give false readings from the MAF across the entire RPM range to smooth out the high end.
Anyone know a good tuner in east central florida ?
05-10-2016, 11:52 AM
#13
Hi all,
Thanks for the replys. I finally got a return phone call to the dealership by VF-Engineering and an email to me.
It seems that the problem here is that at high RPM with boost the MAF is out of range. VF-Engineering's answer to that is to put a resister in line on the signal wire to the MAF to give lower numbers back to the DME or as an alternate adjust the software to scale down the MAF. The problem of course is that we will have to confirm that the AFR is not too lean and not safe.
Basically this is a BS fix. Rather than replacing the MAF with a MAP sensor and properly tuning to the MAP they know there is an issue here and their fix is to give false readings from the MAF across the entire RPM range to smooth out the high end.
Anyone know a good tuner in east central florida ?
Thanks for the replys. I finally got a return phone call to the dealership by VF-Engineering and an email to me.
It seems that the problem here is that at high RPM with boost the MAF is out of range. VF-Engineering's answer to that is to put a resister in line on the signal wire to the MAF to give lower numbers back to the DME or as an alternate adjust the software to scale down the MAF. The problem of course is that we will have to confirm that the AFR is not too lean and not safe.
Basically this is a BS fix. Rather than replacing the MAF with a MAP sensor and properly tuning to the MAP they know there is an issue here and their fix is to give false readings from the MAF across the entire RPM range to smooth out the high end.
Anyone know a good tuner in east central florida ?
05-10-2016, 11:04 PM
#14
Rennlist Member
Well, it's good you have your answer at least. It seems odd that the kit would have shipped without an appropriately sized MAF and/or tune to work that way.
Did it always have those running issues (since SC install)? Seems like it must have (or at least been on the ragged edge of the MAF range when new).
Let us know if the resistor fixes the issue, or whether it needs an ECU reflash.
Did it always have those running issues (since SC install)? Seems like it must have (or at least been on the ragged edge of the MAF range when new).
Let us know if the resistor fixes the issue, or whether it needs an ECU reflash.
05-11-2016, 08:12 PM
#15
RL Community Team
Rennlist Member
Rennlist Member
There's a guy at my Raby M96-102 class this week with a VF setup like you. He says if it didn't always exhibit this behavior that you have an air leak somewhere, most likely vacuum, and it can be tiny and almost impossible to find, like a hose or clamp that's just angled or off by a little and it will cause what you're seeing. Just passing along what he told me today.