Modifying timing/fuelling easily and effectively
11-19-2005, 03:30 PM
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Modifying timing/fuelling easily and effectively
Q: Is there a cheap way and easy way of retuning air/fuel ratio [and if necessary timing] of cars when changing the intake, exhaust, fueling or combustion point [eg: exhaust, headers, boost, better-flowing MAF, firestorm plugs, water injection, etc]?
A: Here's a couple of suggestions of how this could be done on a 928.
1/ If requiring a scientific approach to the tuning process, the narrow or wideband sensor output should ideally be logged against RPM using a analog data aquisition device like the cheap DataQ [$25/50US DI-194RS/DI-148U $50US] on Ebay.
A practical example of this is shown the URLS below:
http://cyberdave.org/CarTest.html
http://cyberdave.org/carwb.html
Shareware/freeware to be used with the DataQ device is available at
http://www.ultimaserial.com/
http://groups.yahoo.com/group/ultimaserial_group/
2/ A cheaper way is to do open-loop tuning while monitoring the O2 sensor signal. Disconnecting the o2 sensor so car goes into open loop tuning [no O2 sensor correction, just using MAF/throttle position,.etc], then monitor the o2 sensor signal with a digital voltmeter for appropriate air/fuel ratio (AFR) at various different throttle positions (eg: increments of 500rpm). Adjust the MAF signal using techniques presented below until appropriate AFR is obtained. With normal plugs this may be between 12:1 - 16:1 depending on desired fuel/economy or performance. 14.7:1 being the point of minimal exhaust gas emission.
A table of O2 sensor voltage to air/fuel ratio http://wbo2.com/sw/20-tables.xls. "Nbsim" is the O2 sensor output voltage for row for corresponding Lambda and AFR presented. The NBsim worksheet providing a at a glance representation.
3/ Modifying the the timing and fuel maps can be performed a number of different methods. Three are presented below:
[i] Cheapest/easiest way way would be adjust the timing via the distributor position and adjust the fuelling curve for O2 signal and MAF signal using:
* O2 signal, for constant cruise conditions: a free mixture controller schematic is available at http://better-mileage.com/memberadx.html which changes the stoich point of a narrowband O2 sensor. Combined with water injection the author of the website claims 18% improvement in fuel economy!!
* MAF signal, for changing throttle conditions: cheap Jaycar Digital Fuel Adjuster (DFA) or or more expensive Apexi SAFC-II device on Ebay. DFA is in my opinion better as it provides up to 128 points of adjustment between 0-5V as explained at http://autospeed.drive.com.au/cms/A_2418/article.html. Available as self-build kit at URLs below:
[US/Canada]
http://www.jaycarelectronics.com/pro...Max=&SUBCATID=
$51US
http://www.jaycarelectronics.com/pro...Max=&SUBCATID=
$38US
[AUS/NZ]
http://www.jaycar.com.au/productView...Max=&SUBCATID=
$80AUS
http://www.jaycar.com.au/productView...Max=&SUBCATID=
$60AUS
[ii] megasquirt internet/forum developed ECU in piggyback mode using software provided. The fuel maps responding to the O2 and MAF signal. The great thing is megasquirt can be later extended to provide the ultimate tuning device: FULL ecu control of the fueling and timing, use wideband sensor input to allow self-monitoring of an AFR and can use A MAP sensor instead of a MAF. All available at a later date if comfortable in doing so. Less than $500US built. See http://www.megasquirt.info
Other piggyback ECUs are available too. Motec, Haltech, Autronic, Wolf3D. A good price/performance point being the PerfectPower SMT6/SMT7 piggyback ECU.
[iii] shartuner to change existing eeprom ECU fuel maps. As per https://www.928gt.com/p-40359-928-sh...87-95-928.aspx
Pro: Cool idea, uses existing ECU, no wire cutting necessary
Con: bloody expensive ($1700), unless you loan out the equipment from someone. No idea of what the loan price is. Tuning limited to ECU capabilities designed a few decades ago.
Cheers,
sjsj
A: Here's a couple of suggestions of how this could be done on a 928.
1/ If requiring a scientific approach to the tuning process, the narrow or wideband sensor output should ideally be logged against RPM using a analog data aquisition device like the cheap DataQ [$25/50US DI-194RS/DI-148U $50US] on Ebay.
A practical example of this is shown the URLS below:
http://cyberdave.org/CarTest.html
http://cyberdave.org/carwb.html
Shareware/freeware to be used with the DataQ device is available at
http://www.ultimaserial.com/
http://groups.yahoo.com/group/ultimaserial_group/
2/ A cheaper way is to do open-loop tuning while monitoring the O2 sensor signal. Disconnecting the o2 sensor so car goes into open loop tuning [no O2 sensor correction, just using MAF/throttle position,.etc], then monitor the o2 sensor signal with a digital voltmeter for appropriate air/fuel ratio (AFR) at various different throttle positions (eg: increments of 500rpm). Adjust the MAF signal using techniques presented below until appropriate AFR is obtained. With normal plugs this may be between 12:1 - 16:1 depending on desired fuel/economy or performance. 14.7:1 being the point of minimal exhaust gas emission.
A table of O2 sensor voltage to air/fuel ratio http://wbo2.com/sw/20-tables.xls. "Nbsim" is the O2 sensor output voltage for row for corresponding Lambda and AFR presented. The NBsim worksheet providing a at a glance representation.
3/ Modifying the the timing and fuel maps can be performed a number of different methods. Three are presented below:
[i] Cheapest/easiest way way would be adjust the timing via the distributor position and adjust the fuelling curve for O2 signal and MAF signal using:
* O2 signal, for constant cruise conditions: a free mixture controller schematic is available at http://better-mileage.com/memberadx.html which changes the stoich point of a narrowband O2 sensor. Combined with water injection the author of the website claims 18% improvement in fuel economy!!
* MAF signal, for changing throttle conditions: cheap Jaycar Digital Fuel Adjuster (DFA) or or more expensive Apexi SAFC-II device on Ebay. DFA is in my opinion better as it provides up to 128 points of adjustment between 0-5V as explained at http://autospeed.drive.com.au/cms/A_2418/article.html. Available as self-build kit at URLs below:
[US/Canada]
http://www.jaycarelectronics.com/pro...Max=&SUBCATID=
$51US
http://www.jaycarelectronics.com/pro...Max=&SUBCATID=
$38US
[AUS/NZ]
http://www.jaycar.com.au/productView...Max=&SUBCATID=
$80AUS
http://www.jaycar.com.au/productView...Max=&SUBCATID=
$60AUS
[ii] megasquirt internet/forum developed ECU in piggyback mode using software provided. The fuel maps responding to the O2 and MAF signal. The great thing is megasquirt can be later extended to provide the ultimate tuning device: FULL ecu control of the fueling and timing, use wideband sensor input to allow self-monitoring of an AFR and can use A MAP sensor instead of a MAF. All available at a later date if comfortable in doing so. Less than $500US built. See http://www.megasquirt.info
Other piggyback ECUs are available too. Motec, Haltech, Autronic, Wolf3D. A good price/performance point being the PerfectPower SMT6/SMT7 piggyback ECU.
[iii] shartuner to change existing eeprom ECU fuel maps. As per https://www.928gt.com/p-40359-928-sh...87-95-928.aspx
Pro: Cool idea, uses existing ECU, no wire cutting necessary
Con: bloody expensive ($1700), unless you loan out the equipment from someone. No idea of what the loan price is. Tuning limited to ECU capabilities designed a few decades ago.
Cheers,
sjsj
11-19-2005, 06:27 PM
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Originally Posted by Sterling
Also, as far as I know sharktuner does not have ignition remapping capabilities.
i think that was next on the list for John to try actually.
.
11-19-2005, 09:16 PM
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Originally Posted by Sterling
... based on the premise described above it would be virtually impossible to modify the timing to its fullest potential without a dyno, much less for a program to do it.....
* DIY detonation detection using cheap electronics. Read the blurb at it: http://autospeed.drive.com.au/cms/A_2717/article.html
Cost of one of the electronic stethoscopes presented for detonation detection (as part of timing adjustment): $AUD10.50. Subscription cost alone to autospeed cost you less than 30 mins on a dyno.
NOTE: No affiliation with autospeed or providing info on toilet paper usage.
sjsj
11-19-2005, 10:07 PM
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Originally Posted by Sterling
.. adjusting air/fuel can be a DIY project ..
It's not rocket science. Benefits being better performance and better economy. Good coolant and synthetic oil being highly recommended in case engine runs temporarily leaner and therefore hotter during air fuel ratio experimentation.
If modifing timing, then consider electronic stethoscope. Available for as little as $10.50AUD. Autospeed recommended firstly in 1999 and subsequently revised in 2003. Autospeed mag being a great and respected resource for the DIY home tuner.
NOTE: Not affiliated with any oil, fuel, air, coolant, spark plug company or with your favorite toilet tissue manufacturer (eg: Crap-On).
sjsj
11-19-2005, 11:25 PM
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sjsj, you might want to pay attention to whom you are talking. Sterling is far from an idiot that you have to explain knock sensors or pinging. He built the only variable valve timing 928 which happens to be a custom stroker running Motec stand alone engine management. Read more of what people have done and are thinking of doing rather than advertising BS and cheesy car mag articles.
11-19-2005, 11:46 PM
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sjsj,
If you really want to modify your timing and fuel maps, the ONLY good way to do this is with a true standalone EMS. Period. And the only way to verify your 'tuning' is on a dyno, where loads on the motor can be held (speeds that would be unsafe to even try on the street while tuning).
SAFC's merely trick the stock computer and will wreak havoc with timing.
Messing with timing and fuel can result in a cleaner burning motor... more power, better fuel economy. However, going too far in any direction pushes you that much closer to BOOM! One bad tank of gas (or whatever) is all it takes.
And I'll second that Sterling knows what he's saying.
If you really want to modify your timing and fuel maps, the ONLY good way to do this is with a true standalone EMS. Period. And the only way to verify your 'tuning' is on a dyno, where loads on the motor can be held (speeds that would be unsafe to even try on the street while tuning).
SAFC's merely trick the stock computer and will wreak havoc with timing.
Messing with timing and fuel can result in a cleaner burning motor... more power, better fuel economy. However, going too far in any direction pushes you that much closer to BOOM! One bad tank of gas (or whatever) is all it takes.
And I'll second that Sterling knows what he's saying.
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11-20-2005, 12:30 AM
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Originally Posted by chris0626
sjsj,
If you really want to modify your timing and fuel maps, the ONLY good way to do this is with a true standalone EMS. Period. And the only way to verify your 'tuning' is on a dyno, where loads on the motor can be held (speeds that would be unsafe to even try on the street while tuning).
SAFC's merely trick the stock computer and will wreak havoc with timing.
Messing with timing and fuel can result in a cleaner burning motor... more power, better fuel economy. However, going too far in any direction pushes you that much closer to BOOM! One bad tank of gas (or whatever) is all it takes.
And I'll second that Sterling knows what he's saying.
If you really want to modify your timing and fuel maps, the ONLY good way to do this is with a true standalone EMS. Period. And the only way to verify your 'tuning' is on a dyno, where loads on the motor can be held (speeds that would be unsafe to even try on the street while tuning).
SAFC's merely trick the stock computer and will wreak havoc with timing.
Messing with timing and fuel can result in a cleaner burning motor... more power, better fuel economy. However, going too far in any direction pushes you that much closer to BOOM! One bad tank of gas (or whatever) is all it takes.
And I'll second that Sterling knows what he's saying.
Internet developed technology combining by the creative input of thousands.
* Tuning can be done without dyno and cheaply so, RE: Dataq, wideband.
Easiest is using the stock O2 narrowband sensor and voltmeter.
* SAFCs or DFA allow modification of the MAF signal input into the ECU that is evaluated to determine fuel injection levels. Timing signal is not modified at all.
* Go too far and allow the knock sensors to kick in, no boom necessary, other than the loss of breath you get from fearing the boom whenever you turn the key.
Disclaimer: I do not have shares in your favourite toilet paper manufacturing company (eg: Crap-On incorporated), or any others mentioned above.
sjsj
11-20-2005, 12:38 AM
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Originally Posted by FlyingDog
sjsj, you might want to pay attention to whom you are talking. Sterling is far from an idiot that you have to explain knock sensors or pinging. He built the only variable valve timing 928 which happens to be a custom stroker running Motec stand alone engine management. Read more of what people have done and are thinking of doing rather than advertising BS and cheesy car mag articles.
Truth is not bought by supposed credentials, sorry mate. Not on this side of part of the planet anyway.
11-20-2005, 01:15 AM
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Originally Posted by Sterling
the problem with your theory is this:
THe 928 factory computer only retard the timing 6 degrees...... its not variable as far as I know, so if you add 15 degrees of timing in any one place, then the computer can only take out 6 degrees, and you are still too far advanced 9 degrees...... if you are on boost and this in low load, and you don't correct this your pistons will suffer.
on a side note, since you appear to be new to this forum, most of us here know each other by name.... also being new, you may want to search the archives and see that there have been quite a few discussions about different technologies and the quest to apply them to the 928. There are alot of frauds out there on the internet, so you will have to understand our being skeptics. It also seems like every week there is some new expert (who usually doesn't even own a 928) signing in trying to educate the rest of us to what we need to do to improve the performance of our cars....
THe 928 factory computer only retard the timing 6 degrees...... its not variable as far as I know, so if you add 15 degrees of timing in any one place, then the computer can only take out 6 degrees, and you are still too far advanced 9 degrees...... if you are on boost and this in low load, and you don't correct this your pistons will suffer.
on a side note, since you appear to be new to this forum, most of us here know each other by name.... also being new, you may want to search the archives and see that there have been quite a few discussions about different technologies and the quest to apply them to the 928. There are alot of frauds out there on the internet, so you will have to understand our being skeptics. It also seems like every week there is some new expert (who usually doesn't even own a 928) signing in trying to educate the rest of us to what we need to do to improve the performance of our cars....
It is obviously a great source of information for Porsche owners and of course I wouldn't want to shake up the status quo by any means.
sjsj
11-20-2005, 01:37 AM
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We're just saying read up a bit before jumping in. There is a new member guide (I think it's tacked at the top of the forum). When you think something would apply to a 928, search first. If it's some overhyped crap like new spark plugs, think first. If it's too good to be true, it probably is...
11-20-2005, 01:58 AM
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Originally Posted by FlyingDog
We're just saying read up a bit before jumping in. There is a new member guide (I think it's tacked at the top of the forum). When you think something would apply to a 928, search first. If it's some overhyped crap like new spark plugs, think first. If it's too good to be true, it probably is...
sjsj
11-20-2005, 02:11 AM
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Of course! Just realize that a lot more people here can see through the hype either from experience with 928s or from experience with engineering/marketing/cars in general.
Just do more research first. You're asking beginner questions and backing them up with advertising hype... most of which is BS. You have to reallize that a 928 is not powered by a Chevy or Ford small block. The owners are not masses of Chevy or Ford buying idiots. If you take all of the Z06 Vettes and SCed Cobra Mustangs sold, weed out the posers, and stretch the remainder over 18 years of different variations you have us... without all of the money/engineering/experience... trying to figure out what we can co-opt from the Chevy and Ford crowd and what we have to do on our own. Unlike the ricer, Chevy and Ford scenes; our developement is not driven by hype. It is driven by hardcore carnuts and engineering geeks.
I am just a beginner. I know my place in the hierarchy. I try to learn from Sterling, Louis Ott, Andy Keel, Tim Murphy, John Kuhn, David Roberts, Jim Bailey, Mark Anderson, Marc Thomas, and on and on... and I interject my ideas here and there. A similar approach may work for you.
BTW, What did you buy? You said you have keys and no car...
Just do more research first. You're asking beginner questions and backing them up with advertising hype... most of which is BS. You have to reallize that a 928 is not powered by a Chevy or Ford small block. The owners are not masses of Chevy or Ford buying idiots. If you take all of the Z06 Vettes and SCed Cobra Mustangs sold, weed out the posers, and stretch the remainder over 18 years of different variations you have us... without all of the money/engineering/experience... trying to figure out what we can co-opt from the Chevy and Ford crowd and what we have to do on our own. Unlike the ricer, Chevy and Ford scenes; our developement is not driven by hype. It is driven by hardcore carnuts and engineering geeks.
I am just a beginner. I know my place in the hierarchy. I try to learn from Sterling, Louis Ott, Andy Keel, Tim Murphy, John Kuhn, David Roberts, Jim Bailey, Mark Anderson, Marc Thomas, and on and on... and I interject my ideas here and there. A similar approach may work for you.
BTW, What did you buy? You said you have keys and no car...
11-20-2005, 02:16 AM
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Originally Posted by FlyingDog
Just do more research first. You're asking beginner questions and backing them up with advertising hype... most of which is BS. ...
It is driven by hardcore carnuts and engineering geeks.
It is driven by hardcore carnuts and engineering geeks.
If new ideas are not welcome here, then please draw the line in the sand right now and I shall find other forums for such discussion. It may help to answer the question, raised for a third time now:
"are new forum members with new ideas welcome here?!" Sidelining the question doesn't help clarify it.
sjsj
11-20-2005, 02:41 AM
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Originally Posted by Sterling
new members with new ideas are most certainly welcome. however you will find that the 928 group base most of their trust in new ideas by seeing or hearing 1st hand about improvements, usually backed up by dyno data... (imperical data) I would also have to add that most 928 owners are interested in improving performance, but are skeptical of all the "vapor-ware" out there. Lets face it for every single verifiable fact found online, there are thousands of hoaxes/misinformation.
Perhaps you would like to answer the question then, because I am still a bit confused by all these rules and regulations and some hierachy of knowledge in place that I cannot see, or was ever informed of in the beginning when I signed up for this forum (ie: terms and conditions).
So for me the fundamental question for my existence in existence in partaking in this forum, without censorship or undue criticism remains the answering of the following:
"are new members with new ideas welcome here"
BTW, this is all