Oops - I filled up with regular (87 octane gas) - will it hurt the car

[KevinMac]

So let me get this straight you are comparing a Mazda CX 7 a passenger crossover vehicle vs a performance car, wow! We are talking Porsche a performace vehicle!. Once again would you really put 87 octane in Carrera turbo "street engine"?

If the tank is empty, and only regular is available, yes, absolutely YES..!!

Well if you don't know what a performane tune is, which there are many avialable for Porsche, how can you comment on the acceptable fuels to use?

NO comment.

Oh btw if I remember correctly most European countries have a minimum or "regular"@ 95 RON which is = to 91 in the US. Kinda matches the octane recommendatin in the owners manual 91 to 93!

Funny how that works out!

Yes, LOL, it is funny, truly FUNNY..

"to provide optimum performance and fuel economy Porsche recommends unleaded premium fuel with an octane rating of 98 RON (93 CLC or AKI)."

"be assured that your vehicle will operate properly with octane numbers of at least 95 RON (90 CLC or AKI)....

So, by your "standards" when we in the US fuel with premium we're really using "regular" as defined by Porsche..??

Would that mean their premium is ~100 octane....??

With that said, all I am saying is I would not make any speculation on using 87 unless Porsche says it's okay, or someone has looked at the maps! To just randomly say you can use it is nothing but speculation.

Check this out from PCA - looks like what I have been saying.

http://www.pca.org/tech/tech_qa_question.a...9-50218293CFDC}

wwest - think you just like to argue for the sake of an arguement.

Your the one that posted low octane in Europe. As I posted their low octane is = to 91 in the US = within spec of the porsche spec! So what's your point!

Point me to where does Porsche says regular, all my documents including the maintenance manual says Ron 98 = 93 Ron+Mon.

That's what's funny you are all over the place with your comments!

Low octane 87 in a twin turbo, that answers it all. Thanks for such a competant answer! Now I know where your knowledge really lies! Your true colors are really showing now! Nice job!

Edited August 12, 2008 by KevinMac

[wwest]

Whatever....

[wdonovan]

I bow to the self proclaimed experts who know nothing about the mapping software and insist that the scanner watching the sensors tell the combustion profiles! No longer worth the discussion! Do what you like it's your vehicle!

Such a stubborn, condescending view begs for other opinions. Here's my 2 cents. It doesn't take a "self proclaimed expert" to know that there is fuel in the tank without using a dipstick. The expert can monitor the fuel level gauge and if there is no reason to disbelieve the gauge, he can tell the level from it.

Much in the same way, a "self proclaimed expert" can monitor the "combustion profiles" (boy there's a twenty dollar phrase) by monitoring knock sensors and ignition timing "profiles". The knock sensor feedback is quite simply a monitor of "There is detonation" or "There is no detonation". Period. It's quite simple and does not lend itself to any exotic study of thermodynamics, wave theory, or "combustion profiles".

I'm sure that your answer will be that I myself am also a self proclaimed expert but in fact I have gleaned this knowledge from schooling and 30 years experience engineering race engine parts and systems.

Sorry for the pointed response but your attitude begged for it.

[KevinMac]

I bow to the self proclaimed experts who know nothing about the mapping software and insist that the scanner watching the sensors tell the combustion profiles! No longer worth the discussion! Do what you like it's your vehicle!

Such a stubborn, condescending view begs for other opinions. Here's my 2 cents. It doesn't take a "self proclaimed expert" to know that there is fuel in the tank without using a dipstick. The expert can monitor the fuel level gauge and if there is no reason to disbelieve the gauge, he can tell the level from it.

Much in the same way, a "self proclaimed expert" can monitor the "combustion profiles" (boy there's a twenty dollar phrase) by monitoring knock sensors and ignition timing "profiles". The knock sensor feedback is quite simply a monitor of "There is detonation" or "There is no detonation". Period. It's quite simple and does not lend itself to any exotic study of thermodynamics, wave theory, or "combustion profiles".

I'm sure that your answer will be that I myself am also a self proclaimed expert but in fact I have gleaned this knowledge from schooling and 30 years experience engineering race engine parts and systems.

Sorry for the pointed response but your attitude begged for it.

Pointed response or not my response was based on the attitude of another!

That's interesting, you ever write any mapping firmware! Have you ever developed digital interface of OBDII diagnostics into a technician terminal. Have you ever wriiten or even seen tuning software and remote engine monitoring software?

Well I probably know the answer to that, and if you can just say that since you have a knock sensor that is the cure all, you are way off.

The limitations of the maps can only go to the a low threshold! So depending on the threshold written into the firmware will be the determing factor.

Even if the knock sensor continues to hear it does not mean that detonation will cease! A knock sensor is tuned to listen

in the 5khz range. Combustion chamber cylinder bore and temperature are charateristics that vary knock frequencies. Engines typically have muliple vibrations modes. So in reality depending on the condition the design or location of the sensor may not pick up all the knock. It is not unusual for one cylinder to knock and not be detected due to the transfer function of the cylinders and engine characteristics. In addition, the base reference of the sensor has to be set low for knock detectiion above idle speed. There may be times a knock sensor to shut off above 4000rpm make more dependency on the ECU maps to prevent knock in this range. The sensor can actually not pick up 100% of the knock based on variables mentioned. So now add in 87 octane which may or may not cusae issues! Thus my point in my posts. Another point od f which I agree that a knock sensor goes from base to no knock condition, but that means nothing based on the design and other factors mentioned and if the maps cannot correct then it makes no difference if it hears it or not. The Maps are wrtten for fuel economy, emission standards and performance. With all factors considerd. The outcome is a limitation of the stock firmware.

As an engineer one would think you know this!

Nice try though!

Since this all came from someone making a mistake on using the correct octane, the article I referenced in my above posts backs that 87 octane will have it's problems in a Porsche 996.

Have a great day!

[rsligar]

Does anyone happen to know what the highest octane is that you should run in a 2002 boxster S? I can only get 91 in CA but do have race gas available locally. I think it's over 100 octane though. Would there be any noticable advantage to running a higher octane if I could keep within the maximum? I don't go to the track, just on the street.

Thanks,

Ryan

2002 boxster S

Palm Springs, CA area

[KevinMac]

Does anyone happen to know what the highest octane is that you should run in a 2002 boxster S? I can only get 91 in CA but do have race gas available locally. I think it's over 100 octane though. Would there be any noticable advantage to running a higher octane if I could keep within the maximum? I don't go to the track, just on the street.

Thanks,

Ryan

2002 boxster S

Palm Springs, CA area

rslinger - I do not have any info to say if anything above 93 will net better performance. ihave heard that 100 in higher temop condition works well, but no validation if iti s true. I know if you go too much it will go negative. Think you might want to ask the question on some porsche race sites

[wwest]

I bow to the self proclaimed experts who know nothing about the mapping software and insist that the scanner watching the sensors tell the combustion profiles! No longer worth the discussion! Do what you like it's your vehicle!

Such a stubborn, condescending view begs for other opinions. Here's my 2 cents. It doesn't take a "self proclaimed expert" to know that there is fuel in the tank without using a dipstick. The expert can monitor the fuel level gauge and if there is no reason to disbelieve the gauge, he can tell the level from it.

Much in the same way, a "self proclaimed expert" can monitor the "combustion profiles" (boy there's a twenty dollar phrase) by monitoring knock sensors and ignition timing "profiles". The knock sensor feedback is quite simply a monitor of "There is detonation" or "There is no detonation". Period. It's quite simple and does not lend itself to any exotic study of thermodynamics, wave theory, or "combustion profiles".

I'm sure that your answer will be that I myself am also a self proclaimed expert but in fact I have gleaned this knowledge from schooling and 30 years experience engineering race engine parts and systems.

Sorry for the pointed response but your attitude begged for it.

Pointed response or not my response was based on the attitude of another!

That's interesting, you ever write any mapping firmware! Have you ever developed digital interface of OBDII diagnostics into a technician terminal. Have you ever wriiten or even seen tuning software and remote engine monitoring software?

Well I probably know the answer to that, and if you can just say that since you have a knock sensor that is the cure all, you are way off.

The limitations of the maps can only go to the a low threshold! So depending on the threshold written into the firmware will be the determing factor.

Even if the knock sensor continues to hear it does not mean that detonation will cease! A knock sensor is tuned to listen

in the 5khz range.

Aha...!

Your knowledge is out of date by a goodly number of years....

Technology has moved on.

The 4-5Khz resonant knock sensors were abandoned by most marques more than 5 years ago, probably more like 10 years for high performance cars such as Porsche. The new wide-bandwidth non-resonant sensors can not only detect knock/ping but also actually detect the initiation of the flame front and thereby determine, via comparison with the crank position sensor, if the flame front "beginning" was correctly cognizant with the spark ignition.

From reading the material on the subject it appears that if the detonation is prior to spark ignition the corrective action will be to enrich the mixture as retarding the timing would just be detrimental.

Combustion chamber cylinder bore and temperature are charateristics that vary knock frequencies. Engines typically have muliple vibrations modes. So in reality depending on the condition the design or location of the sensor may not pick up all the knock. It is not unusual for one cylinder to knock and not be detected due to the transfer function of the cylinders and engine characteristics. In addition, the base reference of the sensor has to be set low for knock detectiion above idle speed. There may be times a knock sensor to shut off above 4000rpm make more dependency on the ECU maps to prevent knock in this range. The sensor can actually not pick up 100% of the knock based on variables mentioned. So now add in 87 octane which may or may not cusae issues! Thus my point in my posts. Another point od f which I agree that a knock sensor goes from base to no knock condition, but that means nothing based on the design and other factors mentioned and if the maps cannot correct then it makes no difference if it hears it or not. The Maps are wrtten for fuel economy, emission standards and performance. With all factors considerd. The outcome is a limitation of the stock firmware.

As an engineer one would think you know this!

Nice try though!

Since this all came from someone making a mistake on using the correct octane, the article I referenced in my above posts backs that 87 octane will have it's problems in a Porsche 996.

Have a great day!

[KevinMac]

Actually the current knock sensors are broadband single wire and flat response two wire knock sensors. My response is up to date. If the sensor was responded to for all harmonic frequencies it would never allow the engine to run at it's full potential since engines harmonics are not all due to knock. They still have their specified window! Therefore a base line has to be configured. Once agan a knock snsor is not the cure all!

Think this topic is worn out!

Edited August 14, 2008 by KevinMac

[wwest]

Actually the current knock sensors are broadband single wire and flat response two wire knock sensors. My response is up to date. If the sensor was responded to for all harmonic frequencies

But, just as you said, the sensor does "respond" to all (harmonic??) frequencies.

Its the ECU firmware that "sorts" things, the various frequencies deemed of importance, out.

it would never allow the engine to run at it's full potential since engines harmonics are not all due to knock.

They still have their specified window!

WINDOWS, nowadays...

Therefore a base line has to be configured. Once agan a knock snsor is not the cure all!

Think this topic is worn out!

Methinks you maybe need an education in/on DSP, Digital Signal Processing. With the newer inexpensive and SUPER fast processors modern day engine control ECU firmware is well able to "sort" out the various frequencies (frequency bands, really.) and their crankshaft position, timing-related, "meaning" and react/adjust the engine control parameters accordingly.

A single day's subscription to techinfo.toyota.com and a complete and comprehensive reading about the modern day use of knock sensors in/on the diagnostic sections would probably suffice.

AND...

Why go to the additional expense of wide-band sensors if you're not going to take advantage of the new capability...??

Edited August 14, 2008 by wwest

[KevinMac]

Let's not go there you have no clue what my backround is! You really are just throwing around what you see on the internet, and have no idea how it ties together!

Just for your education, firmware is written to meet certain criteria the manufacturer is seeking. So go read some more, and get an education on Software and Digital circuitry developement! Then we can have an intelligent conversation! The sensor will hear more but does not mean it's a cure all. There is more to it then just a listening device!

Your previous posts says all that is needed to know you are just arguing for the sake of arguing!

BTW the tie to the crank position sensor is a method to try narrow down to what cylinder is pre igniting, therefore allowing individual cylinder control as apposed to introducing broad control. In no way provides any control, it's just a data flow! The ECU will decifier to the appropriate cylinder, and attempt to adjust. Still does not mean that the ECU can accommodate the knock below a paramter that is setup in the firmware. By introducing 87 may be well below the adjustable parameters. Like I said it is how the manufacturer has written it's firmware.

You quoted all the tech words out of the glossary of some document but can you tie it together! "ME THINK NOT"

Once again am not saying the Porsceh ECU cannot, all I am saying is to many speculative comments are being made without knowing the manufacturers parameters. Nowhere in any of their documentation do they say you can run 87 as other manufactures say you can!

So until someone can provide Porsches acceptance of using 87 then there is no need to continue with this!

Enough said!

This thread needs to be closed!