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tyinsky
Hockenheim


Joined: 29 Jun 2012
Posts: 696
Location: London, UK

1997 Porsche 993 Carrera 2S

PostPosted: Sun Mar 10, 2019 11:16 am    Post subject: Technical question on knock sensors and remapping Reply with quote

For those of us that have remapped the car, usually this is done on V-Power at the most common place to get it done. What happens if you can't get V-Power and have to use regular for a tank or two? Or even longer?

Does the knock sensor still adjust within parameters or is it better to have a bottle of octane booster in the trunk just in case. Then unhook the battery so it resets back once the good stuff is back on tap.

Since the rebuild I have fueled exclusively on V-Power, but there will come a time this year when that's going to be unrealistic...

 
  
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Endoman
Barcelona


Joined: 11 Apr 2011
Posts: 1386
Location: Bolton U.K.


PostPosted: Sun Mar 10, 2019 12:37 pm    Post subject: Reply with quote

You should be ok in the States if you stick to premium grades which is 97 RON equivalent. I would carry a can or 2 of octane booster if you get stuck in some backwater. The ignition will retard if knocking occurs, not sure if it needs an ecu reset. Depends I suppose on what chip you run, if in doubt stick your std chip back in.
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andyobro
Monza


Joined: 02 Nov 2007
Posts: 165
Location: Poole


PostPosted: Sun Mar 10, 2019 6:44 pm    Post subject: Reply with quote

My car had a 9tuning chip when I bought it, long story short when the chip was causing issues, the 993 would go into a kind of limp mode, the only syptom was that the rev limiter would cut in at 6000 abruptly rather than softly at 6700ish. I guess you would get the same if the knock sensor had been activated using lesser fuel.
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tyinsky
Hockenheim


Joined: 29 Jun 2012
Posts: 696
Location: London, UK

1997 Porsche 993 Carrera 2S

PostPosted: Mon Mar 11, 2019 6:08 pm    Post subject: Reply with quote

Thanks both. Thumb
 
  
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ras62
Hockenheim


Joined: 20 Jan 2012
Posts: 641
Location: Cheshire


PostPosted: Mon Mar 11, 2019 6:30 pm    Post subject: Reply with quote

Wayne will have left a margin when setting the car up so I doubt you would have any issue even running on normal 95 all the time, higher octane just gives a little extra. The knock sensors are the final failsafe and will retard the ignition upto 6 deg iirc.
 
  
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Magic919
Suzuka


Joined: 05 Jun 2013
Posts: 1191
Location: Berkshire


PostPosted: Mon Mar 11, 2019 7:57 pm    Post subject: Reply with quote

For it to run fine on 95 and not need the knock sensors, it won’t magically give more on higher octane.
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ras62
Hockenheim


Joined: 20 Jan 2012
Posts: 641
Location: Cheshire


PostPosted: Tue Mar 12, 2019 10:05 am    Post subject: Reply with quote

Magic919 wrote:
For it to run fine on 95 and not need the knock sensors, it won’t magically give more on higher octane.


Appologies as my post wasn't very clear. I wasn't suggesting more power just an increase in the margin before the knock sensors would be needed.
If forced to use a lower octane fuel then I would avoid big engine loads and high revs especially if the engine is running hot i.e in City traffic.
 
  
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