# Experience running 87 Octane in 2.5?



## vtraudt (Mar 1, 2010)

Car is 2009 and 2006 Jetta with the 2.5 inline 5. 
The recommended gas is mid grade 91 or premium 93 AFIK. 
What experience do uses have with running 87 octane?


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## Reflex 2.5 (Dec 15, 2012)

91 is the recommended, but will happily run 87… basically detunes itself closer to the early 150hp engines.


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## northendroid (Sep 16, 2014)

^^^ ECU via knock sensor pulls back the timing = less power as explained above. 


Sent from my iPhone using Tapatalk


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## vtraudt (Mar 1, 2010)

Will try if I have a logging template for this ECU. Curious if I see any timing pull with 87 oct. 
Conversely: could squeak out a few more HP by tuning of 93 (add some advance). 
Or (done on a few of my turbos cars): purposely add some advance so that the ECU is taking it out (5 degrees pull) on 93 octane, but 'frees up' the timing advance for the fun on the weekend (autocross) with race gas.


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## Reflex 2.5 (Dec 15, 2012)

That’s a big part of the existing tunes for the 2.5… adjust fuel and timing maps. Don’t remember exact figures, but mine (Integrated Engineering stage 1) starts timing advance almost immediately coming off idle. Generally have to write 87/89 octane file and 91/93… not sure how forgiving the ECU is with octane indifference above 91.


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## kieran123 (Feb 2, 2017)

I only run 87 octane as per the inside of the fuel flap. Should I not be?

Edit: Duh, mine is 2012, that's why.


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## Ark83 (Apr 26, 2012)

I know I have linked this b4 on a similar thread a while back but its relevant here. :thumbup:

http://www.superstreetonline.com/how-to/engine/epcp-1007-2010-volkwagen-jetta-proven/


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## Reflex 2.5 (Dec 15, 2012)

^ LOVE that article… actually where my 150hp comment earlier in the thread came from.


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## halbwissen (Jul 20, 2001)

VW recommends 91 octane for maximum performance in CBUA/CBTA models:


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## Ark83 (Apr 26, 2012)

Similar with the older 2.5 BGP Engine










Picture is from this:
http://www.vaglinks.com/vaglinks_com/Docs/ssp/VWUSA.COM_SSP_891403_MK5_Jetta_Model_Introduction.pdf


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## Ronny Bensys (Apr 17, 2014)

According to VW Maintenance - Edition 10.2015, VW specifies RON unleaded, at least 91, also 87 RON, but with reduced power for BGP, BGQ, CBTA, CBUA.

I run 92 EURO octane (89 RON?). Timing is advanced and stable at 6.5-7.0


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## vtraudt (Mar 1, 2010)

Ronny Bensys said:


> According to VW Maintenance - Edition 10.2015, VW specifies RON unleaded, at least 91, also 87 RON, but with reduced power for BGP, BGQ, CBTA, CBUA.
> 
> I run 92 EURO octane (89 RON?). Timing is advanced and stable at 6.5-7.0


Do you see timing pull (i.e. ECU taking timing out) on low grade gas?


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## Ronny Bensys (Apr 17, 2014)

vtraudt said:


> Do you see timing pull (i.e. ECU taking timing out) on low grade gas?


By telling "timing pull" do you mean "timing advance"? The lowest octane I find in my country is EURO 92 which gives me 6.5-7.0 timing advance. I use Torque app and OBDII dongle.


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## vtraudt (Mar 1, 2010)

Ronny Bensys said:


> By telling "timing pull" do you mean "timing advance"? The lowest octane I find in my country is EURO 92 which gives me 6.5-7.0 timing advance. I use Torque app and OBDII dongle.


With "timing pull" we mean the ECU overriding the 'desired timing' (in the tune) with the actual timing. 
When ECU detects parameters (for example knock) that are outside its range, the ECU reduces timing advance. When logging (for example with Me7 logger), it shows the amount of 'timing pull' (from zero to 6 or more degrees' per cylinder, and at what RPM it occurs. 

I assume the 'reduced power' at lower octane is accomplished by 'pulling timing' (advance) out using knock and other sensor inputs.


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## northendroid (Sep 16, 2014)

vtraudt said:


> I assume the 'reduced power' at lower octane is accomplished by 'pulling timing' (advance) out using knock and other sensor inputs.


You got it :laugh:


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## Ronny Bensys (Apr 17, 2014)

vtraudt said:


> With "timing pull" we mean the ECU overriding the 'desired timing' (in the tune) with the actual timing.
> When ECU detects parameters (for example knock) that are outside its range, the ECU reduces timing advance. When logging (for example with Me7 logger), it shows the amount of 'timing pull' (from zero to 6 or more degrees' per cylinder, and at what RPM it occurs.
> 
> I assume the 'reduced power' at lower octane is accomplished by 'pulling timing' (advance) out using knock and other sensor inputs.


Thank you for the info. So I'd like to get your opinion about 6.5-7.0 timing pull with EURO 92 octane. What is the longterm consequences of 6.5-7.0 timing pull?

Any possible remedies to keep the timing advance as close to TDC as possible using OEM parts only?


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