1985 + 928s on Low Octane Fuel?
07-13-2016, 10:42 AM
#46
Rennlist Member
On 1985-1986 Porsche 928 32valve U.S models there is a (green or brown not sure) wire called the octane loop on the fuse panel, when connected, it retards the timing for use of low octane fuel since these model year have no knock sensors. I've tried it once and noticed a loss of power and lower mpg, so you don't benefit from saving if mpg and power drops. Low octane fuels have less cleaning detergent causing carbon deposit. Same with my v6 VW Passat with knock sensor, less power with less mpg using low grade vs premium.
07-13-2016, 01:54 PM
#47
Instructor
It's not actually on the fuse panel, but near it. Attached to the EZF and LH harnesses at the plugs are two sets of wires. the pair on the EZF is green/blue, the pair on the LH is brown. Each side has a M and F connector (the ones on the EZF are longer for some reason). You connect them to each other to form the "octane loop".
07-13-2016, 02:13 PM
#49
Inventor
Rennlist Member
Rennlist Member
Holy thread recycler, Batman!
I found that my S3s would run fine on 89 octane (AKI, 92 RON) with the stock chips. The long duration cams and/or smaller valves (or?) make the S3 engines fairly knock resistant.
Connecting the EZ-F plugs (green wires) shorts the air temp sensor. Shorting or disconnecting the IAT retards high-load-cruise/WOT by 6°, IIRC. It is meant for temporary use only.
Connecting the LH2.2 plugs (brown wires, stock chip) selects a slightly different O2 sensor map but has no noticeable effect on driving.
EZK is 87- with knock sensors. (No need for an octane loop.)
I found that my S3s would run fine on 89 octane (AKI, 92 RON) with the stock chips. The long duration cams and/or smaller valves (or?) make the S3 engines fairly knock resistant.
On 1985-1986 Porsche 928 32valve U.S models there is a (green or brown not sure) wire called the octane loop on the fuse panel, when connected, it retards the timing for use of low octane fuel since these model year have no knock sensors. I've tried it once and noticed a loss of power and lower mpg, so you don't benefit from saving if mpg and power drops.
Connecting the LH2.2 plugs (brown wires, stock chip) selects a slightly different O2 sensor map but has no noticeable effect on driving.
EZK is 87- with knock sensors. (No need for an octane loop.)
