Premium octane fueling maps

[Mihnea Cotet]

Brett,

I think I have to stop you from the start, the 3Bs are made for running a
minimum RON octane rating of 91. I'm absolutely positive about this one as
91 RON is the lowest available octane rating in Germany and almost all cars
from that era equipped with a cat were made for running on 91 RON at least.
IIRC 91 RON equals to something below 87 (R+M)/2.


HTH,

Mihnea

At 17:37 6/03/2003 -0500, Brett Dikeman wrote:
>At 11:54 PM -0500 3/5/03, Suffolk GameServer LAN wrote:
>>Q:  On 3B motors does it matter the number of starts to get
>>back to the premium octane map in the ecu?
>
>There is an adaptive value or two for fuel quality.
>
>>Reason I ask:  I use 87 octane
>
>The owner's manual says the engine requires 91 octane.
>
>>  and never dip far into the turbo ( in fact car so new to me I
>>haven't but once ) except there are track events where I fill up
>>with super to get the most out of the motor.
>
>It's not a matter of "getting the most out of the motor", it's a
>matter of "not blowing up the motor."  The 20v -requires- 91 octane.
>In the winter with temps so low and charge air temps low as well,
>it's -possibly- OK for now.
>
>Especially if the engine is not chipped, don't waste money on race
>gas at the track.  If you're nervous, find a station with 93 or 94
>octane.
>
>>So back to the 3B: Does the fueling map reset after each start or is
>>there some "proceedure" I should follow?
>
>Ignition retard is quick, but building back up takes time.  I believe
>whereas the CIS units switched back after a certain # of starts(was
>it 20 or so?  Been so long since I owned my 5kCST), the 20vt works
>over time.
>
>The ECU will keep trying to go back to normal ignition timing and
>boost levels, and it won't back off again until it gets knocking.
>
>As for resetting the ECU, pull the two fuses under the red "MOTOR"
>cover in the fusebox, leave them out for a minute or so.  Probably a
>good idea to wait until the ECU has finished the MAF burnoff cycle,
>too, before you yank the fuse- I know disconnecting the MAF or ECU
>during the burnoff will do very nasty things, don't remember if the
>same is true for yanking the fuses.
>
>Resetting should be done any time the injectors(or fuel pressure
>regulator) are serviced, O2 sensor is changed, ISV system is cleaned,
>vacuum leaks are fixed, etc.  Note that you will get poor mileage,
>idle might be off a little too for a bit as the system re-adapts to
>the engine.  I think lambda adaptations are mostly complete after
>about 50 miles mixed driving.
>
>Brett
>--
>----
>"They that give up essential liberty to obtain temporary
>safety deserve neither liberty nor safety." - Ben Franklin
>http://www.users.cloud9.net/~brett/