Resetting the ECU on a 993?
Discussion
Hello everyone. Found this place just the other day and you lot certainly seem to know what you're talking about.
My '96 993 was bought when I lived in Germany, if that makes a difference. The handbook and the sticker inside the fuel flap call for 98 Octane so that's what it's always had. Over there 98 was commonplace (and instead of Optimax Shell did 100 Octane Shell Power!) but since coming back to England I've only ever used Optimax.
Got caught out yesterday by the Optimax shortage and ended up having to put in regular 95 Octane to get home. My understanding is the the ECU will have changed mapping to prevent pre-detenation but won't change back when the good stuff goes in, or will do so only gradually. I believe it can be reset somehow, but whether that needs a specialist tool I know not.
Anyone know how to reset it?
Or would you leave it to sort itself out?
And, come to think of it, what octane does a UK spec car's handbook call for?
elfer
My '96 993 was bought when I lived in Germany, if that makes a difference. The handbook and the sticker inside the fuel flap call for 98 Octane so that's what it's always had. Over there 98 was commonplace (and instead of Optimax Shell did 100 Octane Shell Power!) but since coming back to England I've only ever used Optimax.
Got caught out yesterday by the Optimax shortage and ended up having to put in regular 95 Octane to get home. My understanding is the the ECU will have changed mapping to prevent pre-detenation but won't change back when the good stuff goes in, or will do so only gradually. I believe it can be reset somehow, but whether that needs a specialist tool I know not.
Anyone know how to reset it?
Or would you leave it to sort itself out?
And, come to think of it, what octane does a UK spec car's handbook call for?
elfer
All you need to do is disconnect the positive feed from the battery then leave the car for about 20 mins to allow any residual current in the electronics to drain,then reconnect the battery lead and the ECU does the rest on its own once the car is restarted.
Don't know exactly how long the relearning takes but someone here is bound to.
Verysideways are you out there???
Don't know exactly how long the relearning takes but someone here is bound to.
Verysideways are you out there???
As above, except you must disconnect the NEGATIVE battery connection. On reconnection, start the engine and let it idle for about 10 minutes while the car's brain talks to all its sensors and re-establishes the correct settings.
Edited to add - that is if you want to reset the ECU. As they say below, the engine management will try to advance the igntion periodically (how often I don't know) and will gradually re-establish optimum performance.
>> Edited by nel on Saturday 24th December 18:37
Edited to add - that is if you want to reset the ECU. As they say below, the engine management will try to advance the igntion periodically (how often I don't know) and will gradually re-establish optimum performance.
>> Edited by nel on Saturday 24th December 18:37
I believe you also need to really hammer the car once you're back to your proper fuel so the ECU can push the limits. Pussyfooting around for a tank on Optimax won't let the ECU know it can advance ignition a bit. Full throttle up hill in 4th from lowish engine speed will do the job.
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