SPIKES

HI
i have searched achives and get 2 different answers.

after you disconnect the battery ....what is the correct way to re-adapt the d.m.e on 1991 c2?

drive the car for 20 minutes with MINIMUM idling OR idle car for 20 minutes?

thank you

Andy Roe

Disconnect the battery for about an hour. Reconnect & start, but do not stop engine. Take for a spirited >20mins drive using as much of the rev range as possible in as many of the gears as possible.

Andy

Ade - C4 91

Spikes/Andy

I thought that the re adaption should only be done on a warm engine and needs at least 4-5 mins of idle as well to set the idle values. Certainly you wouldn't want to thrash the engine until warmed up anyway - which takes at least 15 mins.

I usually take the car for a good 30min run then disconnect the battery for 30mins. Then reconnect battery, Idle for 5 mins then take for another good 20min run going through as much of the rev range as possible. Seems to work well.



Ade.

Adrian

2 to 3 minutes idle is normally good enough for idle re-adaption. Give yourself time to have a good drive and get as many maps loaded up as possible.
Warm up time depends upon where you live and the ambient temperature of the day.
Ciao,
Adrian
964C4

warmfuzzies

So why not have the engine warmed and ready?
Preperation chaps, warm it, disconnect for an hour, idle for 3-4 mins, then spirited drive, easy.

Kevin

John Boggiano

Well we want it to 'know' how to run and idle cold as well as hot.

Adrian (who by now is entirely sick and tired of this subject, I'm sure) - these 'maps' that the DME stores - are they for specific factors, eg.

cold idle
warm idle
hot idle
full throttle
overrun
coasting
light throttle

or not factors such as these?

Adrian

Dear John,
The maps are recorded data from thousands of bench tests and road tests. They are then pre-prgrammed (loaded) as separate parameters into the DME. The maps are hundreds of thousands of reference points covering rpm, dwell angle, ignition points etc. Combinations of these reference points are loaded up into the volatile memory of the DME via the adaptive circuitry in direct response to how you drive the 964. Each combination of maps correspond to your requirements at the set sampling rate. It is the combination of maps which determine the performance of your 964 because from this data or combination of this data that the DME decides which fuel schedule to use and what part of of a fuel schedule to use. Idle, acceleration, WOT etc.
There are only three items which need to be calculated, engine load, how much fuel to inject and when to blow it up.


A DME reset allows you to remove all the current loaded data and start again. This can change the performance level of your 964 quite considerably. People who have been out on the track observe an improvement in performance but maybe not so good low end operation. The DME adaptive circuitry is always adapting and if you do not change your driving style or reset the DME the data becomes stale and performance is affected. I personally always carry out a DME reset when the weather changes seriously, like autumn to winter and spring to summer.
Ciao,
Adrian
964C4

SPIKES

very interesting.

THANKS ADRIAN AND OTHERS!!