DME reset when engine is COLD or HOT?
10-11-2004, 09:48 PM
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DME reset when engine is COLD or HOT?
I keep reading about resetting or remapping the DME by disconnecting the battery. However, should this been done when the engine is HOT or cold? Or no big diff? 
10-12-2004, 05:25 AM
#4
DME reset is ideally done when the engine is warm. This is because you should be able to use all gears and a wide range of revs and throttle inputs. If you reset the DME when the car is cold, all the car learns is that you drive like a feline.....not good.....
10-12-2004, 06:31 PM
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I thought you were supposed to go for a 15 minute spirited drive? It doesn't take me 15 minutes to warm up my engine, so within that window I get a chance to get the revs up a bit. All within the posted speed limits, of course. 
Brian
Brian
10-12-2004, 06:44 PM
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I have an idle problem when starting a cold engine, and wondered whether a DME reset would help. I assumed it might, but only if the DME logged data for both cold and hot engines.
I haven't done the reset yet, as I'm not sure I understand exactly what I am trying to do. Is this muddled thinking?(that had better be a rhetorical question!) Anyone know.....
I haven't done the reset yet, as I'm not sure I understand exactly what I am trying to do. Is this muddled thinking?(that had better be a rhetorical question!) Anyone know.....
10-12-2004, 07:01 PM
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Julian, it really couldn't be easier. Just disconnect the negative battery cable for a while (between 15mins and an hour depending on who you talk to), then drive it like you stole it for 15-20 minutes! And here's what Adrian has to say about the reset:
I didn't know any of that stuff. That guy's a genius. 
Brian
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
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
Brian
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10-12-2004, 07:16 PM
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Brian,
Thank you for that, very kind. I am a definitely a fan of Adrians, and he has been kind enough to help with a few words of advice now and again.
I shall pull the DME tomorrow and see what transpires!
Best wishes
Julian
Thank you for that, very kind. I am a definitely a fan of Adrians, and he has been kind enough to help with a few words of advice now and again.
I shall pull the DME tomorrow and see what transpires!
Best wishes
Julian
10-12-2004, 08:09 PM
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Originally Posted by JEJ 149
I have an idle problem when starting a cold engine, and wondered whether a DME reset would help...........
I am beginning to think its the paint color though
LOLActually, I do believe its my light fly wheel and the stock DME that is driving me crazy
I have ordered a new chip that should help......but we will see....Anyway, I have to leave the accelerator down and the RPM above 1,000 to keep the car alive for about 90 seconds...then its run's amazingly well. Its the first 90 seconds that are incredibly difficult to keep the engine running.
10-12-2004, 08:38 PM
#10
The chip didn't solve the problem on my car, but running a system adaptation did. It still stalls every other week or so when the engine is cold. Note: I also don't have a AC, but I think there is a trick by unplugging the AC wire and turning on the AC on the dash to solve the stalling due to the RS Flywheel.
10-16-2004, 08:14 PM
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Well I finally got my new GIAC chip from EVO ( http://www.evoms.com/p%20964%20computer.htm ). Took two extra weeks to get than promised, but worth the wait. I'm not entirely convinced that EVO version of the GIAC chip is anything different than GIAC's standard chips. The packaging and label of the chip looks to be directly from GIAC. The chip version was stated as "450 GLO 3.02C" (450 is the DME version, GLO I understand to be the initial’s of the owner of GIAC when he loads chips himself - only told that from another vendor so who knows, and I assume that the software version is "3.02C". ) Hopefully we can compile a version history with dates.
One interesting note is that the chip is actually on a daughter board that has a small additional chip on the bottom. I didn’t take a picture of it
If I ever have to get back inside the DME I definitely will. Because of the increased thickness (due to the inclusion of the daughter board) the stock plastic lock cap that goes over the chip could not be used. But the chip is VERY snug so that’s not a real worry.
Getting the DME circuit boards apart was a much more difficult ordeal that I expected. My DME looks a bit different then most of the instructions I have found. It looks like this open with the top row of plugs separating (difficultly) from the bottom rows
Once installed there are some definite differences. The car stabilizes in about 30 seconds rather than 2 mins when cold now (but I've only had one morning to test things). The engine is just running awesome with this chip....pulls HARD and I can’t wait to take it to the track next weekend. I can still get it to stall with the A/C on if I do something really abrupt, BUT under normal driving it won’t stall with the A/C which is a major improvement.
The most noticeable difference is that the car now idles at 1,100 rpm and with the A/C on it's at 1,000 prm. With the light flywheel the engine rev's very very quickly BUT the deceleration rate is MUCH slower. Before the rpms would drop like a rock, now it is much more smooth and slow.
It will be interesting to see how my impressions change as I have more time to drive it.
One interesting note is that the chip is actually on a daughter board that has a small additional chip on the bottom. I didn’t take a picture of it
If I ever have to get back inside the DME I definitely will. Because of the increased thickness (due to the inclusion of the daughter board) the stock plastic lock cap that goes over the chip could not be used. But the chip is VERY snug so that’s not a real worry.Getting the DME circuit boards apart was a much more difficult ordeal that I expected. My DME looks a bit different then most of the instructions I have found. It looks like this open with the top row of plugs separating (difficultly) from the bottom rows
Once installed there are some definite differences. The car stabilizes in about 30 seconds rather than 2 mins when cold now (but I've only had one morning to test things). The engine is just running awesome with this chip....pulls HARD and I can’t wait to take it to the track next weekend. I can still get it to stall with the A/C on if I do something really abrupt, BUT under normal driving it won’t stall with the A/C which is a major improvement.
The most noticeable difference is that the car now idles at 1,100 rpm and with the A/C on it's at 1,000 prm. With the light flywheel the engine rev's very very quickly BUT the deceleration rate is MUCH slower. Before the rpms would drop like a rock, now it is much more smooth and slow.
It will be interesting to see how my impressions change as I have more time to drive it.
10-16-2004, 11:03 PM
#13
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The daughter board is GIAC's way of keeping the riff-raff out and stopping anyone that hasn't gone past freshman year in EE from duplicating their EPROM.
