Why oh why does my 964 run like a bag of nails every time I disconnect the battery?
#1
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Why oh why does my 964 run like a bag of nails every time I disconnect the battery?
I'm getting really frustrated with my 964. Every time I disconnect the battery to do some maintenance, or if the battery goes flat, the car runs like a bag of nails. The car wont even idle!
In the past, I've taken it to my local specialist, who does an idle adaptation, but to do this every time is just not practical. I've tried everything suggested in these forums regarding a DME reset, letting it idle, then a spirited drive etc. Nothing works on this car, other than the hammer!
My question is, how could Porsche ever design a car that needs to go to a garage every time the battery is disconnected???????? I love my car but this aspect is very very annoying, especially as most DIY jobs need the battery disconnecting. Not to mention garage bills to do the hammer.
Is there a small backup watch type battery in the DME that backs it up for short periods?
Is there something I'm missing? Is there something wrong with my car?
Cheers
TD
In the past, I've taken it to my local specialist, who does an idle adaptation, but to do this every time is just not practical. I've tried everything suggested in these forums regarding a DME reset, letting it idle, then a spirited drive etc. Nothing works on this car, other than the hammer!
My question is, how could Porsche ever design a car that needs to go to a garage every time the battery is disconnected???????? I love my car but this aspect is very very annoying, especially as most DIY jobs need the battery disconnecting. Not to mention garage bills to do the hammer.
Is there a small backup watch type battery in the DME that backs it up for short periods?
Is there something I'm missing? Is there something wrong with my car?
Cheers
TD
Last edited by TEN DOLLAR; 01-05-2009 at 02:45 PM.
#3
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No codes come up when an idle adaptation is done. The car runs fine after using the hammer thing. Unfortunately I don't own one. There must be something wrong with my car if no other car does this when the battery is disconnected.
TD
TD
#4
The DME resets itself if it is left disconnected from the battery for a certain length of time (around 5-10 mins exact time has been debated on this forum a few times).
The trick is to reconnect the battery, start the car and help it to idle for a few minutes using the throttle. Then take the car for a good 20min drive moving through all the gears and driving at varying speeds slow/mid/fast acceleration etc.
Your DME will 're-learn' the optimum settings for your engine. Your car shouldn't need a visit to a mechanic or to be connected to a hammer.
See here for more info: http://www.964uk.com/html/FAQs%20-%20Engine.htm
Another way to ensure your engine will idle correctly (after doing the above), is to slightly tighten all the jubilee clips on the rubber hoses on the intake side of the engine - especially where they connect to the top of the heads. Don't over-tighten, just take up any slack as you don't want to stress the rubber. This should remove any intake air-leaks and your engine should idle beautifully assuming everything else is set-up properly. [ If I had a pound for very grateful every person I've told to do this, I'd have about, er, a tenner! ]
The trick is to reconnect the battery, start the car and help it to idle for a few minutes using the throttle. Then take the car for a good 20min drive moving through all the gears and driving at varying speeds slow/mid/fast acceleration etc.
Your DME will 're-learn' the optimum settings for your engine. Your car shouldn't need a visit to a mechanic or to be connected to a hammer.
See here for more info: http://www.964uk.com/html/FAQs%20-%20Engine.htm
Another way to ensure your engine will idle correctly (after doing the above), is to slightly tighten all the jubilee clips on the rubber hoses on the intake side of the engine - especially where they connect to the top of the heads. Don't over-tighten, just take up any slack as you don't want to stress the rubber. This should remove any intake air-leaks and your engine should idle beautifully assuming everything else is set-up properly. [ If I had a pound for very grateful every person I've told to do this, I'd have about, er, a tenner! ]
#5
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I'd be interested to find out where the 'spirited drive' comes from. Driving the car has never sorted mine. I use the method stated in the car's handbook which is to start the car and let it idle for 15 to 20 mins. It will idle erratically for a while then all of a sudden settle to a constant idle. At this point, the DME is reset. Surely, driving the car and constantly changing the revs will not allow it to do the job properly. Maybe i'm wrong.
Regards
Martin
www.964rsdatabase.com
Regards
Martin
www.964rsdatabase.com
#6
To be honest, my car lives in the garage with the battery-switch turned off and a conditioner connected directly to the battery. After switching the battery back on the idle will generally 'hunt' for around 30 seconds to 1 minute before settling down to a consistent idle. That's all it normally takes.
I THEN take it for a spirited drive of much longer than 20 minutes just to be sure.
I THEN take it for a spirited drive of much longer than 20 minutes just to be sure.
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Thanks guys, I've tried this process many times to no avail. This afternoon I started the car, let it idle for the required time but as soon as I try and pull away she'll stall. With it idling at 850 and then blip the throttle to 1000, it'll die straight away. In other words the car is virtually undriveable!
I just don't get it!
TD
I just don't get it!
TD
#9
Have you cleaned the ISV lately? Just a thought. It really ought to idle without the adaptation being required.
Here is what the Hammer will do:
Here is what the Hammer will do:
Code:
Idle Adaptation "What exactly is a 'system adaptation', and how is this different from a battery disconnect reset of the DME?" The 964 DME ECM has two adaptations: 1. Idle Adaptation - On the earlier 3.2 DME system the idle was set by an external jumper (caused open-loop idle) & then the idle screw was set to "center" the idle RPM. On the 964, the Hammer causes the DME to go open-loop and then causes the DME to "step" to the center for 880 RPMs. This results in the closed-loop idle being "centered" for full regulation. 2. CO adaptation - The 964 DME ECM goes thru a CO adaptation whereby it runs open-loop without the O2 sensor to "center" the CO setting to allow for small variable changes, e.g. air leaks, fuel pressure, so in the closed-loop mode the O2 system has optimal range (similar to TRA in OBDII). Both of the adaptation values are "lost" if the constant battery voltage (pin 18) is removed. #1 above requires use of the Hammer. #2 occurs at initial running after battery voltage "loss". "What happens with the idle in the case of a battery disconnect and no hammer adaptation?" The closed-loop still maintains the target idle of 880 RPMs but it's not optimized for load changes, e.g. the A.C. compressor, the fans, the lights, and the adapted CO setting.
#10
I'd be interested to find out where the 'spirited drive' comes from. Driving the car has never sorted mine. I use the method stated in the car's handbook which is to start the car and let it idle for 15 to 20 mins. It will idle erratically for a while then all of a sudden settle to a constant idle. At this point, the DME is reset. Surely, driving the car and constantly changing the revs will not allow it to do the job properly. Maybe i'm wrong.
Regards
Martin
www.964rsdatabase.com
Regards
Martin
www.964rsdatabase.com
#12
Rennlist Member
battery on and off
i had my battery disconnected many times and have yet to exsperience the problems mentioned.
could it be perhaps the way the battery is being disconected and reconected?
to disconnect, the negative must be reomved first and to reconnect the negative always last.
then when the battery is reconnected ,i turn the key on to let the fuel pump cycle and turn the key off whithout trying to start the car, turn key off and then i go to full start and never had a problem.
could it be perhaps the way the battery is being disconected and reconected?
to disconnect, the negative must be reomved first and to reconnect the negative always last.
then when the battery is reconnected ,i turn the key on to let the fuel pump cycle and turn the key off whithout trying to start the car, turn key off and then i go to full start and never had a problem.
#13
Idle adaption without a "hammer" is done as previously posted by allowing the engine to idle for 10 -20 minutes, without driving or touching anything (like the throttle). Basically, start and walk away from it.
If your engine runs rough initially, I would suggets getting a system check with either the "hammer" or PST2 tester as something may be wrong.
If your engine runs rough initially, I would suggets getting a system check with either the "hammer" or PST2 tester as something may be wrong.
#15
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i had my battery disconnected many times and have yet to exsperience the problems mentioned.
could it be perhaps the way the battery is being disconected and reconected?
to disconnect, the negative must be reomved first and to reconnect the negative always last.
then when the battery is reconnected ,i turn the key on to let the fuel pump cycle and turn the key off whithout trying to start the car, turn key off and then i go to full start and never had a problem.
could it be perhaps the way the battery is being disconected and reconected?
to disconnect, the negative must be reomved first and to reconnect the negative always last.
then when the battery is reconnected ,i turn the key on to let the fuel pump cycle and turn the key off whithout trying to start the car, turn key off and then i go to full start and never had a problem.
I've changed batteries and left it disconnected for varying lengths of time on numerous occasions. It always fires up and idles fine, and runs off-idle without a hiccup.
Agreed.