Indycam

The cables being connected this way or that is not going to do anything for the computer .
The computer will not know why the electrons stopped flowing .
It will be unpowered as soon as you pull off the first cable .
Removing the cable that goes to ground first is just for safety .
If you touch the wrench from ground to ground nothing happens .
If you touch the wrench from power to ground , "things" happen .

If you remove the cable to ground first you can touch the wrench from power to anything on the body and nothing will happen .

I had a Brit car that was positive ground .
On that car the positive cable was removed first .

Indycam

The idle adaptation is all about the computer , it only gets the computer redone so it can run the motor well .
What is not stock on your car / motor ?

TEN DOLLAR

Fairly stock as far as I know. It did have a fixed wing but I've removed that as it was too big. It may have been chipped but I wouldn't know where to look to verify this.

TD

amfp

Have not had that problem when disconnecting my battery for over a month many times throughout the years. I do remove the fuel relay and crank the engine twice to get some oil pressure allowing oil to move internally. Then it starts up as quickly and runs as though the battery was never disconnect.

Maybe you have some bad petro...

911URGE

Out of curiousity what are the Idle adaptions values before and after adaptation? The shop should be able to tell you that if you ask next time it has to be done.

Default value is 128 (80h) I believe.

Have you tried swapping a good DME unit with yours and disconnecting the battery to see if the problem goes away?

Have you cleaned both the ISV & AFM unit?

TEN DOLLAR

I reset the DME again this afternoon. I started her up and made sure not to touch the throttle while leaving it to idle for 20 mins. It seems to idle ok now. I can rev her up without the car stalling once the rpm falls.
So it's possible I may have touched the throttle on previous attempts, which messed up the adaptation process.

Fingers crossed all will be well when I drive her. Thank you all for your help.

TD

Poli84

I'm reviving an old thread because I am having the same problems as the OP.
Every time I disconnect the battery, the car will stall on idle.

I've just finished doing what was said above, left the battery disconnected for 10 minutes to reset the DME and then let it idle for 20 minutes without touching a thing.
As soon as I touched the throttle, stall, stall, stall.

I have a new DME in the box, should I try this?
When do i put it in, before I disconnect or while the battery is disconnected?

I have recently replaced both the Idle Control Valve and O2 sensor with brand new Bosch parts (hence the battery disconnect).

Other than a Hammer idle-adaption (which my mechanic tried this morning but it would not take), what next?
I can't get into my mechanic for another couple of weeks but I have squeezed into a different mechanic for next monday if I can't rectify before then.

sy0296

hmmm, interesting. i disconnected my battery before leaving for a business trip about 10 days ago. I get back next week and hope i don't run into the same problem.

PhatPhlatSix

I had this problem and I found if you adjust the closed-throttle stop so that the butterfly is not completely closed, there is less need for ISV intervention. The idle is then less reliant on electrickery...

Poli84

How do you adjust the closed-throttle stop?

PhatPhlatSix

If you look at the linkage on the throttle housing, you will see how the stop works. You will also need to adjust the electrical switch to make sure it comes on at the right point. All this probably best done with the throttle housing off...

porsche mania

Mine has a battery cut off that I use all the time and I never have any trouble starting or getting the car to idle, even with lumpy cams and lightweight fly wheel. I steady the throttle with the gas pedal for a couple of seconds then it always idles fine on its own. I'd try a new dme and also try pushing the microswitch on the isv by hand to see if it sorts the idle. You can also adjust this so it kicks in a little sooner.

wwest

When you disconnect/reconnect the battery the engine control ECU defaults back to the factory roll out the door parameters.

Your "learned" parameters will be recovered after a few drive cycles.

Your problem is that the learned parameters are to far off the default parameters, something is amiss. A good mechanic should be able to discover which parameter(s) are so far off the "norm".