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964 System Adaption - advice appreciated

thesmithsUK

Well-known member
Joined
7 Dec 2014
Messages
372
As always, my 964 started first time on Friday. Then immediately stalled. And again. And again.

Only with some rapid right footwork could I keep it from stalling. As soon as I moved off, though, all was fine - the idle behaving as normal at junctions, lights, etc.

A few hours later, same thing. And again yesterday. It seems unable to find its initial idle, but sorts itself once on the move?

Some forum searches lead me to think it may need a system adaption.

Does anyone have any experience of doing this themselves? Is it a straightforward DIY job - e.g. with the T-OBD / Scantool software? (My regular indie is 120 miles away!)
 
Try removing your ISV (Idle stabilisation valve) and cleaning it with MAF cleaner, while your there also clean the MAF and the MAF barn door.

ISV is often to blame for what you have describe.
 
This is probably bonkers... what's more I now can't find the thread where I read this...

Supposedly the throttle pedal has a sensor to detect when pressure has been applied; sometimes an overmat can push up and slightly depress the pedal preventing the engine from idling.

I had a day where my 964 just would not idle, regardless of how warm the engine was. Later I did a lot of searching of the net, found lots of suggestions - ISV cleaning being one of the more popular - but also this idea of the floor mat. I intended to go straight back and see if it made any difference, unfortunately it was not until the following weekend. I did re-position the mat and naturally all was fine, no further issue.

But I'm very sceptical; I should have repositioned the mat the same day whilst the engine was playing up.

Any grain of truth in the pedal sensor idea?

Mark
 
Im pretty sure the 964 has a micro switch to tell it when its off idle so a slight depression of the throttle pedal would make the car think its not at idle .

The usual cause for this though is as mentioned .. the idle valve , cleaning does work but not always .

Moveing on from that then an emissions check would be a good start to see if its running rich / weak .

http://forums.pelicanparts.com/porsche-964-993-technical-forum/343285-hunting-idle.html
 
Yes, as above.

Clean IsV and check it moves freely and check that the idle micro switch is being activated. Do these before plugging a 'pooter in. As the other chap said it can also be related to a faulty 02 sensor...

Oh, and the millions of pipes :D

Mine has always idled poorly too when cold and interestingly got no worse after a light weight fly wheel was installed... Will get to the bottom of it soon when i've got it back together...
 
after we had our 964 C4 off the road for 4 months a few years ago while it had a 993 6-speed gearbox/front diff and then Bilsteins all round, we had a similar issue when it would cut out suddenly such as approaching roundabouts and traffic lights just before coming to a stop - it was fine driving along

before then, it just wandered a bit around at idle - well it is an old car and basic electronics :lol:

I cleaned the ISV and it made only a small difference - it sort of stumbled then died. We then had it hooked up via the OBD for correction and was lovely - for about 10 minutes until we stopped for petrol and then behaved as before

i then found this article on RL (below) and it improved immensely - moving only a tiny bit off target idle speed and no longer cut out - perfectly acceptable. Then a few months later, it was in at JAZ for service and they tightened up the rubber hoses on the inlet manifold bananas and now it is absolutely 100% rock steady. it is perfect and just like a new car

I always start it without throttle since and wait maybe 30 seconds from cold and it hasn't stalled or misbehaved since :thumb:

HTH

---->

DME 7.8
DME 7.8
PEIN2DME78
0
Printed in Germany – 14, 2003
Note on adaptation
The DME control module must perform a learning and adaptation
routine for the throttle adjustment unit if:
♦The power supply to the DME control module is interrupted
♦The DME control module plugs are disconnected
♦A new DME control module is installed
♦The throttle adjustment unit is replaced
♦The DME is programmed.
To do this:
1. Switch the ignition on for 1 minute without starting the engine.
Do not actuate the accelerator pedal (for instance, make sure
that there is not a carpet pressing on the pedal).
2. Switch off ignition for at least 10 seconds.
The following conditions must also be observed, otherwise learning
is not possible:
♦Vehicle is stationary
♦Battery positive voltage between 10 V and 16 V
♦Engine temperature between 5 °C and 100 °C
♦Intake air temperature between 10 °C and 100 °C

<----

:thumb:
 
Thanks all. Removed the carpet; followed the 1-minute ignition procedure above...and bingo - it's been fine ever since! Lovely drive to and from work today (20 miles round trip) - happily, Cornwall doesn't do winter!
 
:thumbs:

Glad to hear that :)
 

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