Today I took the car from the official dealer to test it for the week end and off course the christmas tree is alive and kicking (after 1 month in the shop)
I spoke with the mechanic that is in charge of my car and he said to me that he cannot see a relation between the dash lights and the coils and that they don´t have new coils for my car to try and test them.
So my only chance is to buy new coils in EEUU,change them and prey (I already changed the battery and the problem was not solved)

 

You should try and get him to come to rennlist 964 . We will talk with him .
When the spark leaks from the ignition system , the dash lights up .
Its crazy but true .
The spark might be leaking from one of the two coils or from one of the two distributors or from one of the 12 / 14 ignition wires .

 

Thanks Indycam, I wish mechanics here in Buenos Aires understood english, so I could say to them: read it in Rennlist you .....
I will start by ordering new coils as they are cheaper than the wires, if they don´t solve the problem I will continue with spark wires.

 

And because he said he does not see a relation between coils and christmas lights , tells me he is not looking in the right place .
He should be checking the ignition system for a leaky spark , tracking on the tops of the coils , caps inside and out , rotors . Also a break down of insulation on all the ignition wires .

 

You should start by doing a few little tests , before spending a penny .

 

Find another who does speak english and lets talk with him ?

 

My old coils ohmmed out per spec, but my Christmas tree went away after I replaced them. A coil can spark internally while still appearing fine with the low voltage from the multimeter. Get the car on an ignition scope if you want to test the coils properly. If the coils are factory original, you are not wasting money if you replace them based on age alone.

 

Thanks guys
I already ordered the coils (from Vertex) if they solve my christmas tree I will be a happy man, if not, next stop spark wires+rotors + distr. caps.
I am probably going to sell the car anyway, after solving this problem, because I developed a strong nasty feeling about this car.
I will continue to love Porsche´s but my 964 experience has been one of great unhappiness.
Maybe a 993 in a few years???

 

New coils fixed my intermittent Christmas Tree.

And don't fall for the "check them by disconnecting one at a time" suggestions. Car ran fine on either of my old coils, but it is a beast by comparison with the new coils!

 

Thanks altarchsa !!!
I surely hope same happens to me, but I´m selling the car anyway

 

Hi chaps

Just to add to this post - My car has thrown up Christmas tree light for
a while now and last week it started stalling if I allowed the car to idle.
The exact symptoms were as follows:

1. Uneven idle. The rev counter wouldn't really show the fluctuations,
but the car would rock/shake at idle and hunt.
2. Often after a long drive (about an hour or so) as I decelerated to an
idle, all dashboard lights would flicker on and sometimes the loud warning
buzzer would sound. This would continue until the car was restarted.
3. As the problem worsened, if the car slowed to a stop, the engine would
idle for a while, then falter and stall.

Solution: I fitted two new Bosch coils (about £75 for the pair) and cleaned
all the connecting lead terminals.

I have run the car for two days and all of the symptoms are gone.
Additionally, as others have reported there is a marked increase in
engine performance (beyond the subjective). The engine is far more
responsive from low revs to mid-range.

Aaah! that's better

 

We swapped out the ECU, checked the complete wire harness, changes the caps, rotors, plugs and wires but the Christmas Tree effect persisted. Finally I read that new coils would solve it so I ordered a set. 2 years later and I've never had another problem. If I were to run accross the problem on another 964 the coils would be the first replacement part. No doubt the other tune up parts were called for but I believe the coils had some internal leakage that was feeding back to the ECU through the hall effect circuit.

 

Hey Springer can you tell me what the readings were and how you measured it on the coils?

i have two "suspect" coils on the bench (bosch) readings are similar but one was causing the primary bank to not fire...

 

It has been two years and I no longer recall the values. I looked up the normal ranges, think the in the service manuals. Both coils were in spec and similar to each-other. The VOM applies low-voltage DC. The operating voltage at the HV secondary is whatever it takes to break down the gap in the spark plug - typically 4000 volts or even higher if the plugs are worn.

Mechanical movement of the windings, or cracks in the insulation inside the coil, can cause the spark inside the coil rather than at the spark plug. The DC resistance is not affected, and the car can even run OK if the spark goes to the plug most of the time.

 

I know you said you replaced the battery without success, but you might want to change your battery ground strap. I had the same Christmas Tree problem after having changed coils/ignition wires/caps/rotors and replacing the battery only to have it be a faulty (or bad chassis connection) cable. I replaced the strap and haven't seen the problem in 4 months. Its a cheap repair. You can also try the water mist at night trick to see if your wires or coils are arcing.