joker2cv

Hello guys,
I'm italian and i like this forum very much! I don't speack english very well so i'm sorry for any mistake...
I have a little problem with my '88 951 S: the spark at plugs is weak, a little orange, not blue. I have just changed the coil, the ignition wires, the distributor and rotor.
I changed the DME ignition transistor (1012) with a new one (BU941ZP).
Could you help me?
Thanks

audisport

Just to make sure, you changed the plugs also? Is this on every cylinder or just one?

theedge

How are you testing?

joker2cv

Yes, i changed the plugs.
For the test i disconnect a wire and i connect at it another plug and i ground in to the engine: i start the engine and i look for the orange spark....

Ronin-951

Ground Wire from Block to Firewall gets REALLY crusty under the intake and next to the Turbo. If their original's, think about a complete replacement.

joker2cv

I checked all ground points yet and the Dme and klr ground too...

Black51

New spark plugs, what is the gap set at? The next thing might be the alternator, especially if it's original, then the battery.

Paulyy

have you tested the coil?

http://www.clarks-garage.com/shop-manual/ign-04.htm

joker2cv

Thanks for yours answers!
I'll do the coil test.
A short time ago i measured the coil resistance: the primary circuit (15-1) was about 1,1 ohm, the secondary was about 6kohm.
The coil is an original Bosch and i bought it 6 months ago. I checked the old one too and the values are the same.

@BLACK51: why are you thinking to the alternator?

Black51

Well, if the battery is not being charged, the spark will get weaker and weaker until the battery dies and the engine doesn't run.

What is the spark plug gap set at?

joker2cv

The GAP is 0,7 mm. I think that the alternator is ok because with the engine running i see 13,5v at the battery. I cleaned the ground point in the engine bay and on the engine too, but are there some others points? ( under the dash?)

Dave W.

The main ground is next to the battery. It's slightly hidden by the rubber hood seal. Also make sure the spark plug is grounded to a clean spot on the engine or the test may not be valid.

There is a table in the DME that increases coil dwell time when battery volts gets low, so the spark should stay the same regardless of battery volts. This table is useful since the starter will drain a few volts off the battery.

joker2cv

In the meaning of the coil test, i have another question: can an erratic setting of RPM or TDC sensor cause my orange spark? I have checked both resistances and were good, but i haven't a scope to see them wave

Dave W.

Possibly. Maybe the rotor is loose and not lined up?

joker2cv

I know that the 2 sensors (RPM & TDC) have to be adjusted at 0,8mm from the flywhell: i have never cheked it, only them resistance (OK). I don't know what happens if they are not adjusted: perhaps the engine will not start? Other?