KASH '95 993

I have been experiencing what appears to be excessive timing retard or power loss under hard acceleration in all gears except first (especially between 2,000 to 4,500 RPM).

Does the primary (upper) and secondary coils work simultaneously/ continuously? Or does the secondary coil only comes on at a certain RPM?

If I unplug my primary coil wire, my car won’t start with just the secondary coil connected. However, if I connect the coil wire from the primary coil to the secondary distributor cap the car starts (this rules out the belt).

The next thing I did was to check for current across the secondary coil (with a test light) while the car was running (with everything connect back to normal). I am not getting any current across the secondary coil (only the primary coil). The positive lead to the secondary coil appears to be "live" while the negative lead appears to be "dead" (the test light does not glow across the two leads, however, it glows whenever I go from the positive lead to ground).

Any help figuring out why the negative lead to my secondary coil is dead will be greatly appreciated. Thanks…

chris walrod

Sounds as though the secondary coil is -open-, which makes a coil inoperative. With the engine off, ignition off, can you put an ohm meter across the coil a get a resistance reading of anything?

Steve Weiner-Rennsport Systems

Ken:

Both coils fire simultanously.

If one is inoperative, your timing becomes quite retarded for a "single ignition" engine and thats felt as a noticable power loss.

Sounds like either a dead coil or perhaps a wiring issue.

KASH '95 993

Chris/ Steve,

I do not believe it’s the coil because one of the checks I did was to replace the leads to the secondary coil with the leads from the primary coil and vice versa, only this time the secondary coil and distributor operated properly while the primary coil and distributor was inoperable. So it must be a wiring issue (BTW, this is a MY95 with the original wiring harness).

I am planning on bridging the negative lead from the primary coil to the dead negative lead on the secondary coil when I get in tonight. Do you guys see any potential danger in doing this? Thanks!

Steve Weiner-Rennsport Systems

Ken:

Question: Did your car qualify under the wiring harness recall?

I would not bridge the two as you suggested until you go through the wiring between the ignitor and the coils and make absolutely certain that good continuity exists here.

KASH '95 993

Steve,

I didn't follow-up with the recall memo I got from the dealer, but I believe it did (car was running great and I was traveling like crazy).

I'll hold off on the bridging until further investigation. Steve, two quick questions while you are out there...where are the ignitor and knock sensor located? Thanks!

Thanks for the advice Steve.

Lorenfb

"I am planning on bridging the negative lead from the primary coil to the dead negative lead on the secondary coil when I get in tonight. Do you guys see any potential danger in doing this?" - Kash '95 993 -

Not a good idea, as you could damage the good ignition module.

The possible causes of your problem are:

1. the non-functioning side's ignition module
2. the other signal from the DME unit
3. a wiring problem from the DME to the ignition module
4. loss of +12 volts on the coil

The above assumes that the coil and the coil wire are O.K.

You need to check with a test light to see that the bad coil side
is flashing when running. No light indicates no +12 volts, which
can indicate an open primary on the coil or a shorted ignition
module, i.e. on the "-" side of the coil.

KASH '95 993

Lorenfb,

The +12V source to the coil is "live", but the negative lead from the ignitor (???) is dead. Upon further investigation last night, it looks like the leads to the coils are severely broken down (the insulation was falling apart on all four leads as I attempt to examine the wires). I believe this may have shorted out the ignitor for the secondary coil.

Any idea where the ignitor is located? I was unable to trace the wires all the way back last night. Thanks!

Lorenfb

"Any idea where the ignitor is located? I was unable to trace the wires all the way back last night. " - Kash '95 993 -

The ignition module should be under the drivers seat per the Porsche wiring diagrams.
The 993 uses a single module for both coils versus two modules on the 964.

KASH '95 993

I would have been tracing forever...I'll see if my local dealer has one in stock. Thanks again!

Lorenfb

Before assuming a bad module and buying a new, make sure that the wiring from
the coil to the module hasn't shorted to ground.

KASH '95 993

Will do!

KASH '95 993

Much thanks to you guys....replaced the ignitor and now both coils are firing (all the horses are back!!!)