I'm experiencing no spark coming from my coil on plugs. My wiring harness is from tweak3d and is set up for the black top (I have blacktop ecu + sensors all hooked up).

heres the weird thing - I experience spark when my coil and and igniter are not grounded. It sparks but it back fires like crazy and it throws the engine code 14.

here is a video of my issue https://www.youtube.com/watch?v=JYUUpLVYryY

I don't know how tweak sets up his harness, so I'm just going to throw something
in here that might help. Since you mention coil and igniter I will assume that you
are using three-wire COP's, so this thread...
http://www.86garage.com/forums/viewtopic.php?p=10869

... and this diagram...



... might be of assistance. Code 14 relates to missing IGt (trigger from ECU to COP
to tell it to make a spark) or IGf (from igniter to ECU to say I made a spark) signals.
You will need to identify which wire from your igniter is the ground, and make sure
that it is grounded... not some other wire. Also, each of the COP's will need to be
grounded.

The IGt signal triggers the COP's as well as the igniter. The IGf comes only from
the igniter. Note that this is different from the setup for four-wire COP's.

Cheers... jondee86

jondee86 wrote:Cheers... jondee86

Thanks for your reply. I have contacted tweak'd performance and they verified all the proper locations of the wires.

I added sufficient grounds from engine to body and battery negative to body (sanded down paint). I also replaced the igniter.

Upon these changes I still have the same issue. when igniter is not grounded: i get spark. When igniter is grounded: i don't get spark.

next Im going to add grounds from the throttle bodies to engine block. I've also checked my mechanical timing and gotten it spot on.

my other issue is that when trying to get car to start with the igniter not being grounded, it has mad backfires out of the intake,.


any ideas on what else to try?

jondee86 wrote:. You will need to identify which wire from your igniter is the ground, and
make sure that it is grounded... not some other wire.

Probably should clarify this a bit, as the use of the OEM BT coil is a bit of
a kludge, and an ugly one at that. To satisfy the ECU it is necessary to provide
an IGf signal every 90deg of crankshaft rotation. Since (apparently) the COP's
are unable to provide a suitable signal directly, the OEM coil is retained solely
for the purpose of generating the IGf signal.

The IGf signal originates in the coil as a back emf spike that shows on the coil
negative terminal after the coil has thrown a spark. This spike hits the igniter
and is conditioned into the IGf signal for the ECU. Thus, the coil itself is not
grounded directly to the chassis. The coil negative connects to the igniter, and
it is the igniter that grounds the coil to make a spark.

I'm not familiar with the pinout of the BT igniter, but I would imagine that the
ground will be one of the wires in the plug ? However, if there is no ground wire
in the plug, then either there will be a separate short ground wire, or the igniter
will ground to the chassis thru its outer metal cover and mounting brackets.

The ugly part is that the coil will want to make sparks... and those sparks will
be looking to get to ground any way they can. Some people put a lead in the coil
and ground the free end to the chassis with a bolt. That gives the sparks some
way out and stop them from setting the car on fire.

Backfiring out the intake probably means the spark is happening too early. Does
the engine kick backwards when it backfires ? Try and get the spark timing to
about 10deg BTDC for cranking.

Cheers... jondee86

Update -

I got this to crank up and run once without igniter grounded. no idea how. since then it would just fire once and then die. I'm going to send it back to tweaked to have them look at it if i can't fix it over the weekend. any other suggestions>

try adjusting the CAS in both directions to see if it stays on. timing could be kicked out too far. I had this happen to me, turn the CAS a bit, starts right up, then adjust timing accordingly