Has anybody here done the alfa 75 twin spark engine change to 74 gtv? i am having problem with coils not sparking also one of my coils got so hot that it melt down.any idea??
thank you
sam
thank you
sam
sam
Sam,
How is your ignition set up???
If you are burning up coils, it sounds like they are on 100% of the time, never switching off- which sends the power to spark the spark....
Do you have points?
Check out the ignition thread on this same section- it shows the basic points electrical layout.
If you are using the stock trigger, you need a computer to deal with that- as far as I know, all of the 75's TS ignition is electronic, and requires at least an amplifier, if not a module to turn the 100-2 pulse weel into a ignition system....
Eric
How is your ignition set up???
If you are burning up coils, it sounds like they are on 100% of the time, never switching off- which sends the power to spark the spark....
Do you have points?
Check out the ignition thread on this same section- it shows the basic points electrical layout.
If you are using the stock trigger, you need a computer to deal with that- as far as I know, all of the 75's TS ignition is electronic, and requires at least an amplifier, if not a module to turn the 100-2 pulse weel into a ignition system....
Eric
Sounds like the ground signal from the ignition amps to the ECU isn't working properly.
The module should not power the coils all the time when the key is on, just when the engine spins- for exactly the same reason you point out- burnt coils.
I'll assume that your ignition boxes are not intelligent, so that they purely operate off of the ECU high and low signal. Which should be low with the engine off, and the coils should not have power going through them. Perhaps 12V ready to arm them, but not the ground line.
I would first check that the I/O between the ECU and the amplifiers are correct. Do you have a wiring diagram? They should NOT go to a basic ground, but to ignition pins only.
Anyone out there know which pins on a 75 TS are the ignition pins???
Eric
The module should not power the coils all the time when the key is on, just when the engine spins- for exactly the same reason you point out- burnt coils.
I'll assume that your ignition boxes are not intelligent, so that they purely operate off of the ECU high and low signal. Which should be low with the engine off, and the coils should not have power going through them. Perhaps 12V ready to arm them, but not the ground line.
I would first check that the I/O between the ECU and the amplifiers are correct. Do you have a wiring diagram? They should NOT go to a basic ground, but to ignition pins only.
Anyone out there know which pins on a 75 TS are the ignition pins???
Eric
I have a 1969 GTV with a twin-spark (ex Alfa 75) in it.
I don't know if I can help with your wiring - in fact I have an
intermittent electrical problem of my own (engine dropping to
idle up hills or when accelerating). I suspect the wiring because
twice the problem has vanished after I lifted the loom on the
left front side, near the battery and towards the relays. I've
switched all the relays around, replaced the ignition power lead
from the battery, and various other things. I'm at the point of
pulling this part of the wiring loom apart and replacing all the wires
in it, but I can't find a wiring diagram for the t-spark to guide me.
Can anyone help me?
I don't know if I can help with your wiring - in fact I have an
intermittent electrical problem of my own (engine dropping to
idle up hills or when accelerating). I suspect the wiring because
twice the problem has vanished after I lifted the loom on the
left front side, near the battery and towards the relays. I've
switched all the relays around, replaced the ignition power lead
from the battery, and various other things. I'm at the point of
pulling this part of the wiring loom apart and replacing all the wires
in it, but I can't find a wiring diagram for the t-spark to guide me.
Can anyone help me?
G'Day Cliff,
You can't have looked very hard, see the link in my sig and download the Alfa 75, Twin Spark 'S' manual and look in group 00 (page 71 75TS_S-00-71.gif).
Cliff and Sam,
Below is a description of what the ECU does when you turn the key, read it in conjunction with the diagram.
The four relays on the firewall are (from left to right, This may be
different on your car).
S12a Fuel Pump
S12b Motronic
S12c VVT
S12d Aux Motronic
Turning on the ignition switch (to run or start) provides power to S12a
(Fuel Pump Relay) switched contacts (but does not turn S12a on) and turns on
S12d (Aux Motronic Relay).
S12d (Aux Motronic Relay) provides power to the ignition coils, power to
S12c (VVT Relay) (but does not turn S12c on) and turns on S12b (Motronic
Relay).
S12b (Motronic Relay) provides power to S12a (Fuel Pump Relay) coil (but
does not turn S12a on), provides power to pin 35 of the ECU, provides power
to the Idle Actuator (but does not turn it on) and provides power to the
injectors (but does not turn them on).
NOTE! S12b must have a diode inside it or in the Green/Black wire going to
it.
When the ECU detects the engine is turning (via the CrankAngleSensor) it
turns on S12a (Fuel Pump Relay).
The ECU now controls the Ignition Coils, the Fuel Pumps (both together), the
VVT, the Idle Actuator and the Injectors.
Hope this helps,
You can't have looked very hard, see the link in my sig and download the Alfa 75, Twin Spark 'S' manual and look in group 00 (page 71 75TS_S-00-71.gif).
Cliff and Sam,
Below is a description of what the ECU does when you turn the key, read it in conjunction with the diagram.
The four relays on the firewall are (from left to right, This may be
different on your car).
S12a Fuel Pump
S12b Motronic
S12c VVT
S12d Aux Motronic
Turning on the ignition switch (to run or start) provides power to S12a
(Fuel Pump Relay) switched contacts (but does not turn S12a on) and turns on
S12d (Aux Motronic Relay).
S12d (Aux Motronic Relay) provides power to the ignition coils, power to
S12c (VVT Relay) (but does not turn S12c on) and turns on S12b (Motronic
Relay).
S12b (Motronic Relay) provides power to S12a (Fuel Pump Relay) coil (but
does not turn S12a on), provides power to pin 35 of the ECU, provides power
to the Idle Actuator (but does not turn it on) and provides power to the
injectors (but does not turn them on).
NOTE! S12b must have a diode inside it or in the Green/Black wire going to
it.
When the ECU detects the engine is turning (via the CrankAngleSensor) it
turns on S12a (Fuel Pump Relay).
The ECU now controls the Ignition Coils, the Fuel Pumps (both together), the
VVT, the Idle Actuator and the Injectors.
Hope this helps,
I am in the process of building one to go in a 67 GT. The best I think is use an Electromotive ignition and loose the injection. This way the car will be easier to work on. Besides nothing sounds better than a big pair of Webbers. Does anyone know where I can purchase a set of Cosworth pistons. 86mm bore and 11.0 compression???
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