P8 in Fiat Fire, test coils, fuse blows

[Peter15]

Hi everyone

I started this project, p8 on Fiat fire 1.2 8v turbo.

I connected the main air and water sensors, throttle, camshaft, map, injectors and single coils of the Ford focus code FI1TA 4M5G-12A366-BC.

The engine has no cam sensor.

I created a starting map.

Before trying to start it I'm doing the injector and coil tests from the Display and test function menu, but as soon as the test starts and the coils start the fuse blows.
In General engine setting External Coil Amps is off and Twin Spark is on. I tried to turn off Twin Spark but the fuse still blows.
Do I have to activate the External Coil Amps with these coils? if I activate it the system warns me: do not turn this on with an un-amplified coil connected, severe damage to the ecu can result.

Can you help me? Thank you

[stevieturbo]

You do not state what size fuse

From what I can find on google, it's a 2 pin coil, so almost certainly inductive. External amps should NOT be checked.

twin spark only needed if you do not have a cam sensor.

If you run the test with the coils unplugged, what happens ?

One at a time ?

And is it wired as per instructions ?

[Peter15]

You do not state what size fuse

From what I can find on google, it's a 2 pin coil, so almost certainly inductive. External amps should NOT be checked.

twin spark only needed if you do not have a cam sensor.

If you run the test with the coils unplugged, what happens ?

One at a time ?

And is it wired as per instructions ?
[/quote


Tomorrow I'll try disconnecting the coils and connecting them one at a time.

10 amp fuse

no cam sensor

wired with 4-pole relay and fuse

[stevieturbo]

10A fuse for the entire system ? or just the coils ?

a 4 pole relay ? odd thing to use on a car ? Most are single pole.

test with no coils, then with one. Then try each coil position at a time, single coil and see what happens.

Stick a current clamp on the offending circuit and measure current during this too

[Peter15]

10A fuse for the entire system ? or just the coils ?

a 4 pole relay ? odd thing to use on a car ? Most are single pole.

test with no coils, then with one. Then try each coil position at a time, single coil and see what happens.

Stick a current clamp on the offending circuit and measure current during this too

I used some of the original wiring.
original Magneti Marelli relay and fuse, 10 amp fuse for coils and injectors, relay and fuse for fuel pump.

the P8 wiring diagram indicates a 30 amp general fuse.

4 pin single pole relay
30=12v
86= key
85= negative
87= 12v output for coils and injectors.

the other relay wired the same with negative 85 connected to the output pin of p8 for the fuel pump.

Could the electrical system be undersized?

in the morning I'll try as you indicated Steve, thanks.

[stevieturbo]

I prefer to fuse specific runs/items

Fuses are to protect wiring, not usually components ( unless located close to the component, and sized appropriately )

Personally, yes you could have a 30-40A fuse overall, if wiring thereafter permits this size and you opt only for a single relay. But I would still fuse items after this.

eg
a fuse for coils
a fuse for injectors
a fuse for any other actuators etc

It can help with fault finding too to isolate things.

IMO 10A for the entire system seems a small fuse. But again, test it, measure actual current draw and go from there.

If using a 30 or 40A fuse, make sure all wiring after that fuse is safe to carry such loads.

[Peter15]

Problem solved.
fuse and relay under sized.
I tried one coil at a time and then on 2 and 3 the original 10 amp fuse blew.
I also noticed that the relay heated up immediately.
I replaced it with a 30 amp relay and fuse and now everything works.

started....

Now it's mapped

thanks Steve for the tips

[stevieturbo]

In lieu of multiple fuses, I'd get a current clamp and monitor overall load when used hard if you can. Then you can run a fuse as low as you need to.

ie, if the circuit normally only ever pulls 15A, there's no need for a 30A fuse.

Odd that the relay was heating up though, even micro relays are mostly 20A or above. Standard size relays I thought were pretty much all 30A, occasionally 40A

But at least it was an easy fix

[Peter15]

Once the fuse problem was solved, another one arose.

During starting the injectors do not open, while they open during the test the injectors and coils.
The revolutions are there because the display shows them and the pump turns during starting.

ideas?

[stevieturbo]

So this was a running engine ? everything working ?

And now you say only the injectors do not open ? all injectors ? have you tested for power and an ecu trigger ?