Hi All, any help appreciated on this one as I am very close to taking my lump hammer to my wife's Brava :bang:

The long version is below, for people who don't want to read all that here's the short version-
Car drives okay (albeit very hesitant on accelleration while on petrol (drives perfectly fine on LPG though)
Has had new injectors recently, new coil pack recently and was driving fine.
Coming home from work one very hot after noon last week and the car just died and has refused to start ever since, I have just replaced the crankshaft sensor as there was spark at the plugs and this has made no difference.
The engine spins over no problem but it refuses to start on petrol orLPG due to no spark.
There is a fault being recognised by the ECU as the injector light comes on when cranking the engine.

I have an elm323 OBD reader, fiat 3 pin to OBD conversion cable and lapop etc but cannot get anything to read the codes.

Long version below-
Right, been driving my wife's Brava to work every morning as it's cheaper to do short journeys than in my Volvo, driving homefor dinner in the afternoon and the injector light came on, I was coasting down hill with my foot off the throttle at the time so thougth I had better check the engine was still running, attempted to acellerate and nothing so had to quickly pull off to the side.
All attempts to start the car failed and after a few tests I found there is no spark at the leads, the coil pack was fitted new about 6 months ago.
Previously on a few occasions while driving the injector light had come on and the car had died for a second but then ran on as normal and the injector light went out.
I have now changed the crankshaft sensor in the hopes that this is the fault (even though resistance readins at the connector check out fine) and the car still refuses to start and has no spark at the leads.
With the engine cranking there is 0.16v at each pin on the connector to the coil pack (all other componenets receiving 12v as they should) what should the voltage be at this connector?

Any help appreciated, I have tried to keep this as short as possible so if any further info is needed please ask away.

Thanks in advance,
Paul.

VolvoV70T5 said:

what should the voltage be at this connector?

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there are 3 wires, 2 are LT input wires, both should have 12v.

the 0.16v signal is just the ecu's feedback loop signal so it can check for any problems during its initial checks (e.g. to see if there is an open or short circuit).

the 12v signal will only occur when you start cranking the engine.

if you dont have sparks on all 4 cylinders it can only be the crank sensor or ecu, or the immob is not disengaging (is code light staying on?), or in some rare cases the cam sensor. chances of both coils blowing at same time is virtually nil, and same goes for the change of all 4 leads or plugs developing a fault at same time.

i'd be tempted to get it diagnosed on a fiat examiner to see what code(s) were stored when the injector light come on.

Hi Jug,

Thanks for your reply.
Pretty much as I suspected, just to check though.....if the cam sensor (AKA Timing sensor to Fiat) fails does the Brava refuse to start?
I have always worked with cars where the ECU uses this purely to fine tune the timing after getting the initial base reading from the crank sensor.

If the timing/cam sensor on the Brava engine is 'required' to enable the engine to fire then this could be the fault (which I was hoping to avoid due its position)
That connector, I tested the voltage with the connector removed and while cranking neither of the LPT pins showed 12v as they should, then again possibly with the connector removed the ECU is not bothering to send the 12v due to the coil pack being missing at the time...if you know what Imean LOL

I know what you mean regarding getting the faults read but given the cost involved I will probably put those funds towards a new car for her and just transfer the LPG kit from the Brava to whatever else I get her.

Thanks again,
Paul.

VolvoV70T5 said:

if the cam sensor (AKA Timing sensor to Fiat) fails does the Brava refuse to start?
I have always worked with cars where the ECU uses this purely to fine tune the timing after getting the initial base reading from the crank sensor.

Click to expand...

its an odd one, and i agree usually a dead cam sensor doest stop the engne from starting, but on the fiat twincams it does seem to have that effect, but not always (i think it depends on the nature of the cam sensor fault)

VolvoV70T5 said:

That connector, I tested the voltage with the connector removed and while cranking neither of the LPT pins showed 12v as they should, then again possibly with the connector removed the ECU is not bothering to send the 12v due to the coil pack being missing at the time...if you know what Imean LOL

Click to expand...

when i did a similar test on my GF's punto with the same engine i got 12v with the coilpack disconnected so that shows your ecu is not sending the 12v LT signals.

Hi Jug,

Once again many thanks for your time.

Today I changed the timing sensor behind the cam pulley for a known good one from a spare engine I just bought.
That's now the crank and cam sensor I have changed, as I said the coilpack is recently fitted, and you confirmed that there should be 12v whilst cranking anyway so the fault lies before the coilpack, ruling that out.
However, I would appreciate your opinion-

Do you think that maybe it is possible that a fault has developed in the coilpack and the ECU is detecting this fault (as you said on the 0.16v signal) and therefore not sending the 12v needed at the coilpack?

The service manual states that at the coilpack the central pin (pin 2) is the positive and pins 1 and 3 are the negative for circuit A and B, checking the resistance specs according to the ones given in the service manual their resistance should be .55 to .61ohm on each circuit. where as both circuits on this coilpack are .9 to 1.0ohm.

Cheers,
Paul.

Okay, I have made some progress.

Checking the wiring diagrams and it appears that the coilpack is provided 12v from the multi relay bolted to the bulkhead, this 12v is a constant 12v which is fed through an ignition switched relay, the relay is switching but the constant 12v is dead.
I don't have the basic manual for the Brava but know that the fuse which should be supplying the 12v is (or should be) a 25amp fuse referred to as the 'Injection fuse' and is fed from another fuse in the 'Power fuse box' which I assume is the main fuse box in the engine compartment.
When I apply 12v to the LPG injectors to fill the cylinders with gas prior to cranking, and then apply my own 12v by using my power probe to the power feed to the relay pack the car starts and runs for a few seconds but then the power probe beeps and cuts off which in turn causes the engine to shut off.
I open the gas injectors purely because they are much easier to access than the petrol injectors and without opening the injectors the car does not run.

At least I am making progress LOL

Cheers,
Paul.

oh yeah you're right i remember now! the centre pin was a permanent live and the ecu would earth the left and right pins according to the crank sensor signal.

when i did my tests i was checking for a live on the 2 ecu wires, which is why it only occured when i cranked the engine, but you're right the centre pin should have a permanent live.

you said the supply relay was switching, but it doesnt have a live. the fuse for it is under the black plastic cover at the back right of the engine bay. check that fuse.