(G) No Spark at plug

Hi , Out of the blue on Wednesday my scie would'nt start in the morning , the engine turned and turned but not even a cough or splutter from it , when I came back in the evening and tried it , first turn and started , ran here and there and it was back to normal , next day thursday ok ran perfect , next day Friday was an action replay of tuesday , would not start , later on I tried again , started and it was fine all night , Saturday morning no joy turned and turned the engine , not even 1 fire-up or cough or splutter , took plugs out = no spark , anyone had this strange behaviour ? saturday evening still no joy !
Cleaned crank sensor and visual but nothing seems out of place.

Suggestions\advice please anyone , would be appreciated , thanks

sounds like it could be a faulty crank sensor,,,,was there no spark on any of the cylinders?? if its only on 2 then could be one off the coilpacks or H/T leads.

Hi , Thanks for the reply , I only tried 2 plugs for a spark in between trying other things i.e. checking leads etc. it's quite difficult to chack for a spark working on my own as I had to ask a neighbour to turn the key while I checked , maybe I should have taken the lead cap of and tested the HT lead's on there own as I should not be trusting plugs at this stage but 4 going at the same time ? The crank sensor was really quite dirty but seemed to clean up well , do you know if there is a way to test this on it's own because really at this stage it could be any of a few things , trial by elimination seem's to be the strategy here . but it's knowing which area is most likely . Thank's again .

Join Clubcento and you'll get the nominal values of all the sensors.

Cheers

D

you can check a cranckshaft sensor with an ohms meter, if your getting a very high resistance then there could be a break in the coil inside the sensor but if it is doing this intermintantly then this may be hard to find.
depending on sensor type ohms can range between 500-1500.
if i remember correctly

you can also check the H/T leads for a break down in the same way using an ohms meter, shortest to longest you would want to exspect around 4.7, 5.7, 7.6 and 8.5 ohms for the longest set on the (20k) setting on the meter (for the cinq sporting).
just incase you wanted to no

If you can jiggle the cable around while you're testing the crank sensor you might catch a wiring problem.

but remember if you do as above the connector will have to stay on and you will have to prod into the wires to test using the meter,,,usually you would remove the muliplug and test directly to the sensor.

Cheer's guy's will try another shot at it today , Thanks for advice .

Of course, you could just disconnect the sensor and do the woggling! The wiring to these is pretty tight and exposed, so seems to break down quite often.

So if the crank sensor was faulty would there be any spark from the engine at all ?

correct if it's an 899 check the wiring to the crank sensor as they have a habit of getting chewed up by the ancillaries belt were it drives the water pump

From the plug lead's that is ? Anyone ?

Sorry did,nt see reply there . Not chewed but wondered if they are known to knacker internally and if so would the symptom be no spark at all at the plugs as this is what's happening , Can anyone give me a rough breakdown of what the crank sensor really does so I can get a grip of the theory side of it's workings as my knowledge consists of the old school of distributors and points etc.
Typical job's I've done on my scie are > Clutch cable , Thermostat , Rocker Gasket , Brake Shoes so I am adaptable , I just need to know where the problem is as I dont really want to replace anything unnecesary as this takes time/travel/money and it's crap when one replace's the wrong part.
Also if there is a conclusion to this scenario I will document it and also post the symptom's AND fix on Fiatforum so if anyone has this problem , information will be there for them. I have read a lot of problem's people have with their scie's/cinq's but not many people post the fix to the problem once thy have it sorted . Thanks again ..

it tells the engine the rpm and the top dead centre position from this the car knows when to inject and when and witch plugs to trigger either 1 and 4 on top dead or 2 and 3 on 180 from top dead wasted spark system

so if this part is faulty in any way or the wiring for it it plain and simply wont run because it wont spark or inject

if your car is not injecting also and the ecu has power light comes on and goes off and so on then it's a likely cause

if the car is injecting fuel but is not sparking check the common 12v feed to the coils from the injection relay