Fiat Coupe Club UK

Missfire when Start running.

Posted By: Anonymous

Missfire when Start running. - 10/11/2017 07:08

Engine running well when its starts. It same if starting without key, + direct on starter.
Ignition are complete wrong when starter run, shooting back.
Thanks for ideas.

16v turbo -96.

Have checkt earth- to engine. Not check diagnosis yet.
Posted By: barnacle

Re: Missfire when Start running. - 10/11/2017 13:06

16V requires timing pulses from the crank (sensor behind aux belts) and the cam (sensor by battery). Check the crank pulse for clearance and dirt (1mm from memory) and for broken/chafed wires, and this needs an oscilloscope, for the double(?) pulse from the cam sensor. It's also possible for the cam to move on its mount, but unlikely.

A failure of either signal will cause non-starting, but an intermittent signal might cause a mis-timed signal from the ECU. A large earth pulse through the starter current might indicate a poor earth somewhere.
Posted By: Anonymous

Re: Missfire when Start running. - 10/11/2017 14:33

Thanks, but how can it work when engine is running? Have driving 2 hours, not one missing, and i have engine ears. Problem are only when starter run?
Posted By: hsnlpy

Re: Missfire when Start running. - 12/11/2017 19:22

I have almost same problem with same car.Many things did already.On cold days start took time.On hot days no problem.Many places passed also but no solution..

While i start engine on cold days engine crank there is fuel even it smells that misfire and engine stop.After few try only can start engine..
Posted By: barnacle

Re: Missfire when Start running. - 13/11/2017 07:33

When the engine is running, only the cam sensor is used; if the cam sensor fails when running it uses the crank sensor as fallback. It only needs both when starting.
Posted By: Anonymous

Re: Missfire when Start running. - 13/11/2017 08:26

^^ I'm no expert on the 16v but haven't you got that the wrong way around?
Posted By: barnacle

Re: Missfire when Start running. - 13/11/2017 12:33

Um. I may have, will have to check the details. The point being, only one is required once it's working, but both are required to start (no, I don't know why they didn't use a 36-1 tooth wheel with a wasted spark system).
Posted By: Anonymous

Re: Missfire when Start running. - 15/12/2017 16:23

Have change camsensor and rpm sensor crank, and igintion coils. all new parts. still same problem. On monday i got new fuelrelay, maybe something in there are wrong?
Posted By: Anonymous

Re: Missfire when Start running. - 17/01/2018 08:00

Have find the problem. Two cable in the big connector to ECU was loos, think the pressing from beginning be little bad and in this case car not be used for 10 years maybe little corrision to. It was one cable to rpm sensor and one of camsensor.
Thanks for all help and thinking!
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