Sigma 150 - possible stuffed immobiliser?

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Bone Rat
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Sigma 150 - possible stuffed immobiliser?

Hi to all,

I was wondering if I could pick some brains about what is 'normal'. I've got a 2011 SIgma 150 Roadsport which I tend to look after myself. Cambelt done professionally but all servicing is in house. Up to now all has been fine. 

In September I was driving along the A48 at Bridgend when the car just stopped running when I stopped at one of the major roundabouts. Not good being stuck in the outside lane of a fast A road. Pushed to the side and waited for the RAC. The engine would turn over, fire for about a second but not run. There was a spark, the fuel pump primes, the TPS was fine. After a few hours by the side of the road - a big thank you to Dave in Porthcawl for checking up on me, I got home on a flat bed.

Since then have checked over repeatedly, it turns over, fires but doesn't run for more than 1 -2 sec. Have browsed the site and changed TPS and lambda to no effect. Earths cleaned, battery fully charged, new plugs 2 years ago (3k miles), inertia wotsit checked & bypassed.

Checking the immobiliser today, it's the Sterling type with the dongle and loop around the lock. The LED does not illuminate at rest at all, on turning the key to the power on position it gives 1 flash then nothing, turning off it gives 1 flash then nothing at all. There is no steady light when in the starting position or flashing LED when the key is removed.

I was just wondering if the collective experience of the elders would be that it's not working correctly and stuffed. If so any suggestions about what to do or where to go, would this be a job for a local electrician to  sort? I am game to remove one after many years of dealing with 1970s Fiat electrics! 

Many thanks 

Andy

Jonathan Kay
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Private Message sent.

ChrisC
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I can't help think the immobiliser is fine if it primes and runs for a few seconds. The fuel pump is controlled by the ECU, it wont run is the engine isn't running.  So it makes me think the MBE isn't happy the engine is running.

Have you connected it to EasyMap to see whats going on?

I could be wrong about the immobiliser.

I owned a 2011 150 Sigma, and I remember a fault which would cause the engine to die, which was caused by the speed sensor.  The sensor would fail, kill a fuse and that would take the permanent supply out from the engine and tacho.   Check your fuses, if you one blown and it keeps blowing disconnect your speed sensor and try again.  

richy
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Contact MBE in Cirencester if you think the ECU is faulty. They are very helpful.
7 wonders of th...
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sounds like the fuel pump feed / earth is being lost for normal running and its just running on pump prime pressure then stops

Bone Rat
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Thank you everyone, they can be incredibly frustrating little cars at times. Winter is going to be interesting

Andy 

John Vine
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Re #5:

That's how it appears to me, too.  The crank sensor (or its wiring) would be a prime suspect.

JV

7 wonders of th...
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Have you also looked at the TPS and the harness...?

Bone Rat
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Hi, 

Yes, checked the various threads on the forum, unfortunately it seems a common set of symptoms. So far have a new lambda sensor as that had been in 10 years and was covered in soot. No joy. 

Then replaced the TPS and the small harness (it was on offer), again no joy.

Yesterday, tried looking at the fuel pump and wiring, have cleaned the earths in the engine bay, the plug at the fuel pump looked fine with clean contacts, fuses are fine. It's odd in that the pump primes, it turns over readily enough, fires, runs for a few seconds, just as if it's on the priming pressure and dies.

The mass of other connections seem buried above the gearbox and would tax a gynaecologist to get to, at least via the engine bay 

7 wonders of th...
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Easiest access to those is by taking the tunnel cover off.

Garth
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The immobiliser on my Sigma did fail several years ago - had an auto electrician diagnose it - the red LED was not doing what it normally did which prompted me to investigate this. From memory however the car would not turn over - completely dead so probably not the immobiliser! 

The other problem I had once which behave in a similar way to what you describe is a damaged wire to the crank sensor?

Good luck