2x Momentary cut out - any ideas?

[NeilHopkins]

Hi everyone

I'm new to this Roadster thing and already rolling my eyes (fairly sure that is part of the ownership experience, right?)! The beast in question is a 03 Roadie with sports pack and c84k on the clock.

Just got it back from the garage after having some "TLC" (lots of new hoses, engine mounts, battery terminals etc - oh and a full service. Because I'm endlessly optimistic, I took it to a Smart garage for its first service under my ownership. Left kidney is mortgaged.). My other half took it out for a run - all fine.

I took it out today on precisely the same route and it cut out twice. It's worth saying that we were on country roads with medium/heavy traffic so some enthusiastic progress but not booting it by any stretch of the imagination...

1st time, slowed down and stopped to queue for some temporary traffic lights. Facing slightly downhill. It just stops after all the lights on the speedo come on. Not huffing or puffing. In a later vehicle, I would have said that it was an automatic traffic light cut out (but not this. I'd driven it for a bit before it went to have its tummy tickled in the garage and no sign of any such gizmos).
It turned right back on without any drama and away we went. I assumed that there was something like a stall when we slowed down OR that it was because I turned the radio volume up to see if it worked (it doesn't. The thought that this may have caused a power drain did go through my mind) as it cut out at exactly the moment the radio volume was somewhere around max.

2nd time, driving downhill (in case anyone knows east sussex, down the hill heading west towards cuckmere haven!) - at first I thought that a particularly bright shaft of sunlight lit up all of the dash lights - nope.
The really odd thing is that the engine didn't stop. In fact, had it not gone into Auto (I was using the flappy paddles), I may not have actually noticed at first. Having had all lights on for what seemed forever (maybe 10seconds, probably less), it just left the !triangle on. Drove very carefully but didn't notice any appreciable changes - left it in auto and it still shifted when i expected it too. Was super light on the accelerator just-in-case but it didn't seem to drive any differently.
Got within a mile of my house and went back to flappy paddles - fine.

Got it back home and left it idling on the drive while we put the roof up. All seemed groovy. Turned off and on again, warning triangle goes off.

Just started it up now to move it back out of the garage to have a poke about inside, all seems fine. No warning lights or anything.

I've got my head under the driver's side and can't see any fuses sticking out and no evidence of water around the fuse box/SAM.
I've stuck my head as far as I can into the engine bay and the earth strap looks OK (what I can see of it).
I've looked at the battery and all terminals seem to be attached and the connections to the car body look fine.

So... A touch mystified. Can you help? I've seen various things about crank position sensors, so wonder if it could be that?

IT's worth saying that there's a swimming pool in the passenger side. We're drying it out as best we can with cardboard, towels etc. Think that the people we bought it from gave it a jet wash before selling...
Drivers side seems totally dry. I'm not sure if that it is a useful piece of information, given that the cut out happened when facing downhill (and with 2 people in the car) each time but thought that I'd mention.

Thanks in advance!

[Mr T]

First thing i'd do would be to plug in a code reader & see if any error codes have been logged.
The crank position sensor does sound plausible. They normally fail when at tickover & hot & as soon as they cool a little seem to repair themselves!

[NeilHopkins]

Ok cool - which code reader is best as there seem to be a few out there?

And, sorry if this is a dim question, would it work on other cars too?

[Mr T]

Any generic OBD11 reader will work, some Smart specific codes won't show.
I don't know if you've found http://www.evilution.co.uk A great font of knowledge & well worth the subscription if you're into tinkering.

[NeilHopkins]

Thanks Mr T - scanner is on its way now so let's see what that shows...!

[Thrumbleux]

Have a look at the last page here >> http://smartmaniacs.co.uk/forum/the-...ne-cutting-out
From memory it was SAM related - but repairable.

FQ101 is also a useful resource.

[NeilHopkins]

Thanks for the link Thrumbleux!

I bought a StreetWize scanner and plugged it in. Instructions say to wait for the display to show CAN OBD2.

After about 10 mins it still just says SW OBDIi. Is that normal (if anyone has used these? I bought it because their website said it would do for a Roadster!)

[Thrumbleux]

I've never used a scanner - I have Delphi (Chinese clone) on a laptop - so can't comment. These things do sometimes take a few attempts to connect.

[Mr T]

I've used several different scanners over the years & to be honest never noticed what OBD it said. I just worked my way through the menus to get to where i needed.
BTW, you have got the ignition key switched on?

[NeilHopkins]

All seemed fine re returning fault codes (none!) even though the first screen didn't say what it said it would!

[NeilHopkins]

Update - took it out and all seemed ok so my other half said "Shall we carry on for a bit longer as it's behaving itself?"

Obviously the phrase of doom as 5 mins later, while idling outside Lewes prison, all off. Cue hooting from angry 4x4 owners in the queue behind us as we struggle to get it started.

No code showing when we get it to a safe spot and plug in the code reader.

Behaved pretty impeccably all the way home - left it idling on the drive for a few minutes to replicate the experience of being at the traffic lights - nothing (obviously) awry.

So, if it is the cam sensor, how difficult are these to replace? Is it the sort of thing that a competent mechanic should be able to do? If so - any recommendations near to Seaford in East Sussex?

[Thrumbleux]

Crank position sensor - your engine doesn't have a cam position sensor. - if it is that at fault.

[NeilHopkins]

Thank you - that's what I meant!

[Thrumbleux]

Forgot to mention, the CPS is a PITA to change. Access is difficult and they more often than not are seized in place and don't want to come out so I'd not rush to change one on mere suspicion.
The usual symptom is engine dying at idle and as yours has cut out on the move and can't (as yet) be provoked into dying during idling, maybe worth giving it a bit longer to worsen in line with expected behaviour.
I'd have thought there'd be a a code but as their failure is fleeting (when warm) and they come good quickly when cooled- maybe hard to capture?

[NeilHopkins]

So far it has died 3 times - twice at traffic lights and once on the move. So I feel like I'm in s bit of a quandary - from where I live, most of the roads are rural-ish or there's the main A27. If it cuts out on the A27 that would be no fun esp if at speed and going uphill. If it cuts out on a rural road there's not many safe places to pull over and not block a carriageway!

What else could it be (the wiring connections look ok - I have checked the thread of SAM solder too but not yet popped it out)? I would like to be able to drive it a bit without worrying over the next couple of months!