Sigma Stall.

[Dorset7]

A question for the collective - the 7 has been running fine all day but tonight I went out for another quick blat and decided to stop to take a couple of photos. 

I left the car running and when the fan kicked in the car died. It didn't want to restart for a couple of tries but then fired up fine and drove home faultlessly. 

I fitted DRE shift lights yesterday but only tapped into the + - and signal wires to the tacho so I don't think that's the culprit. 

I'm suspecting a less than optimal battery given how long the car has been stood over Winter without a battery conditioner - thoughts anyone?

[Stridey]

If the DRLs are LEDs , do you have them directly plugged in at 12v or do they have a box to switch them on and off at high rate (quicker than the eye can see) to save on battery? This is why when cars are filmed  on telly you often see the lights flickering on and off, similar to the effect of propellor blades being hard to film.

Our eyes see the lights as permanently on.

I have a vdo voltmeter tucked into the knee panel  on the passenger side so I can see if the battery is charging at 14.5 v on the move. But you can of course check with a multimeter when static.

 

[Dorset7]

Thanks for the reply but I'm referring to DRE shift lights (change lights) not daytime running lights. 

[DJ.]

I'd be surprised if the battery was at fault. If it cut just supplying the fan, it wouldn't turn the engine over. Also the alternator is generally powering everything when the engine is running.

I don't know why your shift lights would affect it, but if I change something and another thing goes wrong, I generally reverse whatever I did and see if it goes back to normal

Another thing that might be worth checking is the current drawn by the fan. If there is some sort of a short in there it might affect the engine idling.

Duncan

[Dorset7]

Thanks for the reply. 

I was kind of thinking along the same lines, the shift lights shouldn't have caused the issue, they don't draw that much and weren't actually active at the time (tick over).

The battery is the original (as far as I'm aware) so might not be in the greatest of states now but it does turn the car over. Tick over might be a bit low (800 -900RPM) but I'm not sure how I could bring it up a bit. I did notice the temp and oil pressure gauges swinging to full deflection and I seem to remember that being an indication of a suffering battery?

I'll get the voltmeter on it later today to see what standing and running voltages are and take a view from there. 

I suspect this might just be an oddity and chances are it'll never happen again!

[elie boone]

Most likely that the engine stalled because of the extra power a rad fan asks of the systems, if your idles is on the low side the alternators demand for extra power can stall the engine. Then the system might have suffered some heat soak. modern electronics don't like it when an engine is stalled, most of the time they take a few seconds to check and reboot.

[Stridey]

Ahhhh dre' s.   Whoops. 

After I had intermittent starting issues (annoying)... I took to packing a mini type lithium starter in my tool bag just in case until I got it all sorted. Still keep it in there. Just to get me out of trouble. Or others... And makes a handy phone charger backup. Needed to use it twice when the fault came back. 

The voltmeter tucked away on the knee panel (visible when driving) just gave me indication as when and if the alternator was working properly. 

I tracked mine down to a faulty alternator. But I did treat myself to a new battery as belt and braces... I use 12v batteries for my race timing kit so the original is used there instead. Along the way I beefed up the earths from the battery, and took the opportunity while working on the alternator to put a proper waterproof plugs on it as it was pretty prone to damp down there. 

I had had enough of parking at the top of hills just in case I needed a bump start. Good luck.

[Dorset7]

That does seem to make sense. 

The issue has prompted me to sort a couple of bits though - new pugs, HT leads and probably battery, I don't know if any of them have been changed since the car was built so a few new bits won't cost the earth and would benefit the car regardless. 

[nickhi]

I had a similar issue (Roadsport 125 3 years old). The Battery didn't seem to hold charge for more than a few days and failed to start a couple of times.  Luckily I also have one of the small phone sized Lithium Batteries (I always carry it in the 7 just in case).  I recently replaced the Battery and now starts bang on every time. 

It may be worth checking the parasitic Battery Drain just in case there is an issue somewhere.  Mine's just on 25mA. 

 

[Dorset7]

Just a return to this one - zipping along yesterday and the car died, just as if the ignition had been switched off. 

Restarted after a couple of tries but idle revs were high.  The car then died again (thankfully on my road) so pushed it onto the drive. 

I removed a plug lead, fitted an old plug and cranked the engine - very weak, yellow and intermittent spark. I checked all the leads the same way and I've come to the conclusion the coil pack has given up the ghost. 

Having researched online it would seem this is a pretty common fault on a range of Ford cars with the Sigma (Zetec SE) engines.

New coil pack ordered (but not from CC at £62!) - I'll post more on the results. 

[Tom_Arundel]

Not sure about your diagnosis (fast idle?) but just for info.

Ford coil packs have been known to fail because the standard Ford plug gaps are set at 1.3mm.            This gap is for low speed - lean burn engines which a Caterham Sigma is not. It takes a lot of volts to         `jump the gap` and at high revs this tends to overload the coils. I use 0.9 - 1mm plug gaps and I          think that Ford reduced the gap to 1.1mm to get over the problem but seem to be back to 1.3mm now, maybe the later coils packs are better

Tom       

 

 

[Dorset7]

After the car started again the second time the idle had returned to where it would've been normally.

I recently changed plugs to the 1mm gap type as per the Focus modification but the car had been running on 1.3mm gap plugs for it's whole 6 year life (to include two years racing).

Other than plugs (new), leads (newish) and coil pack theres not much else to change, unless I've an ECU problem. The new coil pack should be here today so I'll report back after a day of testing tomorrow (weather dependent!)

 

[Dorset7]

Update - new coil pack fitted and car runs nicely now. Whilst the bonnet was off I had a look about and found a vacuum hose (?) running from a sensor (I think) to a port on the underside of the throttle body - both ends of the pipe were split and not sealing very well allowing air to escape.

I trimmed both ends of the pipe back and refitted - seems to have done the trick!

[DJ.]

Good to hear it's sorted for the summer

Thinking back, I can remember problems with cold idling of my 125 which improved when I found the map sensor pipe was disconnected. Sorry, I'd forgotten all about it.

[SM25T]

Split hose ..... good spot. Easy to miss.

[Dorset7]

Well after 1.5 hours of hard blatting things seem to be tip top. 

The car is running better, smoother and more responsively, whether it was the MAP sensor pipe or the coil pack I don't know, maybe a combo of the two but who cares - PT Sports Cars here I come!!!!!

[Dorset7]

Well, I thought I had things sorted but it would now seem I don't!

The car drove faultlessly to Windsor from Dorset yesterday morning but on the way home I had the same issue - on the M3 the car just cut out, I lost all power and it wouldn't restart.

Once I was recovered to the services I tried turning it over again and it fired up nicely. I drove it all the way home with the AA guy following and it never missed a beat!

I'm at a loss to think what it might be. the new coil pack made the car run more smoothly for sure but it seems it was just a happy coincidence and not the root of the problem.

I'm starting to wonder if it's linked to fuel as when the car died I had about a quarter of a tank left and before heading home with the AA guy I filled up.

The only other explanation is something to do with the shift lights I fitted recently using the signal feed to the tacho and the + and - feeds to the tacho.

I really need to get this sorted but I'm stumped - does anyone have any ideas?

[martyn]

Have you had it plugged into a laptop while its exhibiting the problem yet?

[Dorset7]

The AA guy plugged it in but the MBE ECU wouldn't talk to his computer, I'll have to get it to a specialist I guess but i really wanted to try to sorrt it out myself to avoid the expence! 

[Delbert]

2 left of field thoughts from a mechanical numpty

1) is there an issue with the imobilser

2) The cut off thingy when the car rolls have you tried a reset

 

Only reason I ask is FiFi was cutting out very occasionally at Curbourgh the other day  

The collective wondered about the imobilser then some one reset the roll over cut out button

 

Fine since

[revilla]

Have a look at this thread, particularly towards the end, for information on communicating with an MBE.

[Dorset7]

I did have a look and reset the inertia switch but it appeared to have no effect on the starting issue, I was hoping it would be something simple along those lines.

The immobiliser is a potential I guess but, as I understand it, the Ford system is pretty good and faults are unusual but it's always a possibility! 

Sadly I have visions of the car on a trailer to CC and a huge bill for diagnostics!

[martyn]

As mentioned above, standard automotive OBD readers wont read the MBE ECU.  It is however very easy to do and should be your first step.  Dont pay anyone to do it, plenty of people on here (myself included) have the necessary cable.  Its a worthwhile investment if you run a car with an MBE ECU.

It sounds though like you may have an intermittent wiring gremlin somewhere.  But first you need to rule out a faulty sender.. plugging into a laptop will tell you that.

[Dorset7]

So......I think I've worked it out!

I think the shift lights were the issue - I just spoke to the nice people at SBD who produce the MBE ECU on my car.

When fitting shift lights the ECU needs to be configured for the additional item if you use a feed from it. I simply spliced into the signal wire that runs to the tacho from the ECU this, it would seem, confuses the ECU as it doesn't recognise the shift lights and can cause issues.

This all makes sense given that I had NO running issues until the DRE shift lights were fitted.

Unhelpfully Caterham lock all their ECU's and so SBD are unable to perform any retrospective programming or other work.

I've disconnected the shift lights now and all seems well at present - I'll come back with any further issues if there are any. 

[martyn]

Interesting, absolutely no problems with the Caterham supplied ACES lights fitted in exactly the same way.