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620s - Engine cutting out in very heavy rain


Phillip Meyer

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I was caught in a tropical style downpour today whilst stuck in traffic. The Caterham really didn't like it and was not running smoothly after a short while, seemed to be misfiring and a bad smell. I managed to bunny hop to a fuel station and hide under their roof. It seemed tO be okay after drying out but then I had the same problem again after the rain stopped but with very wet roads.

I'm currently waiting for it to dry out a second time, fingers crossed it will be okay now the sun is out.

However, should i by worried that it's done some damage?

Any thoughts on the cause so I can avoid this happening again if caught in the rain?

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It was insanely wet, like a tropical storm, good job I only had the aeroscreen on!

It worked better after a while but then I had the problem intermittently all the way home until it stalled about 10 mins from home. Then after a restart worked absolutely flawlessly which is Also odd.

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#8  Just checked mine as I was caught in a biblical storm this morning coming back from CC Gatwick, and fortunately they were dry as a bone. Given the lip/rubber seal tightness on my coils to get water down to the plugs you'd really have to be unlucky.

To check.....

Remove coil cover, 2 torx screws, watch out for the fibre washers that are either side of the cover for the screw

5A446F30-E508-43B1-89B3-C2FD8A4804DD.jpeg.8d0a7185258718252db7903e41d24e53.jpeg
Remove individual coils,  undo 8mm bolt and pull.

4D247D62-20DA-4B3A-A2D0-FF778C32B6A3.jpeg.d76b3c7bc2d1324ff8dbaaaa79a09db7.jpeg

Look down hole *wink*

Good luck!

 

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It turned out to be the lambda sensor that needed to be replaced (which is slightly worrying because it was only replaced 3/4 weeks ago, although I have driven ab0ut 1,000 miles!). They said that it was really coked up so I don't know if that was caused by rain or just use. They also said that they updated the mapping as this should help stop the problem going forward.
Maybe I will start carrying a spare lambda sensor with me in the boot.

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Well, lambda sensors should last a lot longer than that!  The coking-up suggests that you're running much too rich.  Could that be due to the perennial over-cooling problem afflicting 620s?  If so, the ECU will be assuming the engine is in warm-up mode and be specifying a richer mixture.  Was the map update intended to weaken this mixture setting, I wonder?

JV

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I suspect that running cold abs therefore rich is the cause. Hopefully the new map will help. Caterham might get fed up with getting the car back every 4 weeks for a replacement lambda sensor, especially as they told me that it doesn't affect the engine's longevity.

To be fair to Caterham cars, they have been absolutely fantastic and jumped on every problem immediately and fixed it while I wait. I can't fault them on that, excellent after sales service. 

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I am away at the moment so had to cancel my track day due to the rattling noise, I suspect it's something in the gearbox otherwise it would happen in other gears. It is back to Caterham on Monday.

I could return the car and ask for a different one but I could have another set of problems with that.

I love the 620, once the Caterham warranty expires I may go to PGM and have their upgrade. In the mean time I will try covering a part of the radiator, any recommendations on which bit to change and how, silver foil?

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blanking part of the radiator as a temporary fix

Temporary? this works for me every winter on the Crossflow when I want the engine to get warm, so that I can get a bit of heat into the cockpit.  Nothing wrong with this, I got the idea from taxis in London.  Cost: £0.

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I wouldn't use silver foil. It's electrically conductive, and it might end up somewhere where you wouldn't want that.

I've seen mention of corrugated plastic sheet and of aluminium sheet.

I don't think that the position on the radiator matters. It only needs to be one side, and I'd put it in front.

https://duckduckgo.com/?q=site:lotus7.club+radiator+blanking

Jonathan

 

 

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Lambda sensors are sensitive to damage from water. They are meant to be mounted vertically in the exhaust (the top of it) so than any condensate drips off the shield and does not enter into the sensor in liquid form. It is electrically heated during start up to avoid contamination. But Caterham seems to have missed that bit in the design, and I suspect that is why we see so many failures.  It is possible water was forced through the exhaust joint if there was standing water.

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To shield the radiator I use plastic correx sheet cabled tied to the inside of the nose grill.
About 1/3 area covered I found works for my 620R ...... however .... that's when the outside ambient temperature is less than 10 degrees i.e. winter, you shouldn't need it atm.
 

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My 620s runs at 90 if it's hot weather and I'm driving around normally BUT if I head onto the motorway it drops right down to between 50 abs 60, especially as I pull off the motorway (then it drops right down). Also in the morning when it's not as hot it is very hard to warm up, it generally sits just below 60.

I think long term I will go down the PGM solution but this will obviously invalidate my warranty so I will wait until that has expired.

I would be really interested though if the coke could be caused by the water or just running rich, the Caterham cars engineer told me it was coked up.

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