Request for advice, car won't idle

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ScottR400D
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Ctr, once again, I don’t think you’re finding anything unusual. My R400 was like yours sounds when I built it in 2016 and I’ve heard of many the same. 

In the end mine was set to idle at 1200 and it used to hunt around at that, and still wouldn’t idle until it had run for a minute or so. 

The solution for me was to fit RBTBs and have it set up properly; I’m not suggesting you do that (though I found it well worth while!) but I’m sure you can find a way to have it sorted better than it is now. 

L7C
Limitless
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Minty, I too have the same "problem" if you can call it that. New 420r last year, factory built. It's never idled from new so on start up I just throttle it a for a minute or two and all is fine. 

Funnily enough, I have experienced it wanting to stall after high revving then coming to a halt. I mentioned it to Oakmere when in for a service but it's still the same...

I've learned to live with it. No big deal.

CtrMint
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Limitless, yes mine has started that too, it wants to stall after moderate to hard running and not for long either.  It never did this before.  Up to 2500 miles the engine ran faultlessly, yes I had problems with the rad fan and other challenges.  But the engine always ran fine, now the sudden change is a bit weird.

The TPS seems secure and so I can't see how that has moved. I'm wondering if its the 02 sensor, with the amount of brutal overrun bangs that come through the exhaust, might that have killed the 02 quickly?  Googling some of the symptoms for a dead 02 sensor certainly sound similar.

Caterham 420R S3 Lotus Toxic Green,  Caterham 620R S3 Exocet Red. Blog: https://www.caterham7diaries.com
CtrMint
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A set of RBTB would be nice, but it's simply too costly, the wife would do her nut.  Plus the car is unlikely to car to the UK until spring next year, and I'd like to use it between now and late Sept/Oct.  

Caterham 420R S3 Lotus Toxic Green,  Caterham 620R S3 Exocet Red. Blog: https://www.caterham7diaries.com
Limitless
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O2 sensor, now that's quit interesting. It never did it before I had the De cat pipe on. Perhaps this has affected the O2 levels?

StevehS3
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When the lambda failed on my K it wanted to stall at junctions when the revs drop and it struggled to pass the MOT. I plugged a ODB reader in and it told me the heater had failed in the lambda. Swapped it out and it ran perfectly as before.

CtrMint
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Does the decat have an 02?

Caterham 420R S3 Lotus Toxic Green,  Caterham 620R S3 Exocet Red. Blog: https://www.caterham7diaries.com
CtrMint
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I keep being told OBDII readers wont work, only Easymap and the MBE cable, still hesitating spending the 140quid on a cable.

How did you get an OBDII reader working?  Or is the K series ECU more flexible.

Caterham 420R S3 Lotus Toxic Green,  Caterham 620R S3 Exocet Red. Blog: https://www.caterham7diaries.com
StevehS3
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I would have thought so. Unless the ECU has been reprogrammed to run open loop it will still need a lambda.

StevehS3
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The standard K engine like mine uses the standard Rover ECU so can be read with a normal ODB reader. I don’t know about other engines or ECUs which have been changed by Caterham.