I appreciate this is a very generic description and could be any number of things. But… bear with me.
After fitting the replacement backbox I went for a spirited drive around the block (after warming engine up of course) when I rolled in and down the drive it just cut out. Started again but after a few turnovers. Left it idling and it did it again a couple of times.
Checked odb and nothing logged.
Not having much luck with cars at the moment 
just a quick update as im driving it daily at the mo as daily is knackered.
what happens is when the engines warmed up (temp reading displays on binnacle) driving is normal, as I approach lights with clutch down to stop, the car idles for a few seconds and the rpms drop as expected, go below 1000rpm, continue to fall and it stalls. I can keep it going by blipping the throttle.
It doesn’t do it when I first start the car and leave it running as the idle seems higher.
Any thoughts?
Hi - I don’t know much re series 2 Exige. My S1 had a phase of similar and it was the quality of fuel. Plus just needing a bit of a map update (the VHPD is lumpy at idle anyway) but I’m running an emerald Ecu.
In reality my car needed a couple of tanks of driving/use and all healthy again.
But that’s an S1 and my fault for leaving it in the garage to often.
The higher idle when initially starting will be due to the ECU compensating for the low temp with the electric throttle body.
I do seem to recall that @Fonzey had issues with the 255 map doing the same - stalling out
I recall correctly - 2006 Exige S - #489 by Fonzey
Funny you should say that. I had a similar thought process and banged a tank of vPower in. it does sit around a-lot not doing much so could be that also.
Is the ECU controlling the idle rpm then rather than say an adjustment screw on the throttle body?
There is a IACV on the cable throttle body. I have taken mine apart and cleaned it.
I am not 100% sure on the DBW TB that you have.
If you have electric dbw throttle it’s all controlled by the ECU, but there is also a set screw for the butterfly which theoretically could be used to fool it.
I went through a lot of this with the OE Lotus map, if your car still has the actual 255 map on it then it’s known for being one of the worst that Lotus produced for day to day drivability, and the 260 map was offered as a dealer/warranty upgrade to address them back in the mid 00s. Tbh, even my 260 map was not much better.
I eventually “fixed” this by way of standalone ECU and aftermarket injectors, but then when I came to sell the car I returned it to the original injectors and ECU. The new owner had the injectors tested and found one of them was badly knackered and was just oozing petrol out.
I loaned him the OE injectors out of my 2-Eleven and by all accounts the stalling issues have been entirely resolved.
So if you’re on the 255 map, see if you can source a 260 one as a first port of call (buying a used ECU probably easiest as I don’t believe dealers do reflashes anymore).
Second to that, consider getting your fueling tested. A wideband sniffer in the tailpipe may give some unobtrusive data, but a proper injector test shouldn’t be too expensive if you want to rule that out.
Thanks for the detailed response @Fonzey. I have no reason to believe it’s not on the 255 map. And don’t know how to check anyway. Being a new issue (though it did do this very occasionally) it’s perhaps more likely I have some other issue than the map?
That said, it’s also started happening since I changed the back box… at the same time backed the o2 sensors out of the exhaust flow with some spaces as the cat pipe is just a dcat now. Not sure if the issue is related or just coincidental?
Too many variables now.
Perhaps worth going backwards and setting to your last known good?
Well it was decat before, I just didn’t know the cat was in the back box. EML would come one so that’s why I backed off the sensors.
Appreciate what you’re saying though.