I may have a problem with my ECU and as I can’t find anything wrong with the loom, I was wondering if anybody has a spare 190 ECU lying about that I could borrow/rent/buy?
Any leads appreciated!
Does anyone know the difference between the 340r 190 ECU and the Exige 190 ECU? They have different part numbers, so guessing there is a difference?
I’m not sure there’s any real difference. The one on my Exige even had a 340R sticker on it 
When mine developed a fault, I borrowed the one off pmyhill 's actual 340R to test and it worked perfectly, so they’re certainly interchangeable 
Out of interest, what’s the fault with yours? I never got to the bottom of my issue - I was stuck with various fault codes and 5500rpm rev limit - so have swapped to an Emerald.
The 5500 rpm rev limit is usually the wheel sensor that feeds into the ECU. My problem is that after driving for 20 mins, the ECU battery fuse (B2) blows intermittently; it only supplies the ECU and OBD port, and all the wiring seems good, so I suspect a problem inside the ECU.
The part number on the front of your photo suggest that it is a standard 177 bhp ECU, is that right? The wiring is slightly different between 340r and Exige, but it looks like a 340r ECU would work ok in an Exige. One thing of interest is that it mentions in the 340r section of the manual that the 190 is ‘open loop’; wonder if this means that it never runs in closed loop mode? Would certainly explain why it runs ridiculously rich at idle!
An Emerald has crossed my mind, but it’s 375 miles away and the logistics of getting there and back would be a pain.
I’m fairly sure the 340R and Exige ECU’s are the same unit.
@deggles - you’re lucky you have a part number sticker, quite a lot don’t but at least you have “190” written on in the official blue marker pen!
I have a 190 ECU here (well it was sold to me as a 190 by someone on here, as I recall) that doesn’t even have that…just scratched on! Next time the car comes up for cambelt change that’s going on with the replacement pulley. Unfortunately there’s no physical way to spot the difference - various stories from way back about 190’s having a yellow dot on an ic, but never anything definitive.
@C8LGY - I’d suspect the OBD port, maybe moisture/dirt somewhere in a crevice that’s causing a short? My company works on laboratory instrumentation and it’s remarkable how a short can occur without even the slightest visible signs. Generally a good spray with an oil-free electronics cleaner - we use IPA*- and plenty of airflow does the trick. Worst thing is warmth, as all that does is drive any moisture further in rather than out!
(* IPA = isopropyl alcohol, not India Pale Ale!)
Yeah I’ve measured the OBD port resistances, as well as cleaning them out with contact cleaner - everything seems good! I’ve now separated the ECU supply from the OBD supply, so that will confirm it.
Yeah mine just has marker scribbled on it too, but I know it’s a 190 map as you can tell from the OBD port with the car running - the fan cuts in at 92C on the 190 map.
Spoke to Lotus dealer today, and they tell me that A111M0156K (Exige) and A340M600K are the part numbers for the physical ECU. The Exige 190 is based on an exchange, and the number LOTAC05223 is the service charge (£650!) to send it off to their partners (presumably EFi) to map. They can send off ECUs for inspect/repair, but you’ll get charged £650 whether they can fix it or not….
Ouch! 
£650 is punchy with no guarantee of a fix! Back in 2018 I sent mine to ECUTesting, unfortunately they weren’t able to fix or diagnose it but didn’t charge me anything.
I saw more recently that Esprit Engineering have started offering repairs on the V8 Esprit ECU which is the same physical unit as the Exige (different config obviously), could be worth a call?
@C8LGY - I had a vague recollection the EXIGE 190 ECU was on an exchange basis so thanks for confirming that I wasn’t imagining it!
Splitting the ECU and OBD supplies is definitely a good test and, hopefully, should identify if the cause is one or the other. Best to run tests with your ECU, initially at least, to avoid throwing in another variable.
If you do find one, make sure ‘190’ is written on it in crayon, otherwise it may be fake
Craig,
I have a spare 177 ECU if that helps?
R
Cheers Rich, I’ve actually bought a second hand 190 to test, so should be able to sort it somehow. Wonder if it will run ok with the advanced inlet timing? Probably!
Yep, will be checking it’s a 190 with the OBD, luckily it looks like a kid has been let loose with a felt tip pen, so decent chance of it being real! 
Hi -my ECU may be faulty as I am at loss with an unknown limp mode. Any chance I could borrow yours?
For info, Lotus can’t supply them anymore, and the 3rd party they were using for repair have went into administration due to covid. However, Espirit Engineering can potentially check/fix them, and I believe they may have an Exige ecu in stock too. [email protected] if you’re interested.
Thanks, I’ll give it a try
Just back on the forum so only seeing this message now - PM me and we can try and sort something out.
Thanks I think I may have found an Emerald!
Remember to reverse the fuel relay wiring!!
I hope the tuner will remember that. I thought I found an emerald but it is a K3 and not a K6. The tuner is telling me that I need a k6 and not a K3. So I am back looking.
Why do you want an Emerald? Are you still concerned your ECU isn’t working properly or more for tuning /optimising the running?
Strictly for tuning / optimizing it running.
I don’t think stock ECU can be flashed so I am looking for an Emerald.