High CO and MOT fail M100SE 1991

[chrism]

That's good news!
When you 'go 1499' expect fewer worries with MoT/emissions and much better fuel economy...

[RonR]

Rich, You have mail....

[Richmmm]

Just a quick update about my car.....I fitted one of Ron's MEMCAL adapter PCBs, which are loaded with 9930 and 1499 programs. I also fitted an O2 sensor. It is currently running 9930.

The car sailed through the emissions test for the MOT today, the CO level was down to 1% from 6% with the old 9929 PROM. i will try 1499 in the next few days.

So relived the car got through the MOT!

Rich

[chrism]

Yep me too - except I jumped to Ron's 'full fat' 1499 option from my original 'dinosaur' 9239 MEMCAL'd SE

_DSF0349a.jpg

Over-fuelling open loop 14:1, ~25mpg, smelly + sooty exhaust...all those things have paled to become closed loop 14.7:1, ~38mpg-around-town-and-late-40s-on-a-run, closed loop.

I had to get a 'sparky' to finish off the incomplete wiring - and that turbo plug was a real battle - but it's been the best of upgrades that has taken away all my MoT emission fears . There's absolutely no performance loss, either.

If you've got an SE with the later loom (I gather many have...) I reckon Ron's dual pcb plus an O2 sensor is a no-brainer!

(ps I'm not convinced the 9930 MEMCAL should recognise your O2 sensor(?) - but with the jumper switch in place (it's the little black bit in the middle of my pic) I'm certain the 1499 option will...)

[Tuga2112]

where can i find details about this pcb you mention ?

i been pondering about getting a mountain chip for years, and right now im 90% convinced on getting one, BUT ive seen written somewhere you cant get them anymore... im a bit at a loss.

[chrism]

Hi Tuga2112, I'm a newbie and was disappointingly late to the Mountain Chips party...

I'm really hoping there'll be a 'Son of Mountain Chips' or a Part II revival so's I can get a fix too...

[chrism]

Tuga, read RonR's post on p2 of this thread. He developed the dual pcb

[Tuga2112]

Over-fuelling open loop 14:1, ~25mpg, smelly + sooty exhaust...all those things have paled to become closed loop 14.7:1, ~38mpg-around-town-and-late-40s-on-a-run, closed loop.

i used to get 36mpg around town open loop. and 40 on a very good run.

after doing the head gasket and resetting the timing to "factory standard" 16 ahead of TDC its done 32 around town and 38 on long runs.

its a considerable differencw you got. but it seems to me i will be trying to adjust my timing for now and hopefully soon Ron will have an upgrade version of he's PCB instead.

[chrism]

an update on SE 1499 conversion:-

9239 prom id 2022 MoT results - open loop (pre RonR dual pcb):- CO% - max 3500 actual 2.499 Pass
HC - max 1200 actual 183 Pass


1499 prom id 2023 MoT results - now closed loop (post RonR) CO% - max 3500 actual 0.78 Pass
HC - max 1200 actual 143 Pass

So, opting for that O2 sensor conversion with Ron's dual board has lowered emissions as well as increased fuel economy and reduced MoT 'non-cat vehicle check failure anxiety'...

Hope this helps by adding actual figures...

[Fredjohn]

Chris
Very similar to the results I got after going closed loop.

Good to hear the new board works with the 1499.

[HJ2]

Good stuff indeed!

[Hector2021]

I may be being a bit numb here but i was under the impression that it was the S2 cars that had tighter emissions specs so were more prone to failing at MOT time.
This is why my original Elan hunt was for an SE. I only really ended up with an S2 by good fortune.
I have noticed that sometimes mine does smell like an alcoholic after a good sesh, so assume it may be running rich. Even a mate of mine who doesnt know the difference between a screwdriver and a spanner made the observation. My MOT isnt due until early April so i guess i wont know its output for sure until closer to that time.

[Fredjohn]

I may be being a bit numb here but i was under the impression that it was the S2 cars that had tighter emissions specs so were more prone to failing at MOT time.
This is why my original Elan hunt was for an SE. I only really ended up with an S2 by good fortune.
I have noticed that sometimes mine does smell like an alcoholic after a good sesh, so assume it may be running rich. Even a mate of mine who doesnt know the difference between a screwdriver and a spanner made the observation. My MOT isnt due until early April so i guess i wont know its output for sure until closer to that time.

Although the emissions requirements to pass the MOT are stricter for the S2, it is less likely to fail because it has closed loop and a cat.
Hence many SE owners have gone closed loop. Above quoted figures are typical of the improvemt of converting from open to closed loop.

[chrism]

Hi Hector2021. I hope this 'history' adds 'flesh' to Fredjohn's explanation. Yes, you're right S2 has tighter emission specs.

Non-O2 sensored , non-cat SE has 'open loop' fuel to air mix which needs manual adjustment and, later I believe, a component upgrade to 'get it right'. In the late 80s emissions were only just starting to become important. Petrol was cheap and cars that ran 'rich' went faster...

S2 has 'closed loop' fuel to air management continually adjusted by the ecu to always hit the sweet spot (I believe 1:14.7) - improving emissions and fuel economy etc. S2 emissions are regulated by an O2 sensor and further improved using a CAT - just like modern cars - although the CAT apparently 'saps' ~10bhp from the S2 which isn't entirely popular (but needs must...) and S2 has a different (modern) MoT testing regime as a result.

At PROM id 9239 my '90 SE was an original example. SE ecu chip upgrades were 9239 -> 9929 -> 9930 for open loop. 1499 was the new S2 closed loop upgrade. Many SEs have all the S2 O2 sensor wiring and those that haven't need a couple of wires added to the loom so as to attach an O2 sensor. The sensor position in the SE is blanked off but 'easily'* recoverable and it's in the same place as that used in the S2.

RonR recently manufactured a dual-board 'chip addition' that easily plugs inside the SE ecu that can run 9930 or 1499 for SE owners just by changing a 'jumper'. S2 owners simply have the 1499 enhancement in their ecu.

So early SE owners can now have improved 9930 non-O2 fuelling - and all SE-ers can also add an O2 sensor for (even better) 1499 fuelling and lack of MOT emission worry. We're not required to add the CAT - and enjoy that 10bhp 'penalty' as an unexpected bonus...

I hope you get your S2 'sorted' and the MoT man looks favourably towards you in April.


* as easy as it is to remove a 30+year-old bolt that's been baked in a turbo...

[Hector2021]

Many thanks Fredjohn and Chrism. That makes a lot of sense of the ooen/closed loop discussions and also of the references to the ecu upgrades.
Learning a bit more about my car every time i visit this forum

[chrism]

Hector2021 we are all we have. I've been around LEC for a year and I've found that most of the questions have been asked and answered (and the dust settled..), and many of the answers are somewhere not very obvious at first sight.

M100 ownership has been a huge learning curve for me. I came from another car club where d-i-y servicing/repair was 'at the garage' and now I find the skills of intrepid LEC-ers make me feel like I'm back at school - they're so good.

Don't be afraid to ask; people on LEC are mostly nice... and no question is 'silly'...

Loadsa luck.

[Hector2021]

Thanks Chris,
Wise words and have to agree to the huge value of this forum. I have joined the M100 party quite late and i suppose as a result pretty much every problem or issue that is ever likely to be encountered already has by now, and with some excellent advice on how to get around it. The obvious worry at being a latecomer seems to be the frightening price of parts that are either no longer supported or made rare by the same result. A lot of older cars now out of print tend to still have a good support network behind them, usually due to their larger production run and popularity. I wish the M100 had been one of those.
I also migrated here from an earlier classic car having owned up until late last year two Triumph Spitfires, one of which i did a raft of restoration work on in the nine years i owned and loved it. The various Triumph forums, FB groups and meetings with equally enthusiastic and non judgemental owners proved invaluable again.
Eventually though the M100 itch needed scratching and after a couple of years debate about leaving simple mechanicals and electrics behind in favour of more complication but more performance, here i am.
Potential costs and worry aside, im happy to report that i am loving it though. Currently working my way through some minor niggles and so looking forward to the better weather days. I am of course yet to find out the pitfalls of my first MOT with a tester who possibly doesnt understand the nuances of these cars (rear wheel bearings as an example)

[chrism]

Yes m100 is a step -up in 'wrangling' over anything MG/Triumph. We don't have such good/easy parts availability; cor if only Rimmers did Lotus...

re cost of spares. I'm a very recent convert to RockAuto (it only took a year ) since many engine parts (inc rear calipers + pads) are a fraction of UK prices. Check out their w/site; my cambelt/tensioner/idler delivery (~£80 from US!) was on Mon after a Thurs order!

Engine parts are Isuzu Impulse 1.6 and rear calipers are Oldsmobile Cutlas - I'd imagine other US GM/Chevy bits too.

Front discs + pads are UK GM from the likes of Carparts4less/EuroCarparts in UK who often have 50% sales. In May '22 I got a pair of front discs + pads - both Pagid - for £26.92 inc vat + del and in Jan '22 I got Crosland oil + air filters + 4 Bosch plugs + 4l Magnatech 10/40 A3/B4 all for £33.61 inc vat + del. I'm not being 'smug' (that comes after you've got parts and fixed something ) but I'm just spotting opportunities not to pay phenomenal 'Lotus' prices for the same good stuff...

Yep, I was deffo spoiled for parts in the other club (I'm still a member, I blu-tack coloured cardboard MG badges over Lotus when we meet) and I wondered why I defected, but LEC help has poured oil over troubled waters.

(Talking of oil just wait 'til you do your first oil + filter change! My second will be so much] better... )

[Tuga2112]

oil filter change is easy.

just accept the fact that the subframe HAS to come out, and 20 minutes later the subframe WILL be out.

if you done Geoff's trick by putting your hand behind the engine before, its quicker that way, but you may find the previous person torque tightening that will make your life hell.

subframe removal is a 20 minute job, the access to the oil filter is completely trivial after that.

this one will be available on saturday.

im now off to record the video of changing the thermostat

[nicowalker1]

Update:

The O2 sensor arrived yesterday so I had all the hardware to jump straight from promid 9239 into 1499 closed loop.

Today the mobile electrician came and managed to crack off that dratted turbo bung before trying to work his way through the wiki advice to replace those missing wires. He 'did his own thing' which was similar but found some discrepancies, either with my car or wiki (which added to the process time, hence cost...)

I've taken loadsa pics to flesh out wiki's advice - esp with finding the O2 sensor m/plug and disconnecting the ecu plugs

After checking continuity we fired her up and the car wavered up + down a bit on initial tickover as (perhaps) the iacv valve self-adjusted.

A couple of hours later when I'd replaced binnacle, arch liner etc I started up again and ran the car straight into the garage. I noticed that the idle had reverted to ~1000rpm (still cold) and was absolutely as stable as before - so all seems well so far...

Next course of action is to hook up Elanscan, see if it identifies 1499 and (Ron suggested to) check that the O2 sensor vs time shows a wavy readout inferring that the 'closed loop' process is properly happening to monitor/control the mixture level...

Thanks everyone for all that extremely useful advice, support + encouragement; it's a bit complex for a 'newbie' - but ultimately very do-able

Hi Chris, any chance you could share these pics?