High CO and MOT fail M100SE 1991

[chrism]

Thanks Chas54, that info adds flesh to the bones and is helping to build up a picture

In fact the more I read wiki the more I feel that getting the 2 wires in place is do-able but the splicing bit is causing a bit of anxiety particularly if there are terminals missing. If they're not I presume that there are 'scotch-lock' types of connectors to simply lay the wires side-by-side and snap the connector - or will I need something more sophisticated?

Ooh for a video from 'someone in the know' showing a blow-by-blow account...

[Twayblade]

Many thanks to all for the input, offers of help and guidance.
Here's an update to my original post-
Blaster leant me his spare ECM which had a 9930 memcal and a Gunson CO tester, this enabled me to adjust down the CO reading ( from 5%) to 1.7% and pass the MOT retest on the second attempt.
I have now re installed my original ECM with Ron's selectable dual image 9930/1499 pcb, as described by Ron previously ( I may well go closed loop in the near future) double checked the CO% reading which did not need any adjustment and I'm now looking forward to getting out and performing some on the road Beta testing!
Wishing all an enjoyable Easter break, and once again thanks for the brilliant support.
T

[chrism]

Yes imo on further reflection that seems an ideal way to go forward with Ron's dual 9930/1499 pcb.

I'm coming from a 9239 w/out the extra wiring, it seems, and (to me) it's a bit of a 'mission' to add this, install the pcb and 'wrangle' the 32year-old turbo plug out of it's rusty haven.

The pleasing thing about Ron's initiative is that the big step can be reduced to easier stages - as opportunity progresses - and the looming MoT worry surely becomes a thing of the past.

And yes, an eventual increase in mpg and closed-loop CO control with the 1499 application becomes a welcome reality for SE owners. It's especially good to have this back again for those who missed it first time around.

[Chas54]

Chris.
I was convinced i didn't have the full wiring when i went to the closed loop. I had the dashboard in bits looking for the connection to the alternator field bulb for the 12v supply , i also couldn't trace the wiring back to the ECM plug for the O2 return signal. I had a Clifford alarm and immobilser that would trigger every time i tried a reset on the learnt setting by battery disconnection. During the course of pulling the immobiliser out i came across so many scotch lock connections that were poorly made , i threw the lot away , and the Clifford.
But the wiring for the O2 sensor was intact. When i plugged up the new ECM from de roure, i could then trace it all.
So i didnt have to splice in to the 12v system for the O2 sensor heater supply.

If you haven't got a copy of the ECM manual for the electronic MPFI closed loop , you should down load it .

It has loads of great information on fault codes and troubleshooting . The sensor wiring diagrams are excellent.

Also EMJ4 section has the ECM connector identifier chart... It shows the two plugs and the expected value and source of each populated terminal.
Looking at my copy i think plug J2 terminal D7 is the O2 sensor signal voltage (ie the return voltage from the O2 sensor) whilst it may state 320 to 450 as the voltage with the key on engine not running, i think its actually 0.3 . Hot running engine varies to about 0.6 or at least thats what i measured when playing with mine.

I note you are using elanscan , can i recommend a dapinky switch ?
Mr dapinky has a post on here that explains the use of a switch on your elanscan cable to apply the service mode short. This would allow you to observe your elanscan data live whilst in the service mode. I found this really usefull.

My O2 sensor came from rock auto. Despite being in the US , they keep some stuff in the UK so it arrived pretty quick.
Removing the O2 sensor plug is still the most challenging thing. Mine i heated with a small oxy acetlyene set i have and cooled it with ice after soaking it release oil for days . I have a long breaker bar for 1/2" drive sockets and i eventually bit the bullet . I think the worst case would be damaging the turbo housing. I think the thread may be 18mm.
charlie

[chrism]

A fantastic post Chas full of specifics, thanks for that.

Pessimistically for me I gather that the earlier SEs (mine's a Dec'90 9239) had the incomplete wiring and your '91 SE must be one of the later ones c/w intact wiring. On mine there's no heater brown/yellow -> earth/black continuity as expected from the engine bay m/plug - which seems to infer that at least one of the wires must be missing; in all probability, both.

Yep I'm gearing up to be brutal with that bung when it's time...I'll look up that Dapinky switch info too, thanks.

(Grateful thanks to all, I'm learning so much in such a short while )

[chrism]

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

[Chas54]

Chrism
I was checking mine a couple of day ago as my Win7 notebook had lost its communication with elanscan - turned out the com port wasn't selected to 5 for some reason. Maybe an update or something .
Anyhow i checked my combustion etc and if you look at your trace of CO potentiometer/ Oxygen sensor , it should vary rapidly between 0.3 to 4 volts approx. Or at least mine does and it was running well.
The CO potentiometer (blue pot by the ECU) is redundant and i took mine off. Although if you leave it in place it wont make any difference.

Remember the Idle Air Control valve needs to have its correct position re learned . Normal advice is a run at constant speed around 30mph for a few minutes.

When i had my intake plenuum off i had a good look at the idle air control , and it works my bleeding air past the throttle butterfly valve. As such it is of course only in operation when idling.

I hope you get there, mine is a different car now its running well. My final revelation in my journey was changing the petrol. Make sure you have some good quality E5 .

Charlie

[dapinky]

ChrisM,

without stating the obvious, but remember that the 1499 runs a 'closed loop' map until the engine is up to temperature anyway, so the ECU will take some time to adjust itself to the new set of readings (as you posted - no worries with that happening).

You may not get any (or at least, inaccurate) O2 readings on elanscan until you get a temperature cycle above it's threshold. I'd run elanscan from cold, up to the fans kicking in, and then you can check where the thermostat opens, where the fans actually kick in, and where it goes into 'closed loop' mode..... all for no reason other than the knowledge of what happens, when it happens, and that the gauge for temperature doesn't look right!!!

[chrism]

Thanks Chas54 and dapinky for bolstering the info
Yes I was expecting a period of adjustment or settling-in, usually around 200 miles or so in my MG experience.

[Richmmm]

My car was registered in Feb 1992, so hopefully it has the cables in the loom to upgrade to closed loop. From previous posts, hopefully someone can confirm that the connector in the photo are the correct one.

One connector has three wires, The other free connector has only two wires. Could anyone tell me what this connector is for?

Rich

[Fredjohn]

Can't tell from the photo what the wire colours are.

However, if you can identify those colours you should be able to identify the connectors from the wiring diagram in the Manuals section above when signed in.

[chrism]

_DSF0309a.jpg

Hi Rich. Mine's a Dec '90 SE (previously) w/out a complete loom .This black 3 wire black/brown-yellow/grey-green is the connector that I needed to connect my new O2 sensor to - and you can just manage to make out the brown-yellow + grey-green wires on your pic; the black wire is well-camouflaged by your paintwork . I didn't feel the need to find out anything about that other grey m/plug connector at the time, though...

I'd be very surprised if your Feb '92 Elan didn't have the complete loom already. I'd have normally thought that with this reg date, yours must either be one of the very last SEs or an early S2 (which would already have been 1499'd c/w O2 sensor and cat fitted...)

Out of interest:- 1. I presume you've ElanScanned your ecu to verify your current promid? (I'd imagine 9929/9930...)
and 2. have you already '1499'd' your ecu? (- or where will you get the memcal upgrade from?)

Finally, imo you'll be glad you 'bit the bullet'. Upgrading to closed loop has vastly improved my fuel cons (easily 35mpg local + ~45 on a run with a light foot) and freed me from impending emission worries around MoT time.

Let us know how it goes. I took loadsa pics and would be more than happy to share them, if it helps. (You're not alone and don't forget to soak that O2/turbo blank for a week or two, get access to a long breaker bar ) and a pal to hold the socket down as you strain to break the infamous 'welded rust bond'. Previous heating, then dousing it with ice has been suggested too...)

dur...I've just found your earlier post where you wanted to upgrade from 9929 to 9930 and presume that you've decided to 'step further' to 1499. RonR was a major source of motivation and inspiration along with valuable input from other 'stars'. Without that much-needed advice and encouragement mine definitely wouldn't have happened!

[Richmmm]

Yes, the colours on that connector are Black, Brown / yellow and Slate / Green.

I have found the diagram and the colours agree.

The black cable is ground (0R to the engine block) but the other cables only have a few hundred millivolts on them. I would expect to measure 12V on one of the others and maybe a 5V pull up on the signal cable. I will trace the cables later.

The ECU has a 9929 label, which is also shown on elanscan. I have a 9930 EPROM which I am going to try before I go closed loop.

Thanks to all who helped. Rich

[chris]

I popped into SJ Sportscars today as I was in the area and he tells me Lotus only have 4 of the 9930's left. It's no longer a returnable item so I ordered one for delivery in a few days time (£70 ish).

[KenS]

Rich, the Brown/Yellow wire to the O2 sensor is the O2 heater voltage that comes from a splice connection to the alternator 'no charge' light. So with the ignition on but engine not running, the voltage on the B/Y will be near 0V (and the 'no charge' light on). With the engine running, the voltage on the B/Y will be 13 to 14V (and the 'no charge' light will be off). The idea is that the O2 sensor is only heated when the engine is running and the alternator no charge output provides that function.

[Richmmm]

oh Great....that is good news.

I have taken the ECU out today and belled out the wire from the O2 sensor input on the ECU out to the under bonnet plug. The connection is there. I will check the 12V power when I get the ECU back in tomorrow.

Tnx Rich

[chrism]

Aw...sorry folks I was under the impression that all S2 had O2 sensors, cats + 1499 promid...obviously wrong

[Fredjohn]

Aw...sorry folks I was under the impression that all S2 had O2 sensors, cats + 1499 promid...obviously wrong

Er......all S2 do have those bits.

[chrism]

'Senior moment time'...sorry, '92 reg continued to conjure up a fixed pic of an S2 in my brain...but, of course, 9929 promid would indicate otherwise.
Oh, and when he added the extra wiring to mine (Dec '90 reg), my electrician pal was also initially confused by such a low brown/yellow voltage (couple of mV) on the heater wire (ign off) - so KenS's excellent post explains all.

[Richmmm]

I have put the ECU back in the car and it started fine. At the O2 sensor socket under the bonnet, I measured the voltage on the power cable....it came up to 12-14V when the engine was running, so my car has all the cabling installed to convert to closed loop. It is 1992 reg. All I need now is a 1499 memcal and an O2 sensor.
Rich