High Emissions

[timlot]

I have a 91 SE Turbo. In the summer it was difficult to start when hot and was ticking over at nearly 2,000 rpm. Paul Matty had it in and replaced two sensors, it seems somewhat better, but its running very rich and a pre-MOT test showed emissions at 7%. This won't pass and I suspect is not good for the engine either. Its completely standard with only 40,000 miles.
Any ideas on how to get it running properly and reduce the emission levels? I understand from Roy at Matty's that a lot of M100's struggle on emissions levels but surely there must be something to improve it. Its had new plugs, filters and oil last year, timing has been checked and injectors cleaned out.
Thanks, Tim

[GeoffSmith]

See the emissions service bulletin.

[Ian T]

Interesting, doesn't that sound rather like mine Geoff?

If I set my idle bleed screw close to where it should be, my revs go up significantly and it is an absolute whatsit to start when warm. I find I have to start it in anti-flood mode (foot held to floor while cranking) and then it starts unevenly and coughs a lot before running fine on the road.

My theory is that I have unmetered air entering next to one inlet port and that is what is causing my problem, one plug looking lean, the others looking very very rich if left to idle for a while.

Tim - have you looked at your spark plugs? Are they all looking the same colour? I found that mine equalled out a lot after a run, but leave it idling for a while and it soots three of them up more than the other one. Interested to know if yours is behaving similarly...

Ian.

[HJ2]

When you start it while hot.... do you smell the fuel?
I had the same, and after trying everything possible, it was solved when I replaced all injectors. After all these years they corrode a little and one of mine could not completely close anymore when hot.

Keep us posted!

[Ian T]

In my case, cleaning the injectors removed a lot of debris, and seemed to stop the leakage while the engine was turned off, effectively improving cold start. Replacing them didn't materially affect the hot start. Mine starts beautifully from cold now, but floods in the first couple of rotations of the engine when hot and obviously smells bad too.

I'm even considering remoting the fuel pump relay wire to a 'push to break' switch to ease this, as it starts beautifully when the fuel pump is not running (obviously before conking out).

I've been thinking about the memcal - wonder if I can (a) confirm which mine is and (b) get a copy of the right code to put on it (I have an EPROM eraser amd programming gear).

When I had the ECU out, it definitely looked like it had been opened, so this isn't a silly thing to check...

Ian.

[HJ2]

With mine it was the other way around. Cold was always perfect, hot as described per above. Replacing cured it.

Since it starts OK WITHOUT fuel pump running... I still believe the injectors are leaking and you start too rich to even start properly.
Did you check the condition of your Fuel Pressure Regulator?

[Ian T]

I did run the fuel pump and fuel rail with injectors fitted (rail removed from its position) to measure fuel pressure, which (without the engine running) was 3 bar, so while I've not measured the pressure during cranking, I believe the fuel pressure regulator is OK. Cold is now fine, just warm / hot / run in the last few hours that is a problem.

My injectors are new (from RockAuto) and overall pickup when on the road is very good, certainly not in any way feeling like it's hunting. I'm still expecting my inlet gasket or something I can't see around my inlet plenum to be leaking. Hopefully now I'm off work for a couple of weeks I'll have a chance to find out, as this car has been like this for several years (not done very many miles in that time though).

I'm hijacking Tim's thread though, which wasn't my intention. Perhaps some of this discussion is useful?

Ian.

[timlot]

Thanks for all the suggestions and comments guys. I've checked the history file over weekend and the last owner replaced the chip in the ECU -he said " to reduce emissions from more than 5% to between 2-3% " so that appears to have been done. Will continue to think and investigate over Christmas when I have more time. -(busy sorting failed oil boiler controller and leaking shower pump at home -just before Christmas when days are numbered- hey ho!) Tim

[Fourdoorcat]

I hope this doesn't get in the way of you having a very Merry Christmas, Tim.

[Enright]

Holy thread resurrection Batman!

I would advise starting with the basics: check the base timing, check for fault codes, get Elanscan on it from stone cold to when the fans cut in, and post the results here.

Something is definitely wrong - as you say it could well be an air leak from somewhere and I would try to find that by blocking the intake to see if it still runs (it shouldn't). If it does then there's a leak through the intake system which you should be able to trace using a piece of hose as a stethoscope.

If you can get it running properly from the above fault-finding, then the best way of reducing the emissions is to go closed-loop - see here: http://wikilec.9600.org/index.php/Conve ... d_loop_ECU

Please let us know how you get on - the benefit of your experience/s could help the next person to come across the same problem.

[timlot]

Hi, Yes all sorted now. Mark at M100Hoods in Norwich took it on to fully diagnose it. He replaced both coolant and MAT sensors (these were faulty), HT leads, plugs etc and got it down to the correct emission level. It drives fantastically now, completely transformed it. Whilst he had it he sorted the loose steering by fitting a recon/exchange steering rack, it now drives as it should. Exhaust had small holes in silencer so fitted Cybox SS as well so it now sounds like a sports car (much better).
Overall the service from Mark was great, well worth his time & effort as its now great fun to drive and own yet again.
Tim

[nhaynes]

I have a 1992 Elan SE (no CAT open loop) which has failed its MOT emission test due to CO being above 4% (versus 3.5% max).

I'd appreciate some help as I've already completed some preliminary adjustments: I've adjusted the C0 pot, the small blue box adjacent to the ECU, whilst being hooked up to the MOT exhaust gas monitor. I did this with a paperclip in the A and B ports of the ALDL so the car was in CO adjust mode as per the Lotus Service Notes and WikiLEC. Adjusting the pot screw made no difference to the CO values. They went up in one direction but would not come down below 4%. Is this due to being at the end of the potentiometer range? I checked the ECU and it still has the original Lotus seal in tact. I'm loathed to break the seal to change the CO PROM but maybe this is the only way to get the CO down? I'm running fairly old spark plugs and air cleaner, last change 4,000 miles/3 years ago so should probably check these. Any other ideas would be greatly appreciated.

[theelanman]

unfortunately the co pot is very long and the adjustment is in a very tiny section of that very long screw...
it took me ages to do sort it.......2 days IIRC....about 3 attempts........and lots of patience

[Fredjohn]

A trick/process I read in the WSM.

After adjusting the Pot, and before going for an MOT, let the engine warm up enough to bring the fans on, then off, ie 1 complete on/off cycle.

The CO2 reading should be lower after this process. When I first did my MOT 2 years ago the CO2 reading was marginal (3.5/3.6): he pulled the sensor out of the exhaust a bit and it passed Last year I cycled the fans on/off twice then went for the MOT. It passed easily, at 3.1 IIRC. I had made no other changes to the car at all.

See Engine Management Manual Section EMK.3 - E on Page 6 of that section.

[Enright]

You must make sure base timing is right before messing about with anything else.
Also a failing Coolant Temp Sensor can cause over-fuelling.
Elanscan will tell you if you have the ECU with the upgraded PROM code which I believe alters the sensitivity range of the CO potentiometer, but you need to rule out the other stuff first.

[nhaynes]

Thanks for those that have so far replied. I've gone and checked stuff I've done since the last MOT. All plugs are ok with 0.031" gaps. Air filter still looks new. Oil level was too high, over the max fill mark. I've removed 0.7L. I do wonder if this was pulling through the crankcase breather system and contaminating the exhaust gas. I can check again on the MOT tester and see if it's made any difference. I did change the coolant last year and noticed a change on the temp gauge but can't believe this is the cause. I'm also now running on a full tank of new fuel. I'd be interested to know if anyone else has adjusted the CO pot and whether adjustment one way (anticlockwise) reduces CO and the other (clockwise) increases CO or whether there is a sweet spot and lots of spare travel. If the latter I have lost the original setting so will need to find the sweet spot again. If I adjust without the exhaust tester, would you expect to hear a change in engine note when yo find the sweet spot for CO on the potentiometer?

[180mph]

Hi.

I had same problem with mine. The car had not been used for quite a while before I bought it and very little use over the last 7 years.
The injectors where squirting fuel in every direction badly and not closing when they where switching on and off.
This will make the CO high and slowly fill the sump with petrol. mine had almost 7 litres of oil mixed with petrol in it when I drained it.
They are simple to take out and test. Have a look on youtube.
Be careful with the plug clips as they are very easy to lose.

I got a set of new injectors from Rockauto in America they are the same as Isuzu impulse turbo ULTRA-POWER MFI559.

They had them on ebay the week before I bought them at an amazing price. I missed out on that price but worth looking.

I have a new rockauto discount code if anyone would like to use it 3175513729053213 expires July 19th 2015
If I buy anything from Rockauto now, I remove pay import duty from their tick box and use the option for USPS mail and never get asked to pay the import duty when they are delivered.

Good luck.

[Tuga2112]

If I buy anything from Rockauto now, I remove pay import duty from their tick box and use the option for USPS mail and never get asked to pay the import duty when they are delivered.

just to point out 180pmh is in France, it appears the french customs are a lot nicer to their population than the British ones. (i feel tempted to start another rant as to why pay VAT on products from outside the EU when VAT is an EU imposed tax....)

as for the high CO2

Mine failed for that reason (together with another 8.) after fixing a hole in the exhaust the reading gone from over 8% to 1.8%, it may be worth checking if you got some minor leak in your exhaust ?

[nhaynes]

It's been a while since I posted and only just got around to getting my Elan on the exhaust gas analyser again. The results I got are:
CO: 5.04%
Lambda: 0.899
CO2: 11.1%
HC: 150ppm
O2: 1.12
I'm thinking the engine should be running at stoic (Lambda=1) so Lambda = 0.899 certainly proves I'm running rich or don't have enough air. It still starts poorly when hot but first crank when cold.
I changed the cam belt back in May 2013 and thought I'd got the base timing spot on but now I'm questioning whether I should re-check. I don't have an emission reading for the MOT last year so maybe it was missed after the belt change.
I've tried all the simple stuff so base timing, injectors or coolant temp sensor are now in the frame. Any other ideas would be gratefully received.