High CO / Poor hot starting

[Steve A]

Thanks for your help and suggestions John and Simon

[Simon_P]

Hi John,
Lotus spec. is 1.8 to 2.2 ohms. Outside that is rejected.
So 2.5 is a 12% to 30% error depending on how you look at it.

They are always in parallel so the effect is always 100%

[Steve A]

As suggested I have reset the ECU.
I was going to set the base timing but discovered my strobe light leads are to short so I need to make up some extensions
I then went for a spirited drive and then rechecked the plugs (the gap is 0.8 ).
The pronounced popping has now gone and the car seems to be running smoother.
I could check the mixture at my local garage.
Time will tell whether the hot starting problem has gone or if it would be beneficial to go closed loop?

[lotustonybassplayer]

I have recently gone closed loop with a mountain chip, and i am getting at least 5 more mpg, and no longer do i get the smell of fumes as i drive along in the car nor do i smell of them either after a journey and only .5% co at mot time

[Steve A]

I have recently gone closed loop with a mountain chip, and i am getting at least 5 more mpg, and no longer do i get the smell of fumes as i drive along in the car nor do i smell of them either after a journey and only .5% co at mot time

That's good to know, my wife always say's my car sticks the house out when I put it in the garage
Where did you get all the parts numbers etc, wiki?

[lotustonybassplayer]

Yep used the bosch sensor as listed on the wiki. got it from rockauto. I used loads of penetrating fluid over a couple of weeks before I attempted to remove the bung.

[Danny R]

This all sounds remarkably like an issue I've been having. It's always had an intermittent misfire, I've changed the plugs, the previous owner had replaced the coil packs and leads but it still does it. I just shut it off, give it 10 minutes and it'd be alright next restart.
Recently, after a bit of a lay-up, when I start it the exhaust fumes stink, if you spend any time near it on tick-over you go back in the house stinking and there's still the misfire which now comes and goes during running. Seems to be alright when it's up to temperature though.
It's ready for the MOT now, sorting a few issues that'd prevent it passing (Hazard Warning lights, PAS pipe, sidelight bulbs etc) but I can't see it passing the emissions test like this.

Now I know where to start, good post!

[Steve A]

I had my MOT yesterday
viewtopic.php?f=44&t=26393&start=20

[HJ2]

[peteoddcar]

Hi all, apologies for starting another thread but my prior posting seems to have been amalgamated with others and now the original issue is somewhat jumbled with others. I'll summarise my last 3 postings followed by latest info. If anyone has any recommendations, as ever, I would welcome them.

I have a 1992 Elan SE (no CAT, open loop) which has high CO above 4% (versus 3.5% max). Also, starting when hot is tricky and normally requires several seconds to fire. Starting from cold is very good normally firing within a second. The exhaust smells rich.

I'd appreciate some help as I've already completed some preliminary adjustments: I've adjusted the CO pot, the small blue box adjacent to the Engine Control Unit (ECU), whilst being hooked up to the MOT exhaust gas analyser. 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 CO 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.



Hi Neil
You sent me a PM a week or so back about problems with your car - I did reply but always get a bounce back from the email I even tried your email listed in here directly but still no go. PM me is you still need my help
Pete

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 you find the sweet spot for CO on the potentiometer?

Got the Elan back on the exhaust gas analyser again, no significant difference since last time. 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 need to get or borrow a strobe timing light before I can check the base timing again. I've tried all the simple stuff so base timing, injectors or coolant temp sensor are now in the frame.

I've tried disconnecting the Coolant Temperature Sensor (CTS), not to be confused with the fan thermal switch and the temperature gauge sender which are all located on the same aluminium cooling housing. If the CTS is malfunctioning, it may be causing incorrect air fuel ratio (AFR). The CTS is a negative thermistor so at high temperature reads low resistance and at low temperature reads high resistance. Disconnecting the CTS tells the ECU that the resistance is high thereby implying a cold start. Unfortunately the CTS connector is right under the Cam Angle Sensor (CAS) so tricky to remove. Do I need a special tool to unclip the CTS connector? I don't want to break the connector!

I've now run the car at idle for 30 mins (not in service mode) and then removed and checked the spark plugs:
Cylinder 1: Heavy soot
Cylinder 2: No deposits
Cylinder 3: Heavy soot
Cylinder 4: No deposits
Now wondering whether I have leaking/faulty injectors on cylinders 1 and 3 or whether there's a fault with the injector driver circuit. The injectors are driven from the ECU, injectors 1 and 3 on one circuit and 2 and 4 on another. Not sure how to test the circuit.

Sorry for the wordy posting, replies to my questions above would be greatly appreciated.