S1 Project car - part 2 - the continuation

[Lotusfab]

Well just spent a while in the dark trying to get the mixture correct. Have found it impossible to get anything other than blue! When the cylinder misses it goes orange! Have balanced the carbs with a car tune which I have. The tuning seems very erratic! Will see what the gas analyser says. See if I can beat three MoT tests! 

Think mine are about 6.5 turns out?

[jonroberts]

When the cylinder misses (usually due to a lean misfire) then the unburned petrol remaining in the cylinder ignites with the next charge cycle and burns rich (yellow flame).  Come to Duxford, borrow my analyser and set it properly !

[Paul Coleman]

24 minutes ago, Lotusfab said:

Well just spent a while in the dark trying to get the mixture correct. Have found it impossible to get anything other than blue! When the cylinder misses it goes orange! Have balanced the carbs with a car tune which I have. The tuning seems very erratic! Will see what the gas analyser says. See if I can beat three MoT tests! 

Think mine are about 6.5 turns out?

6.5 turns out sounds as though it should be somewhere near. Those Carb Tunes are not really worth having imho you need a decent gas analyzer like Jon's. I borrowed a £150 Gunson one from somebody to set my Daughter's Mini and it was way out, I set it to 2.5% and when the MOT man checked it it was 5%.

Yes 3 mot tests to beat hahaha

[jonroberts]

6.5 turns may be a little rich for the MoT tester. I found mine were about 1.8% CO and ~500 PPM HC at 5 turns out. I have since richened it up a bit to avoid a low RPM stumble that was annoying me. I maintain you need both a decent CO meter and the CarbTune together to get the best results, but I know of other forum members that do it all by feel.  There's a great Youtube video somewhere of a guy tuning a Ferrari V8 set of carbs (yes, thats 8 carbs to tune and balance together) - and he's doing it all by ear.  One thing to be aware of is that after any adjustment you should wait at least 15s before you see the result - there is a fair lag on the adjustments.

[Lotusfab]

Thanks Jon.

[Paul Coleman]

And make sure the air is balanced to start with.

When you get really good at it, as Jon says, you just need a rubber hose and a screwdriver and you can tune a Miura V12...

I wish hahaha

 

[910Esprit]

There's no way I'd let a guy in white slacks adjust my carbs,   No emission tests required for that car - What a beauty  

[Paul Coleman]

34 minutes ago, 910Esprit said:

There's no way I'd let a guy in white slacks adjust my carbs,   No emission tests required for that car - What a beauty  

Yeah it's good to know that the Mafia didn't really blow it up and dump it over that cliff

[Lotusfab]

Quite impressive! I've just set all my carbs to 5 and then richened them to stop the misfiring. It's all running but who nos what's coming out of the exhaust, it stinks of fuel! Also takes a while to settle back to idle!

If I got some white slacks it might help!

[Lotusfab]

Anyone have any idea why the engine takes time to settle back to idle? 

[Paul Coleman]

Does the throttle lever return back to its stop properly when the engine's not running?

[Lotusfab]

Yep? Just been doing some reading. Found the test requirements.

[Paul Coleman]

No, I think they're also measured at 1,000 rpm.

[Lotusfab]

Yep your right, just edited the above. Do you think misfires caused the high HC readings on your first MOT and when you richened the mixture it reduced the misfires and so passed the test?

[Paul Coleman]

No, my issues were due to the distributor.

When I first set my carbs I used the Colour Tune and set them all to blue. That gave a low CO level but very high HC levels as it was basically spitting raw fuel out the back and as it warmed up the unburnt fuel was igniting in the back box and causing the exhaust to become ridiculously hot.

[910Esprit]

2 hours ago, Lotusfab said:

Anyone have any idea why the engine takes time to settle back to idle? 

Air leaking/bleeding past the throttles, e.g  leaking/worn spindles leaking vac pipe, overtight throttle cable, choke mechanism not closing fully etc.   Probably also happen with significantly unbalanced throttle butterfies.   I would start with a manometer  that can do 4 pots at the same time. Does exactly the same as the cat in the white slacks, except more accurately....   I'll put a 2p on mine tomorrow and see if I out trump his 1 coin....  

Edited April 24, 2016 by 910Esprit

[jonroberts]

1 hour ago, Lotusfab said:

Do you think misfires caused the high HC readings on your first MOT and when you richened the mixture it reduced the misfires and so passed the test?

Yes, thats correct. Running too lean (indicated by low, or very low, CO readings) will increase the HC emissions as the fuel is not combusting completely. High HC = raw fuel out the tailpipe.

Richening up the mixture will raise the CO and reduce the HC. Theres a point at which too rich again causes the HC to increase. It's all a balancing act - lowest CO and HC with the highest CO2 you can obtain (but you need a 4 gas analyzer to measure O2 and CO2).  There's a good writeup with a useful chart on it here :

http://www.crypton.co.za/Tto%20know/Emissions/exhaust%20emissions.html

 

[Lotusfab]

Managed to get hold of a gas analyser. Some remarkable readings CO 2.8, HC125 PPM, oxygen10.4!!!! Has anyone else has an oxygen reading this high. Could of course be the tester probe no long enough!

[jonroberts]

Perfectly acceptable for an easy MoT pass.  What was the CO2 reading ?

[Lotusfab]

Mmmm can't remember? Is that oxygen reading normal for an Esprit?

[jonroberts]

All 4 gases need to be read together to be honest. The HC, CO and CO2 are the most relevant ones. Are you certain that reading was O2 and not CO2 ?

[Lotusfab]

Yep O2, seems high. Whats your o2 reading?

[jonroberts]

Can't tell you I'm afraid. The O2 sensor on my tester had expired, so it's gone away for replacement and calibration. Will tell you when I get it back ! 

[Lotusfab]

Thanks Jon.

[Lotusfab]

MOT test 1

Fail!! ????????

Well might as well try for Pauls record. Failed on three things, none of which were expected.

1. Exhaust leaking. Took it all to pieces and found a hole in the mid section, that explains the 10.4 O2 reading. Ordered a new section from S and J. Emissions passed.

2. Lower Universal joint on near side wishbone had dropped out of the wishbone!!! A scary drive to the test station. Have ordered a new one and will ensure its fitted properly. This is a friction fit within the wishbone. Surprising!

3. Headlight beam too high. Can't adjust as don't have the kit. Will let the garage do it. 

well could have been a lot worse! Hope to make Lotus day, even if it is on foot! Fortunately it stayed dry!