Car not firing on all cylinders

[richardhallett99]

+2 S130 (72)
I have been scouring this site for specific information that relates to my current issue. I have found several similar leads but nothing exactly to match my problem:

About three months ago I started the car and it was clearly not firing on all cylinders. I took out the plugs - cleaned them off and the car ran fine. I switched the car off, restarted it and the same happened again. This time on investigation the plugs were wet.

So

I replaced the plugs - took it for a drive and things again were fine. The next day - again - it is chugging away on less than all cylinders. And so the story goes on - each time I start the car on a different day it is neccesary to clean the plugs first or it will not be firing properly. I will typically get 20miles before I need to take remedial action.

The car is garaged, serviced every six months and not driven too hard.

I know that I am not special and hope that it is a standard problem that someone with more mechanical knowhow than me can help with?

Any and all greatly appreciated

[alaric]

Hi Richard. It does sound a lot like common ignition problems that seem to crop up regularly on the forum. Not knowing what your ignition is, I'd suggest, damp in the distributor cap, the points in poor condition, cracked distributor cap or rotor arm, poor connections to the ignition coil / circuit & earthing, the coil itself shorting out. Is the engine earth strap ok?

I have the Aldon ignitor in place of points which I think is about ?30. One remaining concern I have with my own car, which is the same model as yours, is that there's no seal around the distributor cap.

I look forward to hearing what the solution actually is... sad eh!

Sean.

[rgh0]

Richard

Unfortunately your symptoms could be caused by a range of problems and you really need to work systematically to fix it.

The order I would check things are

Starting technique

My method is as follows not gospel but it works on my cars.
2 or 3 pumps on the accelerator and turn the key with foot off the pedal. If does not start a couple of more pumps and then turn key while slowly depressing accelerator. If it still does not start repeat the second step once more. If it does not start then you have a problem and more starting attempts will probably not help

Next the ignition and electrics:

1. I am assuming the battery is fully charged and the engine cranks well.
2. Are you using NGK BP6ES or Champion N9Y these are the best plugs for your use. (I prefer NGK's). The Lotus recommended plugs are to cold especially for your usage.
2. Is the ignition system standard and are all the components is good condition and the timing set right. Does it produce a good spark when cranked with the plugs removed. If an after market ignition has been fitted has it been installed correctly.
3. If the engine runs OK for 20 miles and then gives trouble I would look at replacing the coil and / or condensor as both can become faulty when they warm up.

Next the fuel system:

1. Are the jets standard or have they been changed. If not standard and you dont know why return them to standard.
2. Are the float levels set right and the float valves working freely and cutting off the fuel properly when shut.
3. Is the fuel pump delivering OK into the carbs with no blockages. If a non standard pump is the fuel pressure set right (around 2 psi)

Finally general engine condition

1. Compression do you have even and adequate compression in all cylinders
2. What is the engines oil consumption and are the plugs oil fouling
3. Are the cam clearances and timing set right

Somewhere is all of the above you will find your problem in 95% of cases.

Good luck
Rohan

[Hamish Coutts]

Good one Rohan,

This may seem a daft question butt how do you check the fuel level in a Dellorto? What should the fuel level be?

Hamish.

[rgh0]

Hamish Section L page 67 of my plus 2 manual part no X050 T 0327Z provides the details for Delortos.

i.e

1. Hold the float chamber in a vertical position. The tab should be in light contact with the needle.

2. The distance between the top of the float and the cover including gasket should be

DHLA 40 14.5 to 15.0 mm
DHLA 40E 16.6 to 17.0 mm

A further note says

Where type DHLA carbs are persistently flooding reset the float chamber to 16.5 to 17.0 mm and fit a Viton tipped needle valve ( B036 E 6060Z).

I persume this is the type of valve fitted in the DHLA40E

Rohan

[Craig Elliott]

Are you using a lead replacement additive? - I had similar problems with my S130/5 with Dellorto carbs when using Valvemaster + (i.e. the one with an octane booster) with unleaded petrol. The sparkplugs would soot up very quickly causing a misfire. Using Valvemaster without the boost
solved the problem.

C

[lotuselan2]

Worn valve guides tend to pass a little oil while motor is sitting in the garage. On a TC the first cylinder tends to have more of a pool of oil when static. Engine runs fine once started, but has one or more plugs oil fouled (not much but oily not sooty) when starting. On my Europa TC I was usually able to unfoul the plugs by pulling off the offending plug wire and putting a bit of air gap between the wire connector and the plug top. This boosts the spark voltage and can clear a slightly fouled plug if you are skilled and / or lucky.

[richardhallett99]

Gentlemen

Many thanks for all of your help. RGH - next weekend I will work through your list of suggestions and lert you all know how things pan out. I have a funny feeling that quite simply my car prefers high Octane Super unleaded with additive rather than LRP. Goodnedd knows but I have had three trouble free days.... Oh great - I had to go and say it...

[rgh0]

Lead replacement petrol and some of the lead replacement additives bottles used to replace lead have a tendency to put deposits on spark plugs. When combined with a marginal ignition system it could produce your problems ( or at least make them worse). I would just run the car on straight premium unleaded. You dont really need any additives

Rohan

[pamitchell]

Correct me if I'm wrong but I thought twincams did not need lead additives as the valve seats were hardened steel since the head is aluminum.
Phil
San Jose CA.
69 S4 FHC

[richardhallett99]

Can anyone else expand on the additive/no additive arguement?

[1964 S1]

Hello from the 'States.... the unleaded thread has been dealt with several times before on Elan.net. I've been driving for years and years with unleaded and no additives and have yet to notice a single problem. Maybe the additives ARE fouling your plugs.

[1964 S1]

Hello Richard, I just re-read your first post and noticed "not driven too hard." I've found with Lotus, that could lead to your plug fouling/wetting problem. I believe these twin cams need to be revved and allowed to scream a bit to stay healthy. When you "get on it" do you see any black smoke out your exhaust? And finally, are your chokes fully opening?

[chrishewett]

I have always had a bit of a problem starting my +2, I usually use the choke and have never been impressed with the length of time it took to start. I have now started to use the method Rohan recommended earlier in this thread. To my delight it now starts first time!
Thanks Rohan.
Chris

[richardhallett99]

64 S1

When I say I don't drive it too hard - I mean that I don't thrash my 35 YO pride and joy to within an inch of her life - I still drive it in the spirit that it was intended and she sounds great for it. I do not feel that my lethargic driving style is such that this is causing the plugs to foul!

My choke - like many others of its kind - was disconnected well before it came into my hands.

Hopefully this weekend I will get the chance to both take her out for a significant drive, fill her up with a tank full (or half a tank to cut down on fumes!) of Super and try out some of the tests alluded to above. Will keep you all posted