Running well or running weak ?

Graeme Clark · Post by **Graeme Clark** » Sun May 28, 2006 19:01

Had the car in for the MOT which she failed due to the horn and a knackered top link bush. The emmission test came through as being 0.027 which the tester was amased at so much so he did it a second time as this was massivley under the allowed amount. - does this mean the engine is fine or running a weak mixture which could do harm ? Was going to take the car to Nobles in Chesterfield for a rolling road set up and tume the mot tester said in his opinion I probably would be wasting my money. 89SE with 90K miles using optimax fuel
Cheers, Graeme

Markexel · Post by **Markexel** » Sun May 28, 2006 21:11

The emissions test to me seems a bit of a joke ,its done at tickover.I have never had a problam with passing that on my Exel or any other car,best of it is though my me Exel really smokes bad when u put ur foot down.A combination of burning oil and those carbs waisting fuel!!

Skeggy · Post by **Skeggy** » Sun May 28, 2006 22:43

Depends which emissions your talking about.
There are Co2's and Hco's ( I think!) - just started typing and can't remember

Again I can't find the info I want to post - but it's something like cars over a certain age are allowed 'worse emissions' .
Have a look at:
http://motforum.proboards44.com/
They may be able to help.
Anyway the only way I can think that your car can be running lean (weak) would be blocked jets and that would mean very bad running.
But lean running is very bad news for engines so check it out before you do any damage.
One final thought - have a look at the exhaust pipes if they are black inside then that shows that you are running ok (maybe rich) but if they are grey or worse light grey, then you are running lean.
Hope this helps.
Steve

Skeggy · Post by **Skeggy** » Mon May 29, 2006 18:55

Graeme,

From the link posted in another thread the co2 should be 0.5 - 1.5.

So 0.027 is low - but I'm not sure what that means

As you say the exhaust pipes are black and the car runs well I wouldn't worry.

Can't get 4* round here but I'm going to treat the car (and me

) to some bottles of octane booster asap.

A rolling road set up is well worth the money so long as the person doing the setting up know what they are doing.

Regards,
Steve

Peter · Post by **Peter** » Tue May 30, 2006 18:36

mine was richened up at the last service and mot to about 6% i believe, i'm not sure if thats mot passable or not probably borderline but miles (fibreglass services) told me the engineers at lotus said it ran best (most power, best delivery) at 6% to 8% they left the factory with much lower settings though

Skeggy · Post by **Skeggy** » Tue May 30, 2006 18:53

Peter wrote:mine was richened up at the last service and mot to about 6% i believe, i'm not sure if thats mot passable or not probably borderline but miles (fibreglass services) told me the engineers at lotus said it ran best (most power, best delivery) at 6% to 8% they left the factory with much lower settings though

Very good tip - I'll have to check mine.

Not 100% sure but I seem to recall that cars built before 19?? have no ristriction on co2's. Will try to check this out.

Regards,
Steve

Steve C · Post by **Steve C** » Tue May 30, 2006 19:02

My 1990 SE had to hit 3.5% for the MOT ... first checkwas about 6%, a quick tweak on all the mixture screws and it sailed through at about 2.5% ... oh, the other fix needed was to crimp up a headlamp bulb connection.

Normally it sails through without such major repairs

Redexcel · Post by **Redexcel** » Tue May 30, 2006 19:09

Lifted from any recent Haynes manual....

Regs for emissions are:-

August 86 to July 92, max CO is 3.5%, Hydrocarbons 1200 ppm
Prior to Aug 86, max CO is 4.5%.

Aug 92 on, and the max CO drops to 0.5%, & 1200 ppm HCs, which is why cars registered after that date have catalysts.

All the above at idle. I believe other tests are carried out at between 2500 and 3500 RPM for post 92 cars ( eg lambda sensor)

Redexcel · Post by **Redexcel** » Tue May 30, 2006 19:12

Steve C wrote:My 1990 SE had to hit 3.5% for the MOT ... first checkwas about 6%, a quick tweak on all the mixture screws and it sailed through at about 2.5% ... oh, the other fix needed was to crimp up a headlamp bulb connection.

Normally it sails through without such major repairs

Steve,

How is it running on the leaner setting? Or did you return it to pre MOT state once you got home

Steve C · Post by **Steve C** » Tue May 30, 2006 19:28

It's running ok ... it has always been a little hesitant when opening the throttle and no amount of carb balancing seemed to solve it (although it could be reduced). Opening the throttle more seems to help, perhaps due to the squirt of fuel from the accelerator pumps?

If i can't tune this out with the FI installed, I'll be gutted!

Redexcel · Post by **Redexcel** » Tue May 30, 2006 19:37

Steve C wrote:It's running ok ... it has always been a little hesitant when opening the throttle and no amount of carb balancing seemed to solve it (although it could be reduced). Opening the throttle more seems to help, perhaps due to the squirt of fuel from the accelerator pumps?

If i can't tune this out with the FI installed, I'll be gutted!

Yeah, FI should sort it I would think.
That slight hesitation you mention is what I was enquiring about on my carb mods thread.
Maybe I'm not going mad after all.

Peter · Post by **Peter** » Tue May 30, 2006 22:38

its a subtle differance but i noticed mine is a little keaner in the midrange and smoother at low rpms, your unlikely to notice a huge transformation unless the car was very badly setup, or there is somthing not actually working properly