Emission failure

[rob walker]

Gentlemen.
As some of you will know I am going through the tedious process of getting the car back onto Spanish plates as that is where it is going to spend most of its life.
I am in the final stages, which is the technical test.
The car was set up by the marque experts in the UK with a new 123 distributor and prior to that had a reconned injection pump.
She runs beautifully!

However it has just failed the Spanish technical inspection test on CO emissions.
She is reading 4.91% That had to be on idle as they never reved the engine.
The car was also resonably warm.

Unfortunately down here there are no real experts and I am really concerned about non experts playing with the settings, which have taken me a long while to get to, to have her running so well.

I have gone through all the search modes and have gleaned some info but not being technical on the injection side have a few questions.

Given the injection pump is reconned not too many miles ago and I am running the 123 distributor.

Is getting the idle CO down something that can be adjusted by the screws on the pump or does it need stripping down and adjusting inside?

Thanks Rob 

[mdsalemi]

Rob,

Sent you a PM.

[AGT]

Rob

I am going through the same process in France with my Citroen 2CV and preparing my 230SL.

Initially I had hoped not to require an emissions test because of the ages of the cars but not so.

Anyway, this may be a petro chemical urban myth, but the 2CV specialist who prepared and presented my 2CV for the Controle Technique told me to fill the tank with the highest octane premium brand petrol which I could find - not something my 2CV is accustomed to sipping. It passed.

Might be worth a try before you let anyone tinker with the set up of a sweet running car.

Best regards
Andrew
1966 230SL

[rob walker]

Hi Andrew,

Thanks for the good idea, but I already run her on BP 98 Octane, which the best you can get here (and most expensive!!).

[stickandrudderman]

What's the max limit allowable to pass the test?

[rob walker]

3.9%
It is exactly the same as a brand new car!!

[Benz Dr.]

My understanding of this system is that they tend to run rich at idle and also full load but lean out quite a bit at driving speeds. The air control valve has a lot to do with this as it opens faster through the mid range than does the injection pump. In other words, the air fuel ratio provides for less fuel at mid range speeds.

Some of these engines will barely run below 3% and most of them like 4% or higher at idle. You should be able to turn the IP back a couple of clicks which might be enough.

[stickandrudderman]

As Benz Dr says, you might be able to get away with weakening off the mixture sufficiently to get it through the test which is why I asked what the limit was.

[rob walker]

Sorry just to clarify, the limit is 3.5 mine was at 4.9 at idle.

I have found the old mechanic who used to look after the car years ago for the previous owner before I took it to the UK.

He seems to know what to do basically saying what other on here and the Tech Manual said, without me prompting.

It goes in on Tuesday, so will advise of the results and the subsequent running behaviour.

Thanks to all for their input.

[Benz Dr.]

OK, that's on the rich side at idle. You should be able to get it lower than that. I always change my oil just before I take my regular car in for an E test. Sometimes a clean air filter or new set of pulds is all you need.
I'm sure you will need to turn the knob on the back of the pump about 3 or 4 clicks to lean out the idle. I set mine as lean as it will go without affecting idle quality. If you get the screw inside of the pump out too far the knob will turn with the engine. If this hapens you will have to turn it back in a couple of clicks. If your mixture is still too rich you have some other problems inside the pump or a leaking cold start valve.

[rob walker]

Thanks again to Benz Dr and stickandrudderman.

By taking the IP down by a couple of clicks and adjusting the air control valve and a little on the timing the mechanic managed to get her down to 2.8 on idle.

However by the time I got to the test centre, about 60 kms, going through the test she was back up to 4.3??

Fortunately the tester took pity on this poor Brit, trying to get a Spanish registered classic through a modern test and he passed her.

Any ideas why it would have moved up again from 2.8 to 4.3 before I go back to the mechanic?

[Benz Dr.]

If your mechanic was able to get it lowered once, he should be able to do it again. Maybe one tester is clibrated better than the other. Which one is right would be my next question.

 You got a pass and that's a good thing.