S123 230TE - idle issue

[ShivaYash]

Hello all,

Been a long time since I last posted here.

My S123 is causing a few issues. It fires up from cold, without issue, but the cold idle is quite low. Around 700 RPM and the battery light is ever so slightly ON.

I've tried the large flat-bladed screw under the air filter housing, but this increases idle generally. Warm idle is now a little on the high side.
I don't think the Warm Up Regulator is at fault, as she starts on the button.

Plugs and HT leads are new.
Cap looks OK, as does the coil.
I ran a fuel cleaner recently.
I only use E5 fuel.
Air filter is clean.

I suspect a small vacuum leak, under the air filter housing, I need to remove that and have a look and perhaps replace some rubber pipes.

But in the meantime, what can I do to balance the cold idle, to around 1000 RPM and then get the warm idle to 750-800 RPM?

Greetings from Berlin,
With thanks,

 

[mattkh]

Where is the car..?

 

[ShivaYash]

Where is the car..?

Berlin. Why?

 

[mattkh]

Berlin. Why?

Atmospheric conditions e.g. temperature, humidity, hilly area or flat area so the car engine tilted which may affect fuel flow, type of fuel additives used.

 

[star]

Check the co2 mixture as it alters with the air idle screw.

 

[ShivaYash]

Check the co2 mixture as it alters with the air idle screw.

I'll do that next time the car is at the workshop - I don't have the tool to measure CO2.

 

[malcolm E53 AMG]

Not sure of the fuelling system on this car is it Bosch K-jetronic? If it is the Auxiliary Air Device which controls the cold idle speed may be faulty and shut closed when the engine is cold.

 

[ShivaYash]

Not sure of the fuelling system on this car is it Bosch K-jetronic? If it is the Auxiliary Air Device which controls the cold idle speed may be faulty and shut closed when the engine is cold.

I think it is K-jetronic.
Within 2 mins of running the cold idle is good, since I've adjusted the idle screw.
I think the linkages need to be cleaned and lubricated with some ATF... they don't seem that smooth.
I'll check things out this weekend, hoping for a little sunshine here in Berlin.

 

[malcolm E53 AMG]

That’s typical of this valve being closed when the engine is cold. I had one fail on my Ford Capri 2.8 injection but it failed in the open position which mean’t the tick-over was too high when the engine was warm. Like a lot of components used in the Bosch K system it relies on electro-thermo-mechanical devices which do fail.

 

[ShivaYash]

That’s typical of this valve being closed when the engine is cold. I had one fail on my Ford Capri 2.8 injection but it failed in the open position which mean’t the tick-over was too high when the engine was warm. Like a lot of components used in the Bosch K system it relies on electro-thermo-mechanical devices which do fail.

Thanks for the information. In your experience, it is easy to fit, I'm a home mechanic who specialises in making easy jobs look difficult, but get there in the end ;-)

 

[malcolm E53 AMG]

This is the valve and very easy to fit:

Mercedes-Benz W123 S123 Auxiliary Air Device Fuel Injector 0280140127 A00014109 | eBay

Find many great new & used options and get the best deals for Mercedes-Benz W123 S123 Auxiliary Air Device Fuel Injector 0280140127 A00014109 at the best online prices at eBay! Free delivery for many products.

www.ebay.co.uk

 

[ShivaYash]

A0001410925

 

[malcolm E53 AMG]

Yes, item 86

If you have adjusted the tick-over to compensate for the valve not operating properly there may be some adjustment back when a new one is fitted

 

[ShivaYash]

Yes, item 86

If you have adjusted the tick-over to compensate for the valve not operating properly there may be some adjustment back when a new one is fitted

Do you think A0001411825 would fit my M102 engine? It is available from MB and it is half the price of a second hand A0001410925.
Thanks.

 

[malcolm E53 AMG]

Sorry, no idea. What do MB say It may well be just a new part number and do the job?

 

[malcolm E53 AMG]

Hope this solves your problem let us know how you get on

 

[ShivaYash]

Hope this solves your problem let us know how you get on

Hi, actually the cooler weather and a slight turn of the idle screw has improved things.
The thermoswitch seems to be working. Cool starts have improved and are smooth. Idle at warm is around 800/850 RPM.
I'll continue to monitor.

 

[ShivaYash]

Hallo. I’ve installed a new replacement auxiliary air valve just yesterday. And adjusted idle to 800/850 (warm) with the gearbox in P.

Unsure if there is much of a difference tbh. The car always started on the button but I felt the idle at cold was a little low. This has improved a little.

Is there an auto choke function? What should the idle be at cold?

The car is still in Berlin, so the ambient temperature is around 8-9 degrees Celsius.

 

[mattkh]

What a lovely car.
If possible, please get a picture of what is under the bonnet.

 

[ShivaYash]

What a lovely car.
If possible, please get a picture of what is under the bonnet.

Thank you - it is a 230TE - M102 - shall snap a pic once it stops raining and I've had a chance to clean the engine bay...