W124 230 TE poor idle (again)

[The Crooner]

OK reume:

Bought car very cheaply with intemittent idling problem.

Replaced idle control valve, no better.

Had it at a Bosch service centre on Friday who said that there was no signal coming from the ECU to the idle control valve.

Sourced another good ECU from a car with no idle problem.

No better.

Any pointers at what I should look at before spending more money?

If I take it to a main dealer would they be able to "plug it in" and give me a definitive answer?

Cheers

Tony

 

[dragon]

Buy a newer better car if you don't enjoy the fun.

 

[The Crooner]

My wife's "newer, better" "if only everything was as reliable as a XX", has cost more in one repair than I have spent on the 230, and I still have change.

I do enjoy the fun, I'm just getting a bit frustrated because I cant mend it with spanners and common sense.

Tony

 

[simon_wall69]

No signal from the ecu may not definitely mean it is the ECU, as there must be connections between the two.

 

[The Crooner]

Agreed, trying to trace the wiring.

I think a part of the engine to ECU loom may be defective.

Tony

 

[The Crooner]

To all who suffer from poor idle.

Make sure your idle control valve is fitted the right way round.

DONT ask me how I know...

 

[television]

Good one and I am pleased its sorted

 

[The Crooner]

Yeah, that and a very poor connection to the three pin temperature sensor, which we resoldered.

Going to have to replace some parts of the accelerator linkage as there's a lot of wera there.

Also noticed today a pump in the heater circuit, it comes on with the ignition.

What is its purpose?

Thanks

Tony

 

[television]

Yeah, that and a very poor connection to the three pin temperature sensor, which we resoldered.

Going to have to replace some parts of the accelerator linkage as there's a lot of wera there.

Also noticed today a pump in the heater circuit, it comes on with the ignition.

What is its purpose?

Thanks

Tony

To circulate the water when at idle, so that the heater keeps your tootsies warm

 

[SilverSaloon]

Buy a newer better car if you don't enjoy the fun.

what a pointless reply

 

[The Crooner]

To circulate the water when at idle, so that the heater keeps your tootsies warm

OK chilblains...here we go..

 

[The Crooner]

I thought I would post up a "where we are" update.

My neighbour and I have had several tuning sessions with the car. I had already changed the idle control valve - when it was refitted correctly it made some difference to the idle.

Since then, and with the generous help of many other posters we have probed all of the controllers and sensors.

We have also rebuilt the accelerator linkage and adjusted the control rod to fuel accumulator length, to ensure that that it was set correctly at rest. This made the biggest single difference to the running and idling of the car, and I urge all those with poor running/idling/intermittent faults to examine carefully the operation of their linkage.

Today we have tested the air temperature sensor and the engine temperature sensor, which both gave abour 4.5Kohms at cold. Television told me it should be 6 at cold, but I guess cold in Bavaria in winter is a little different to the cold I experienced outside today on the East Coast.

So now we have a good idle, the car has stalled once in the past 10 days, and its performance is quite sprightly compared to when I first got it.

It has had a new rotor arm, plugs and plugleads, and a very well cleaned dizzy cap.

We are now left with some quite discernable "hunting" at idle, the rev counter moves by at least 100 rpm in either direction.

We have probed the voltage on the lambda sensor, and there are voltages there, and they fluctuate with engine revs.

So I think there are two final things to do:

change the lambda - it looks very original

take off the inlet manifold and replace the gaskets.

Comments from the gurus please.

Thanks

Tony

 

[television]

Well the cure for hunting on the V12 engines is the inlet manifold gaskets, so why not on this,,even if it is a vacuum fault it will show different voltages as the revs go up and down, so care is needed in how you interpret any meter reading,,conformation can be had by revving the engine on the throttle..

 

[The Crooner]

conformation can be had by revving the engine on the throttle..

Could you please tell me what that means to a numpty like me?

 

[television]

You said the voltages were changing as the revs go up and down on idle, to double check this, alter the throttle by hand to see if you get the same voltage change, if the voltages do change then that item where the voltage changes could well not have a fault

 

[The Crooner]

I'm sorry, I confused you. The voltages on the Lambda sensor vary with throttle position, as well as at idle.

 

[television]

Then I think that the 02 sensor is working correctly, its purpose is to measure the richness of the fuel, as the enine hunts then the exhaust gas changes and the 02 sensor is trying to correct it, I wonder what would happen if you disconnected the 02 sensor from the engine ECU to prove the point

 

[Mercedes 190E]

I didnt think that age of car had an O2 sensor ?

 

[television]

I didnt think that age of car had an O2 sensor ?

Yes a CAT equipped car needs one it also has an EGR valve,,is this stuck partially open


http://www.detali.ru/cat/oem_mb2.as...+++717.413&CT=F&cat=15U&SID=49&SGR=030&SGN=01


http://www.detali.ru/cat/oem_mb2.as...+++717.413&CT=M&cat=504&SID=14&SGR=090&SGN=05

 

[kth286]

A simple vacuum gauge will show a manifold leak.