190e 2ltr erratic idle

[TheJim]

Hello chaps,

Now that the car is back on the road after six months of grief with the head gasket I am starting to sort out all the little niggles.

The only thing that is still a bit of a mystery is the idle speed-

When you start the car from cold the idle speed is about right, 1000/1100 rpm or so. When you have moved the throttle the revs stick at 2000 rpm whenever you are stationary and idling. When the engine has warmed up it then idles at about 1500 rpm.

All I have done so far is whack some wd40 on the throttle linkage. Which has achieved sweet FA.

Before I start ripping everything apart I just thought I would run it past you guys.

My train of thought has been:

The paddle in the air intake sticking?
Idle air valve?
Throttle cable/linkage sticking?

The symptoms feel mechanical to me- but has anyone here had this same problem?

 

[television]

It could be that you have upset the linkage somewhere. It cant be the
Idle ECU/main ECU switching as your idle speed is way out. What injection system do you have.

Malcolm

 

[TheJim]

The Bosch Jetronic I think. I think it must be a cable or return spring or something..... I refitted the throttle return spring though- I remember painfull and fiddly experiences like that!

 

[DAD190E1990]

Had this problem once, although i have no manuals to hand for reference now - it's an idle air valve, bmw's do the exact same thing. Try a secondhand one to eliminate it but i'm fairly sure it's that which will solve it for you. I seem to remember they are not drasticly expensive, go to Euro car parts or German Swedish French. I would not say it's electronic but then i could be wrong having not actually seen the car. Hope you get it sorted out.

 

[TheJim]

It is one of the possiblities i have considered. I was trying to think of other, simpler things to check first......

Cheers.

 

[Ian Brown]

whats about all the vacum pipes jim are they all on and in the correct places
just a thought. has this problem just developed after having the head off?

 

[malcolm E53 AMG]

On the Bosch K system there is an auxilary air device. Its sole purpose is to allow extra air into the intake manifold during cold starts. It is an electro-mechanical device with a heat sensitve valve that closes after a set time.

If this valve does not close the result is a high tick-over of approx 1500rpm due to a lean idle mixture.

I would imagine that the Bosch J system uses a similar device.

Hope this helps!

 

[TheJim]

Sorry I have not been about, I have had the Lurgey and been in bed....

Ian, yes this problem has only occurred since the head was off- but I don't think it is a vacuum pipe as a- I labelled them as I am rather anal and b- in the past couple of days the idle has been normal after a good run or the engine has been restarted when still slightly warm.

So I think it is one of these valve thingys- idle air mass/cold start etc.

I shall try to find the blighter and then clean it and failing that replace it.

Cheers chaps.

 

[Stevie A]

Jim -saw this posted by Pentoman on another 190 thread:

For idle problems look at:

Coolant temperature sensor (4 pin at front of engine)
Fuel shutoff switch (on throttle linkage)
Throttle position sensor (Built into bottom of throttle body, 3 wires)
Idle Control Valve (Right side of engine as you look in, 2 pin plug, a clean sometimes helps but sometimes you've just gotta replace it)

Russell
__________________
190E 2.0 & 2.5-16v

Hope it helps.

 

[TheJim]

awesome. Is the arm on the throttle linkage meant to be in contact with the fuel cutoff switch when the throttle is closed? Because mine is not touching......

 

[Stevie A]

awesome. Is the arm on the throttle linkage meant to be in contact with the fuel cutoff switch when the throttle is closed? Because mine is not touching......

Don't know but somebody else should. Experts help please.

 

[cossiedude]

yes the throttle linkage should be in contact with the microswitch when throttle is closed, if not then it can cause high idle speeds.

Also high idle speeds are sometimes caused by air leaks in all the pipework and should be the next thing you check, listen for air leaks whilst engine running

G.

 

[TheJim]

Well the arm is definitely not in contact. I shall have a play with that before I get a new Idle control valve.

Cheers guys!

 

[mike65]

It should touch when throttle is closed. Its easy to tweak the end you'll see a threaded nut thingy when you remove the airbox which can be turned one way or the other.



Mike.

 

[TheJim]

I suppose I should see what happens if I press the switch with my finger and if that does the trick I shall adjust the cable and linkage.

I can only imagine that the adjuster drifted when the linkage was ondone when I had the head off.......

Thanks for all the advice guys.

 

[TheJim]

Well, I have cracked it!

The linkage was not touching the switch. So I adjusted it. The car idled fine until I used the throttle and then it was not returning fully. I took the whole lot apart and found out that it was the metal spiral that reinforces the outer of the cable dragging on the cable inner. So a bit of judicious filing later and it works a charm!

Trouble is, the linkage end is working fine now- but the pedal has loads of travel before the throttle starts opening. I can't see how to adjust this out. Bugger. Still, the car drives fine now and for that I am thankfull!

Cheers guys.

 

[tom7035]

Trouble is, the linkage end is working fine now- but the pedal has loads of travel before the throttle starts opening. I can't see how to adjust this out. Bugger. Still, the car drives fine now and for that I am thankfull!

Cheers guys.

I think there's some sort of cable adjustment under the accelerator pedal on the 190. Something to do with full throttle stop? You'd need to consult a manual to adjust cable accurately as it involves what's happening under the bonnet at the throttle body end too.

 

[TheJim]

Aha, I shall have a rummage when the weather has warmed a bit. I have had it with middle of winter car repairs without a garage!

Sounds like a fiddly job. But it can wait for now. I am not exactly ragging the car seeing as I have just rebuilt the top of the engine! So full throttle is not required just yet.......

Cheers.