Mixture too rich at Idle/Low rev

[putin]

After I did my head work last year I was having some trouble getting it running smoothly.
In the end I resorted to adjusting the mixture myself and was happy with the result.

However I had a nagging doubt that I shouldn't be messing with such things so I took it to a Dyno Tuner to get it checked out last weekend.

He quickly informed me that it was running waaaaay too lean. The plugs had begun to melt/bend and I've lost come compression on 3 cylinders (although it was never perfect).

So after 6 hours work and many dollars I've got it back.
The Tuner is happy with the mix at the top end, 12.2-12.7:1 A/F ratio, but at Idle and low revs it's far too rich and the he can't get it down.

It looks like I had the mix right for low revs but at the top end it was doing damage, now the situation is reversed.
Top end is nice and safe.. bottom end is undrivable!

It's sluggish when cold and as it warms up it starts stalling at lights. Revs drops below 500rpm and dies.

This is pretty much as it was after the head rebuild.
Increasing the idle has stopped it stalling but it still splutters and misfires while cruising. I need to track down the real problem.

Has anyone experienced this?

Haven't had a chance to experiment with it yet and could do with some pointers.

I'm wondering if the Cold Start injector is staying on, might explain the problem getting worse when it is warm.
After that I guess I'll have to buy a fuel pressure test kit and check the WUR operation.

Anything else should I be checking?

[Jim]

The helping air valve which gives the cold engine more air but closes when getting the engine warmer. At age this valve starts to move less and it might get stuck into 1 position, making it impossible to adjust the engine for both cold and warm state.
Just an idea.

[Mcinek]

After that I guess I'll have to buy a fuel pressure test kit and check the WUR operation.

This might help you when adjusting WUR.

[putin]

Thanks guys. I'll be tackling it this weekend.

That WUR adjustment video is interesting. I've never heard of the concealed pressure adjusting hex socket before.

[EDIT]
Ah.. I guess that would be because ours don't have them

Just found this great article about making the WUR adjustable:

http://www.pelicanparts.com/techarticle ... up_reg.htm

The comments section links to pictures of one that has been modified.

[Mcinek]

I set the control pressure like on this video on my 323i and now the car runs much better. The 323i WUR has got this allen key screw and the presure can be adjusted, But I didnt drill the WUR plug like on the video, instead of drilling this I disassembled WUR, removed the plug, set the presssure with the allen key and then put the plug back.

In my case the control pressure was too high.

[putin]

Hmm.. maybe I have a different model to you. Mine is the 0 438 140 005




Don't know how I would open that bottom section. These are old photos so I can't examine it right now. I don't remember there being anything behind that central hole in the top photo.
Perhaps I have to just tap the plug in and out to adjust.

[putin]

Cold start injector and thermo-time switch are both dead.

Hooked up injector pins to 12v and ground, jumpered fuel pump - no flow. Tried swapping the injector connections over incase that makes a difference, no joy.
Fuel is flowing, I can hear the pump running and the fuel line to the injector twitches as the pressure comes on.
The injector got very very hot while I was testing.

Checked the Thermo-time switch on the thermostat by connecting pin 'W' to 12v with a test lamp, doesn't light it when engine is dead cold. Ambient is 21C today.
The other pin, 'G', lights the test lamp, cold and hot.

So.. two things to replace but neither explain my rich mixture at idle.
I think the car runs OK when cold because the over-rich mixture is doing the job of the non-functioning cold start injector.

Things that do work. Power to the WUR is good and the WUR element is showing a resistance of 26 ohms which is correct.

I'll try to buy a fuel pressure tester next week. Expensive things though.
Found one in the US for $60 but postage is daylight robbery.
Anyone know where I can get one at a reasonable price in Aus?

[putin]

I got a pressure tester a couple of weeks ago from the US (http://garage.ideola.com/prod-Tools.html) delivered via a forwarding company (http://www.shipito.com) so it ended up costing around 120AUD.

Finally had a chance to use it over Easter.

My figures don't seem terrible but will need some adjusting.

Cold Control Pressure: 0.6 bar (ambient approx 18 C)
Warm Control Pressure - Engine Stopped: 3.1 bar
Warm Control Pressure - Engine Idling: 3.9 bar
System Pressure: 4.6 bar
Leak Test / Shutoff Pressure after 20 mins: 1.9bar

Cold Control pressure is definitely low, Warm is at the top end of its spec range and System Pressure is at the bottom end.