Cold start mechanism explanation 406 1.9td

[JonnyH]

Hi there. I've got a problem with my cold start mechanism and idle on my 406 1.9td can anyone clearly explain how this system works as I'm not entirely sure I'm understanding it correctly.

Thanks

[GingerMagic]

If its anything like my old 306 1.9dt then it would never start without using the glow-plugs - even with a warm engine. Once the glow-plugs get worn the car took ages to fire up and belched smoke everywhere with a lumpy idle for about 2 minutes..!!

May I ask what your 406 problem is?

[gumby6371]

The cable usually sticks giving a constant cold start setting.
Try slackening the locking nut and giving the cable a few good tugs with your fingers.
Also check the vac pipe for splits

Mine dropped from 1000 to about 850 after I did that

[Rolebama]

From what I remember of my 306 TD, it only had a fast idle worked from a waxstat arrangement, and the glow-plugs. When cold, when the glow plugs activated, it was just a matter of turning the key, and it would start after a second or two. When warm, I had to give a touch of throttle for a little extra fuelling.

[Uberderv]

There are two mechanisms on the Bosch pump to aid cold starting. The lever nearest the glow plugs is usually controlled by a wax stat, this increases idle speed when cold and reverts to hot idle settings once warm. You can adjust this via the two screws or the cable tensioner.

The other is on the front of the pump and advances the timing by moving the roller cage in the pump. By applying 12v to the solenoid it increases advance by 5-8 degrees. I have mine (2.1td) wired to the glow plug circuit as it has a post glow of 180sec, this is ideal as you don't want it activated all the time.

[JonnyH]

Thanks everyone. The problems I was having was difficult cold starting. I traced that down to a faulty glow plug so I replaced the lot. Nasty job, no room.
What I'm trying to get working is the mechanism that increases the idle for a time to get it started when cold. And I'm trying to get a gist on how that works as mine is clearly doing nothing.
When you say there is a wax stat, where is that? My arrangement on my Bosch pump seems to have a lever with two screws either side and a cable going to a diaphragm connected to the servo. Again this does nothing and I f I pull it I believe it drops the revs down rather than up. It may be stuck as you say.
The lever with the two screws seems quite stiff but I can adjust it though I'm not clear that I'm adjusting it in the correct manner. Any clues in how to set this all up properly?

Thanks everyone

[Rolebama]

There is probably all the info you need on the website http://www.pug306.net/
You will have to register to read their Knowledge Base articles, but there is a heck of a lot of info there about Bosch pumps.

[Doggy]

Guys, the only 1.9TD 406's I've seen, (97R / 98S), have had ecu controlled Bosch pumps, which are somewhat different to what you'll find on a 306/405 etc. I believe all 406's have similar equipment. You can monitor a surprising amount of parameters via PP2000 on these.

May well be the same basic mechanics, but the way the bits are controlled is different.