Tuning The 2.1 Td Engine With Bosch Pump

[B1ack_Mi16 67]

Not really a 205 question.

 

But last night I adjusted some on the main adjusting screw for the dieselpump on my 405 2.1 TD.

Idle went from 800rpm to 1500rpm and the engine is noticeable more powerful (and smoking much more ) than before.

 

Is it a separate idle adjustment screw I can use to get the idle back to a sensible level again?

 

I know it's possible to adjust the cold starting function (the one with the wire from termostat housign attached), but I was under the impression that this will alter the injection timing to increase/decrease revs and not the fuel amount. Can anyone fill me in on this matter?

 

Not easy to be a noob at these diesel engines

[opticaltrigger 52]

Hi Ive toyed with thiss myself in the past and as far as I can tell theres not much way round the problem.

If you increase the volume of fuel delivered the idle speed will increase as a by-product.

 

One thing though and Ive not tried it myself but you could try and throttle the air intake just enough at idle to bring down the revs but you would need to unthrottle it as soon as you leave idle.

I belive that VW use a throttle body on some of there diesels which may be worth a look at.

 

O.T.

[welshpug 1,661]

there is a separate idle adjustment yes, is it a Bosch or a Lucas fuel pump?

[B1ack_Mi16 67]

there is a separate idle adjustment yes, is it a Bosch or a Lucas fuel pump?

 

It is a Bosch pump as the topic says

 

Last night I did some adjustments to the stop screws on the cold start function so I got the idle back to 1000, also the throttle wire stop position was slacked off a bit (it was a little over-tight to begin with) so the idle is back down to 900-1000rpm now.

 

Anyway I suspect that my fiddling with the cold start stop screws have retarded the injection timing as it makes lot less sound now.

 

Is there another separate idle adjustment apart from this cold start function I have been fiddling with?

[welshpug 1,661]

the 2 screws either side of the cold start lever? that's it, one will give cold idle speed and the other will give hot idle speed.

 

the only other adjustment to the idle speed is the max fuel screw as you have found.

[B1ack_Mi16 67]

Ok thanks..

 

What I really is wondering...

 

These stop screws, are they adjusting the amount of fuel, or are they altering the diesel injection timing to change the idle?

 

If the latter the engine will have wrong timing at all revs I suspect.

[welshpug 1,661]

I'm not 100%, but I think they alter the advance/retard timing of the pump, the max fuel screw alters how long the injection pulse is.

 

 

I have always wondered how you would set up a mechanical diesel pump before fitting it to the engine, as you have to start somewhere even before you set the pump timing to the engine.

 

When fitting a new Bosch pump you use a DTI gauge and rotate the pump body to achieve the correct timing.

[B1ack_Mi16 67]

Yes I'm aware of that timing adjustment.

 

However if it really is the advance/retard that is adjusted by the idle screws then the engine will not have a correct timing as long as you start altering the max fuel screw and taking the idle back down by retarding the timing.

 

I will just have to measure consumption and see if I can live with it or not

[weejimmy 1]

at the back of the pump there is a screw that stops the lever returning. this should be unscrewd ( i remove it)

it will bring back down the idle,

also make sure your throtle cable has some slack so its not restricting it.

 

the hot / cold idle adjusters do not adjust timing they only adjust the minimum revs.

 

when tuning the bosch pump i somtimes have cars at near 2k rpm idle and can alway get them back down to 850rpm.

[ravydavy 0]

I had a bmw 325tds that i wanted chipping up to get more power. I called dastek and he said one problem with messing with diesels is the exhaust gas temperature. He said the more fuel you add the more power you get. But the downside is the heat. When they remap diesels they drill the exhaust manifold and put a temp probe in to get the reading. So be careful. Don't want you wrecking the turbo.

 

Regards David..