Club 80-90 Forums

1.9 DG all standard, original engine and carb etc.

Van runs well except...

When properly up to operating temp the idle speed goes up.

I'm not familiar with the Pierberg so can someone point me in the right direction? I don't want to upset any other settings since it is all so good otherwise (touches wood).

Should I be looking at what I would describe as a long screw to the right of the carb when seen from behind? I find Haynes somewhat vague...

Thanks in advance

Michael



 

Barking up the wrong tree I have been.

I have read Haynes yet again and search the forum. It would seem that the hot idle adjustment is on the other side of the carb, ie towards the front of the van. I think I have found it but it seems to have a loose plastic knob type thing on it. This is not mentioned in anything I have read and it is all very hard to reach.

I assume hot idle is adjusted with the engine hot?

No, that's the fast idle adjustment screw for the choke cam, which shouldn't need any adjustment if it's working well from cold.
Your first post was correct, the long screw that points towards you when viewed from rear of van, RHS of carb, is the main (hot) idle adjustment. If that does not bring the idle speed down it may be that the throttle cable has no free play (adjusted at the pedal end). This can happen when new cable is unwittingly fitted with engine cold and auto-choke on.

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Check the choke is operating correctly, it’s possible someone has increased the idle when cold to keep it running which has lead to an ever faster idle when warm, check the shut off valve is operating correctly too

Also check timing , mixtures and for anything loose leaking etc

Thanks both. Apart from my inability to decipher the Haynes manual I am obviously over thinking this.

I used to be familiar with older carbs and Bosch D jet systems etc but the Pierberg looks a bit daunting from a distance...and it has wires!

I'll give it a go and we'll see.

 

Long screw does nothing but I notice there is no slack or play at all in the accelerator cable. Has my camper stretched a few mm in the heat?!

Will investigate further.

The long screw really appears to do nothing, seems sloppy and turns without coming to a stop..

In the normal course of event which way would it turn to accelerate or decelerate?

Passed its MOT today with no advisories...though the exhaust looks as if it may fall apart in a year or two...

Normally screwing in clockwise would increase rpm.

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Do these screws we are talking about have other parts in line with them to keep them tensioned when turning ie a spring of sorts, thinking out loud again but must be more than just a matter of tightening and loosening otherwise vehicle vibration would loosen them.

Displaying my lack of knowledge about the Pierberg I haven't a clue...and have yet  to learn the detail of the thing.

Having said that, with a fast idle vibration is kept to a minimum!!!

The long screw just props open the throttle - you should see it rests on a little notch on a plate on the shaft. There is no voodoo or black magic like some screws on carbs, its mechanical. 

Sounds like your screw might have stripped - does it visibly change length as you screw it in/out? 

T25Convert wrote: ↑26 Jul 2021, 10:39
Sounds like your screw might have stripped - does it visibly change length as you screw it in/out? 

This never occurred to me, thanks, I will take a look, my suspicion is that turns without changing length which implies just what you suggest.
 

...and...after a week in the West Country, all good but the fast idle persists and the van pops and bangs when going down steep Devon hills under engine breaking. 

Sounds to me like a butterfly somewhere is not closing properly?