[Grandad]

Hi
Having read the thread on 6 rib tensioners in awe I feel a bit daft broaching a relatively simple matter such as this, but....as ever.....we'd appreciate some help in overcoming our ignorance.
Today we've been trying to set the dual throttles such that we've got some throttle response and some tickover.
Initially we were adjusting the stop on the pre charger throttle so that the butterfly would not fully close. With the engine ticking over we noticed that at about 850 rpm opening this throttle any further did not increase engine speed.
This caused us to think that at this stage the speed of the engine was being determined by the idle control valve on the post charger throttle.
We therefore adjusted the stop on the pre charger throttle such that engine revs just dipped below 850......presuming that at this stage the butterfly on the precharger was passing very nearly as much air as the idle control valve on the post charger throttle......and then adjusted the stop on the pre charger throttle so that the butterfly would be opened a little bit more.
So hopefully we've got the butterfly on the precharger throttle capable of passing a bit more air than is passed by the idle control valve on the post charger throttle at tickover.
Does this sound right...or are we making a complete hash of it?
After this we endeavoured to adjust the cables to be as taught as possible without moving the butterfly on either throttle.
Whilst this sounds like half an hour's work we were pratting around with it for hours. The session included an early and short drive in the car when we got a very loud bang and a reluctance to run. Being certain that we'd popped either the charger or the engine we were somewhat relieved to find we'd blown an intercooling pipe off. This didn't stop us from blowing another hose off later in the afternoon!
Many thanks for any comments.
Stephen

 

[allanhelen]

Did you set the base idle bridging Gnd and 10?

I pulled the crossover pipe off set a good base idle, then pulled the bridge, connected the crossover and kept adjusting the stop on the pre charger TB until the idle was stable

When you are happy with this check when you open the post charger TB that none of the couplers suck in at all when you blip the throttle if they do check cable adjustment and maybe tweak the pre charger stop a bit more, for fine adjustment you can use the idle screw on the pre charger tb

It just takes a bit of messing with to get it right but you will know when you have

 

[Grandad]

Hi Martin
As ever, thanks for your help.
Presumably bridging GND and 10 makes the ECU open loop.....are you saying, please, that it is then possible to adjust the idle control valve?
Is this done with a screw in the throttle body? Am asking this because I am at home and the car is in the factory so I can't simply nip out to see if there's an adjustment screw!
Many thanks.
Stephen

 

[allanhelen]

Grd and 10 puts the ECU into a Diagnostic/learning mode

In this mode the ICV does not control idle so the idle is just controlled by the air bleed you set with the screw. The ECU then uses this as the benchmark and uses the ICV to make adjustments for cold running, aircon load, rad fan etc

Set the base idle with the car up to full operating temp

 

[Grandad]

................thanks.