Dawes and Needle Valve?

[Chaz]

Hi E.T.

I definitely don’t baby the ZD30. I like to get it up on boost ASAP and keep it in the zone (so to speak) which is normally between 10 and 12psi in my case, unless I get off the throttle. I have a 2 stage system which is limited to around 14psi until I hit 1.6v TPS and then it goes up to 16psi. Doing anything above 100km/h usually invokes 16psi.

The Patrols EGR system has 3 stages of “open” and to my knowledge it’s only closed when the engine is idling cold and at full throttle. I may be wrong here, but I was lead to believe that it’s still open with a fairly heavy throttle, which is why we see boost drop with the factory system even when we accelerate. Maximum EGR is acheived under some load when combustion temps are the highest. Which is why we bypass the ECU control solenoid and fit a manual TDi controller after blocking the EGR - to overcome the ECU dropping boost unnecessarily.

[the evil twin]

Hi Chaz,

Yeah, I drive mine in a reasonably similar manner.

EGR control wise... I didn't realise the Di's and CRD's were as different as they are but something doesn't gel.

You mention the EGR on the Di's only has 3 positions which was my understanding as well but I've not had one so hadn't paid much attention until I started delving into the manuals.

From the Factory manual page EC-238... SM9E-Y61CG3 (July 99) the Di's have a DC stepper motor (unless the aussie ones are different which has been known to happen).

This system controls flow rate of EGR led from exhaust manifold
to intake manifold. The opening of the EGR by-pass passage in the
EGR volume control valve changes to control the flow rate. A
built-in step motor moves the valve in steps corresponding to the
ECM output pulses. The opening of the valve varies for optimum
engine control. The optimum value stored in the ECM is determined
by considering various engine conditions


From the Factory manual page EC-236... SM9E-Y61KG3 (Jan '07) the stepper motor is gone in the CRD's and a DC motor and feedback control loop used and this is indeed how my CRD appears to be set up from what I can see as the EGR Volume Control is buried in the bowels. I soooo wish I'd paid more attention when I put the block in...

The opening of the EGR
passage in the EGR volume control valve changes to control the EGR flow rate. A built-in DC motor moves the
valve continuously corresponding to the ECM output signal. The EGR volume control valve control position sensor
detects the valve position and sends the voltage signals to the ECM. The ECM judges the current opening
angle of the valve from this signals and the ECM controls the DC motor to make the valve opening angle properly.
The opening of the valve varies for optimum engine control..

Dunno if we are wandering off topic or not but IMHO the above would be related to MBC setups anyway depending on EGR blocking