Bosch 3 wire 0280140578 and Min/Max clamp setting

[R24]

Hi guys, can anyone confirm if the Bosch 3 wire icv is a solenoid or stepper motor type? I read a few post and some term it as a solenoid and some call it stepper.

For the max clamp and min clamp settings, how do we set it?  According to help file, they are 2 method mentioned, eg. Max value is the highest idle base plus all idle up values and on another page it says that it should be set 10% more than the highest idle base value.

Same goes to min clamp, the help file says should be 10% less than the lowest idle base value and on the setup procedure it was mentioned we should enter the lowest value as in the idle base. Any idea anyone?

[Adamw]

This is not a valve I have seen before but I would expect with three wires it would have to be a solenoid valve.  A Stepper usually needs 4 or 6 wires.  Start with the min & max clamps set to 0 & 100% then set the clamps properly after you have tuned the base position table.

[R24]

Hi Adam, for the min clamp setting, should I minus 10% from the lowest idle base numbers or maintain it same as the idle base numbers? Can it be set at the value when the valve is fully closed?

[Simon]

It would normally be the DC that causes the valve to be fully closed.

[R24]

Yes Simon im aware of that. But can you give me a situation if the min clamp is not set properly? Im having 29 dc as my lowest settings in IBP table and a 10% for min clamp. Should the min clamp number be the same as when i lower the dc steps, the valve stays half closed for example?

[Simon]

A typical situation would be that if the min clamp is to low, the ECU will be reducing the idle by lowering the DC. It will work fine down to say 30% but as you drop below 30% the valve starts to open again getting more open as you reduce the DC which causes the idle to increase and the ECU pulls even more.

If the solenoid is full closed at 0% DC then there is no issue with a 0 clamp its only in cases where the valve starts to open at lower DC.

[R24]

So in this case is it safe to say that the min clamp be set 10% lower than the min idp like in the setting menu? Or the setting will depend with the type of idle valve used?

I have intermittent engine stall after old start up let say around 70 °c. This happens when i press the brake slowing down depressing the clutch. 

[Simon]

Do you have a speed lock out set up for the idle speed control? 

You also want to have the main butterfly open enough that the engine will idle at a lowish RPM even when the ISC is 100% closed.

But a min clamp could also help too as it will limit the amount the valve can close 

[R24]

Yes I have, my rpm lockout is at 1500, map at 60 and speed lockout at 2kph.

I have a rough idea now about the set up. Let me check the butterfly valve as how far it is open. What you suggest for the opening, a tp of 1%?

[Simon]

Just enough to let the motor sit at a low idle with no load on it. It will be a case of trial and error.

[R24]

Sure ill try that maybe at 500 to 600 rpm. Ill get back to you once I get my results. Thanks Simon. Oh on another note, by altering the butterfly opening the ibp table values from 70,80 and 90 will need to be adjusted too if im right?

[Simon]

Yep they likely will and be sure to respan the TPS

[R24]

Well Simon. I tried to open up the throttle plate at hot idle, zeroing the ibp table, fan step and steering step. My car doesn't hold the idle at 500 or 600 rpm and the lowest I can hold is 700rpm +. Even though i got that, my ibp table needs some very low dc steps to reach target. Example from 30dc@80°c to 15dc.

Another thing I found out is the isc valve doesn't have any adjustment screw to maintain the dc to 50( as i read someone wrote in their post) to maintain a good idle. 

Do we really need the dc to be maintained more than 40 at any point of time during idle? What is the lowest value we can go to maintain proper idle and not stalling during coasting or braking to stop?

[Adamw]

1 hour ago, R24 said:

Do we really need the dc to be maintained more than 40 at any point of time during idle?

No, provided the valve still changes the idle speed when you change DC then it will be fine left as it is.  Some valves for instance will not close any further once you go below 25% DC, so if you can still bump idle up or down by changing the commanded DC when you are down at say 15% then it sounds like it is fine to leave it as is.

[R24]

1 hour ago, Adamw said:

so if you can still bump idle up or down by changing the commanded DC when you are down at say 15% then it sounds like it is fine to leave it as is.

So either way, its best to check manually at which dc value the particular valve closes max and min to determine the value for the idle base.

Does the altezza g4+ ecu has rev matching function?

I'll do few more test and update soon.