Idle Control Valve Query

[Steve Medlock]

A while ago, I was having idle problems which seemed to be cured by fitting a second hand MAF. However I thought I would check the idle control valve when I had time an so this afternoon I gave it a good clean with carb cleaner and also replaced the rubber gromit and hose. It wasn't seized but did move much more freely after the clean up.

After a run, I plugged INPA in to check for fault codes and found none. The analogue 1 values don't look right though!

I don't know what engine load is but on a scale of 0-7 its 113...

The idle control valve on a scale of 0-10 would only go down as low as about 11 at best. Confusingly, it increases when I open the throttle whereas I was expecting it to be zero or closed?

Can anyone tell me what's going on here please?

 

[colb]

Found this explanation on Engine Load on this forum site https://www.eng-tips.com/viewthread.cfm?qid=381272
Made sense to me when I read it.

"I wonder if the original poster is referring to the parameter that the on-board-diagnostics call "load", if you are watching the engine parameters with a Scangauge or other such tool.

That "load" is more-or-less the percentage of air/fuel delivery going through the engine relative to what it would be at wide-open-throttle (100% "load").

It's not unusual for "load" to be reported in the 25% - 30% range with the engine idling in neutral (zero "actual load" being output), because that's how much it's taking to spin the engine to overcome friction, oil pumping, water pumping, throttling, etc.

The fuel injection system uses this to calculate the correct amount of fuel delivery and also
the correct ignition timing, variable-valve-timing actuation (where so equipped), etc.

It is correlated to the output torque, but not directly so."

 

[colb]

I did notice the coolant temp on your screen shot was low at 69.75C, was this because you hadn't let the car reach full temp when you took the screen shot, thought it would be best to compare the data when the engine is at full operating temp.

 

[Steve Medlock]

I did notice the coolant temp on your screen shot was low at 69.75C, was this because you hadn't let the car reach full temp when you took the screen shot, thought it would be best to compare the data when the engine is at full operating temp.

Ah that's because I went out again a bit later to get a screen print after the engine had cooled some. It didn't seem to affect the ICV readings though.

I sort of understood the engine load although INPA seems to be doing it quantitatively rather than as a %age. I wonder why the INPA scales for these two parameters aren't more in line with the range of possible readings?

As far as the ICV is concerned though, I thought this was basically to supply air to the engine when the throttle is closed so it can idle. The 'air use' seems to go up as the throttle is opened though.

Anyone got a similar print out for their own car perhaps?

 

[NZ00Z3]

The 6 cylinder engine ICV operates (opens) up to around 2,500 rpm. The throttle body has little impact on the air control until around 2,000 rpm. That why the ICV was still opening when you blipped the throttle.

 

[Steve Medlock]

Just found some M52/INPA Youtube videos - looks like these readings are normal!

 

[Steve Medlock]

The 6 cylinder engine ICV operates (opens) up to around 2,500 rpm. The throttle body has little impact on the air control until around 2,000 rpm. That why the ICV was still opening when you blipped the throttle.

Thanks Murray - that's most helpful to know.