Recorded Grille Shutter Commanded Operation with FORScan

[plus 3 golfer]

Here's recorded operating data on the grille shutters from my recent trip .  There were over 102 k observation taken with rising ambient air temperature from 81 F to 93 F over nearly 58 minutes with AC on.  The data was recorded traveling I-20 W starting between Weatherford TX and Abilene TX. Although I couldn't record Transmission Fluid Temperature with the current release of FORScan at the same time with grille shutter data, I can say that when recording TFT under similar driving conditions, TFT was never above 176 *F.  TFT usually stayed around 30F under Engine Coolant Temperature which means TFT usually ran between about 155-165*F.  I have to review more recorded data and may start another thread on it.

 

"The grille shutter moves 90 degrees from fully closed to fully open and based on the position commanded by the PCM is set in 1 of 16 positions (approximately 6 degrees between positions)...."The PCM communicates the desired position (open or closed) of the grille shutter based on various PCM inputs (vehicle speed, coolant temperature, ambient temperature, A/C system pressure, etc.). "

 

The first graph shows four of the variables recorded.  The PIDs are:

 

GRILL_A_CMD (%) -  This is the commanded opening % for the grill shutters.  There is also an inferred grill shutter open % PID also.  I assume this is a sensor reporting back to the PCM.  The inferred position tracks the commanded opening but can be a few % points slightly higher or lower than the commanded positions.  I assume this is because the shutters move in steps of about 6.7% (6*/90*).

 

ECT(°F)  - Engine Coolant Temperature.

 

AAT(°F) - Ambient Air Temperature

 

VSS(mph) - Vehicle Speed Sensor   

 

 

A couple of observation were noted:1) there was a correlation between commanded position and ambient air temperature and 2) speed affected commanded position.

 

The next graph shows commanded position vs speed above 60 mph.  I also graphed (with trend line) for speeds above 70 mph and for speeds above 50 mph.  The trend line equation for above 70 mph was virtually the same as above 60 mph.  But, for the trend line equation for above 50 mph correlation dropped.  R^2 dropped to 82% (from 87% for data above 60%)and the slope dropped from the 0.99 (virtually one degree ambient temperature change equaled one percent change in commanded shutter position for speeds above 60 mph) to 0.95. So, It appeared from the first graph that speed was having more of an influence on shutter position under 50 mph (minutes 13 to about 15 on first graph).

 

So, I graphed speed under 50 mph vs grille shutter position shown in the last graph.  The graph clearly shows that speed is likely the driving variable to shutter position under 50 mph with AC on with the ambient temperatures being experienced. 

 

 

[ptjones]

Plus 3 Golfer when I checked shutters a while ago shutters were always open with the A/C on.  Also when I did my FWY video test the shutters would open at 215*F WT and close at 214*F WT going 65-70 mph.  At 50 mph the shutters opened 210*F WT.  I will have to look to see if I can record this some how. :)

 

Paul

[plus 3 golfer]

When I turn the AC off, the shutter cmd PID immediately drops to 0% to close the shutters. The shutter inferred PID drops to zero in steps and takes seconds to reach zero. I don't recall whether I captured that on my recent trip but next time out I'll cycle AC on and off and record it.

 

When I turn the AC back on, shutter cmd immediately jumps to a point along the curves in the graph. The inferred shutter PID steps up over several seconds to near the shutter cmd PID.

 

In both cases IIRC one can see that ECT has a delayed reaction to whether AC is on or off. ECT goes up with AC off over what it was with AC on and down with AC on o er AC off all other things being the same.

[plus 3 golfer]

Here's my post of when I observed shutter operation with a camera over 2 years ago.  With AC off ECT is higher.  ECT ran between about 195 F and 212 F.  As noted in the post, shutters could be closed at 195 F and in various stages of opening up to 212 F.  I did not use grille covers in this test.  I will shortly run test with AC off at high speeds and record the data.

 

As I've said before I will not use grille covers when I run the AC.  Here's my post about my summer 2013 trip and monitoring ECT.

 

I see consistent operation of the grille shutter in this post and the my other linked posts. 

Edited August 2, 2015 by Plus 3 Golfer

[plus 3 golfer]

Here's another graph showing grille shutter operation.  I hope this clears up how the shutters operate when AC is ON and when AC is OFF.   As I look at more data streams and if I find anything interesting, I will graph it.

 

Note that this graph is with ambient temperature around 82 F.  I believe this operation is indicative of grille shutter operations at lower and higher ambient temps.  I have recorded operation as low as 68 F ambient and as high as 106 F (IIRC).   I should also note that there are no grille covers on.  I should also note that somewhere around 212 - 214 ECT, the grille shutters are fully open but the shutters can be partially open at ECT temps below 212 F (note graph).

 

As I've said before, FORscan currently does not support data streaming across modules.  Thus, I can not record TFT at the same time as grille shutter operation.  But I can say that the highest I've recently observed was 180 F when ECT was over 212 F.  Again, when regenerating (not just coasting) but moderately hard braking or using hill assist down steeper grades, I again observed motor coil temps rising about 7 F very quickly and TFT rising about 4 F but delayed.  I have this data recorded and may sometime get to it.  I have yet to see any abnormal behavior with TFT.  In general, TFT are stable and seem to be more dependent on ambient temperature.  Again, I am not using grille covers.