APPS Calibration Question
08-30-2018, 10:13 PM
#1
Registered User
Thread Starter
APPS Calibration Question
I installed my new Timbo APPS sensor this evening . When I checked the voltage before calibration , it was bouncing between .65 & .66. So I started turning turning the screw , it almost bottomed out before the voltage went to .67 -.68 . So I turned the screw back half turn and it was showing .7-.71 . So I backed it off a few turns and tried a few more times. I think I might have got it , so I did the APPS reset and truck started and was idling at about 820 rpm . I don’t mind trying again , if someone has some advice for me . Thanks for reading .
08-31-2018, 05:06 AM
#2
Registered User
It may well be that you have the adjuster still turned in too far- there is an idle validation switch that tells the engine to idle (at the idle speed set in the ECM software)- if the idle switch is open, the ECM interprets the voltage from the APPS as "the driver's desire" .
If the APPS does not go low enough to have the idle validation switch activated (like adjuster turned in too far) the APPS reset procedure will not work.
The APPS procedure works like that: A new boot of the ECM (after power outage long enough to shut the ECM down)- A signal "Ignition on, but no start" - the idle validation switch is on- Now the ECM starts the APPS calibration routine.
It watches the APPS voltage, while you move the pedal it records the voltage when the idle validation switch opens , continues to watch the voltage until peak is reached, records the peak, watches the voltage fall and records the value where the idle validation comes back on.
The difference between the low voltage when the IVS goes off and the peak voltage is then split into "load percents" - meaning the ECM knows what the driver wants to signal with the go pedal.
HTH
Markus
If the APPS does not go low enough to have the idle validation switch activated (like adjuster turned in too far) the APPS reset procedure will not work.
The APPS procedure works like that: A new boot of the ECM (after power outage long enough to shut the ECM down)- A signal "Ignition on, but no start" - the idle validation switch is on- Now the ECM starts the APPS calibration routine.
It watches the APPS voltage, while you move the pedal it records the voltage when the idle validation switch opens , continues to watch the voltage until peak is reached, records the peak, watches the voltage fall and records the value where the idle validation comes back on.
The difference between the low voltage when the IVS goes off and the peak voltage is then split into "load percents" - meaning the ECM knows what the driver wants to signal with the go pedal.
HTH
Markus
08-31-2018, 09:18 AM
#3
Registered User
Thread Starter
Thanks Alpine, So if I redo the procedure , how far should i back the screw out before I start turning in? . Before I started turning the screw ( as factory set ) the head was kinda flush with the plate reading .65-.66 ..... after attempting those times , I even tried backing the screw out so half the screw was out and the voltage didn’t go any lower . Now if I try again , where do I start the screw ? I guess I’m asking , if one was to replace their idle screw , how do you set up from there? That’s where I feel I am right now . 
09-01-2018, 05:13 PM
#4
Registered User
Well, in my opinion you can simply test for the idle validation switch changing continuity- this should be right when the pedal moves the lever from the idle stop.
Then do an APPS reset.
Then do an APPS reset.
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