High Idle, high RPM in neutral while at speed
November 7th, 2012, 1:16 PM
#11
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November 7th, 2012, 4:05 PM
#12
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November 7th, 2012, 4:47 PM
#13
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I don't know for certain but here is my edumacated guess
most likely..
The motor that controls the throttle has an encoder that tells the ECM where it is from a known position or "home" It remembers that location from the last know good power on condition.
At the next power up it does a checksum, and compares the saved value of the last known good position to the "what is it now position", if they don't match then it tells the ECM that something has changed and a "relearn" is in order...
At no point did I ever get any SES notice, so I guess its something that has a certain amount of error built in so if its within a given range its " I just need to relearn" if its outside that range it flags it and sends out an SES alert..
most likely..
The motor that controls the throttle has an encoder that tells the ECM where it is from a known position or "home" It remembers that location from the last know good power on condition.
At the next power up it does a checksum, and compares the saved value of the last known good position to the "what is it now position", if they don't match then it tells the ECM that something has changed and a "relearn" is in order...
At no point did I ever get any SES notice, so I guess its something that has a certain amount of error built in so if its within a given range its " I just need to relearn" if its outside that range it flags it and sends out an SES alert..
November 8th, 2012, 8:59 AM
#15
CF Active Member
AhHa! reading is fundamental
...
Attached to the throttle body cleaning is...Throttle Learn
2007 Chevrolet Tahoe - 2WD | Avalanche, Escalade, Suburban, Tahoe, Yukon (VIN C/K) Service Manual | Document ID: 1820246
--------------------------------------------------------------------------------
Throttle Learn
Description
The engine control module (ECM) learns the idle position of the throttle plate to ensure the correct idle. Anytime the throttle body is cleaned or replaced, the ECM must learn the new throttle position. The idle may be unstable or a DTC may set if the throttle position is not learned.
Conditions for Running the Throttle Learn Procedure
DTCs P0101, P0102, P0103, P0107, P0108, P0111, P0112, P0113, P0506, and P0507 are not set.
The engine speed is between 450-4,000 RPM.
The manifold absolute pressure (MAP) is greater than 5 kPa.
The mass air flow (MAF) is greater than 2 g/s.
The ignition 1 voltage is greater than 10 volts.
Throttle Learn
Important: Do NOT perform this procedure if DTCs are set. Refer to Diagnostic Trouble Code (DTC) List - Vehicle .
Start and idle the engine in PARK for 3 minutes.
With a scan tool, monitor desired and actual RPM.
The ECM will start to learn the new idle cells and Desired RPM should start to decrease.
Ignition OFF for 60 seconds.
Start and idle the engine in PARK for 3 minutes.
After the 3 minute run time the engine should be idling normal.
Important: During the drive cycle the check engine light may come on with idle speed DTCs. If idle speed codes are set, clear codes so the ECM can continue to learn.
⇒ If the engine idle speed has not been learned the vehicle will need to be driven at speeds above 70 km/h (44 mph) with several decelerations and extended idles.
After the drive cycle, the engine should be idling normally.
⇒ If the engine idle speed has not been learned, turn OFF the ignition for 60 seconds and repeat step 6.
Once the engine speed has returned to normal, clear DTCs.
...Attached to the throttle body cleaning is...Throttle Learn
2007 Chevrolet Tahoe - 2WD | Avalanche, Escalade, Suburban, Tahoe, Yukon (VIN C/K) Service Manual | Document ID: 1820246
--------------------------------------------------------------------------------
Throttle Learn
Description
The engine control module (ECM) learns the idle position of the throttle plate to ensure the correct idle. Anytime the throttle body is cleaned or replaced, the ECM must learn the new throttle position. The idle may be unstable or a DTC may set if the throttle position is not learned.
Conditions for Running the Throttle Learn Procedure
DTCs P0101, P0102, P0103, P0107, P0108, P0111, P0112, P0113, P0506, and P0507 are not set.
The engine speed is between 450-4,000 RPM.
The manifold absolute pressure (MAP) is greater than 5 kPa.
The mass air flow (MAF) is greater than 2 g/s.
The ignition 1 voltage is greater than 10 volts.
Throttle Learn
Important: Do NOT perform this procedure if DTCs are set. Refer to Diagnostic Trouble Code (DTC) List - Vehicle .
Start and idle the engine in PARK for 3 minutes.
With a scan tool, monitor desired and actual RPM.
The ECM will start to learn the new idle cells and Desired RPM should start to decrease.
Ignition OFF for 60 seconds.
Start and idle the engine in PARK for 3 minutes.
After the 3 minute run time the engine should be idling normal.
Important: During the drive cycle the check engine light may come on with idle speed DTCs. If idle speed codes are set, clear codes so the ECM can continue to learn.
⇒ If the engine idle speed has not been learned the vehicle will need to be driven at speeds above 70 km/h (44 mph) with several decelerations and extended idles.
After the drive cycle, the engine should be idling normally.
⇒ If the engine idle speed has not been learned, turn OFF the ignition for 60 seconds and repeat step 6.
Once the engine speed has returned to normal, clear DTCs.
Very good indeed.I overlooked the fact that your 07' model is a "fly by wire" throttle assembly.
Us guys with the older trucks still have the cable and the "slow" ECM
November 8th, 2012, 1:14 PM
#16
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Thread Starter
I'm going to have to go with a YES* on that one...
I performed the "let it run for 3 minutes in park" yesterday but did not drive anywhere afterward. I took her out this morning for a 64 mile round trip.
*RPM at idle in drive is about 525 , that is pretty normal.
However, I'm still not seeing the Instant economy of 99 mpg in V4 while costing, its now reaching into the 80's but it is getting there, when I first did the TB clean and noticed the higher RPM's it was only in the 60's
As for shifting into neutral while at speeds and the RPM's rising, that is hit or miss. below 50 mph it seems to drop.. above 55 mph it revs to 2100 rpm, I pulled over and could hear it rev'ed while stopped and after a few seconds it dropped to normal... that is a little strange
Here is a drive cycle monitor... what I found interesting is the Alcohol listed at 20%
MIL STATUS OFF
MIL STATUS OFF
ABSLT TPS % 16.4
ENG SPEED RPM 523
BARO PRS KPA 99
CALC LOAD % 18.4
MAF FLOW GR/SE 5.63
MAP KPA 37
OUT TEMP F 80
COOLANT F 194
IAT F 91
IGN ADVANCE DE 15.0
ST FTRM1 % 0.0
LT FTRM1 % -11.8
ST FTRM2 % -3.4
LT FTRM2 % -13.3
VEH SPEED MPH 0
ABSLT LOAD % 20.0
FUEL SYS 1 CLSD
FUEL SYS 2 CLSD
ALCOHOL % 20.7
REL TPS % 2.7
THROT CMD % 3.9
ABS TPS B % 16.8
ACC POS D % 18.8
ACC POS E % 9.0
CAT TEMP11 F 1004
CAT TEMP21 F 968
EVAP PURGE % 16.4
EVAP VP H2O 0.000
CMD EQ RATIO 0.999
O2S11 V 0.175
ST FTRM11 % 0.0
O2S12 V 0.775
O2S21 V 0.055
ST FTRM21 % 0.0
O2S22 V 0.750
CLR DIST mi 143
CLR DIST mi 96
CLR TRPS 1450
CLR TRPS 1450
MIL DIST mi 0
MIL DIST mi 0
FUEL LEVEL % 41.9
VPWR V 0.049
VPWR V 0.074
ENG RUN m:s 13:11
OBD2 STAT CA/US
I performed the "let it run for 3 minutes in park" yesterday but did not drive anywhere afterward. I took her out this morning for a 64 mile round trip.
*RPM at idle in drive is about 525 , that is pretty normal.
However, I'm still not seeing the Instant economy of 99 mpg in V4 while costing, its now reaching into the 80's but it is getting there, when I first did the TB clean and noticed the higher RPM's it was only in the 60's
As for shifting into neutral while at speeds and the RPM's rising, that is hit or miss. below 50 mph it seems to drop.. above 55 mph it revs to 2100 rpm, I pulled over and could hear it rev'ed while stopped and after a few seconds it dropped to normal... that is a little strange
Here is a drive cycle monitor... what I found interesting is the Alcohol listed at 20%
MIL STATUS OFF
MIL STATUS OFF
ABSLT TPS % 16.4
ENG SPEED RPM 523
BARO PRS KPA 99
CALC LOAD % 18.4
MAF FLOW GR/SE 5.63
MAP KPA 37
OUT TEMP F 80
COOLANT F 194
IAT F 91
IGN ADVANCE DE 15.0
ST FTRM1 % 0.0
LT FTRM1 % -11.8
ST FTRM2 % -3.4
LT FTRM2 % -13.3
VEH SPEED MPH 0
ABSLT LOAD % 20.0
FUEL SYS 1 CLSD
FUEL SYS 2 CLSD
ALCOHOL % 20.7
REL TPS % 2.7
THROT CMD % 3.9
ABS TPS B % 16.8
ACC POS D % 18.8
ACC POS E % 9.0
CAT TEMP11 F 1004
CAT TEMP21 F 968
EVAP PURGE % 16.4
EVAP VP H2O 0.000
CMD EQ RATIO 0.999
O2S11 V 0.175
ST FTRM11 % 0.0
O2S12 V 0.775
O2S21 V 0.055
ST FTRM21 % 0.0
O2S22 V 0.750
CLR DIST mi 143
CLR DIST mi 96
CLR TRPS 1450
CLR TRPS 1450
MIL DIST mi 0
MIL DIST mi 0
FUEL LEVEL % 41.9
VPWR V 0.049
VPWR V 0.074
ENG RUN m:s 13:11
OBD2 STAT CA/US
November 8th, 2012, 4:55 PM
#18
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Thread Starter
I do need to do some reading up on it as I buy Shell regular and it does have the sticker that says "May contain up to 10% Ethanol"
But I don't understand why it reads 20% ? this particular tank of gas I didn't add any Techron to...
But I don't understand why it reads 20% ? this particular tank of gas I didn't add any Techron to...
November 9th, 2012, 1:50 PM
#19
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I have read that both the refinery has added 10% and then the distributer added 10% after they received it. That way they both received their govt subsidies. Could happen.
November 12th, 2012, 5:22 PM
#20
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Took a trip down to Galveston this weekend and the road trip has everything back to normal :-) even coasting at highway speeds I get the instant economy of 99mpg in V4 :-) averaged about 20.5mpg going down and 19.4mpg coming back with the cold front headwind. Kept to speed limit or 5 mph less...