SMBA2003
New Member
- Joined
- Jan 18, 2015
- Messages
- 3
- Reaction score
- 0
- Points
- 0
- Vehicle Year
- 2001
- Make / Model
- Ford
- Engine Size
- 2.5
- Transmission
- Manual
So I've been Lurking around trying different tips on solving this P1506 code and I cant seem to solve it or my Idle problem.
The Engine idles at 900 when stationary, but the main issue is when moving and pushing in the clutch or shifting to neutral, the idle stays or even revs up to 3000 revs. Often it stays there until I slow below around 15mph, such as at a light. And also there is the P1506 AIC over speed code.
I have:
- replaced the AIC (the old one looked fine, didn't seem to be sticking or dirty)
- replaced the PCV and vacuum hose
- When around with carb cleaner checking for vacuum leaks, but no leaks as far as I can tell. All hoses look great.
- Tested the TPS (around .9v at idle, 4.8v ish at WOT) which is fine from what I'v read
- Tested EGR valve by applying vacuum to it, and seeing if it stalled the engine (which it did) so I know at least it can open.
I checked mode 6 with OBD II scanner and Torque app.
all normal except :
TID:$10 CID:$21
-
Max: 64
Test result value: 65,535
FAIL
----
TID:$41 CID:$11
-
Min: 64,640
Test result value: 48
FAIL
----
TID:$41 CID:$12
-
Max: 896
Test result value: 48
PASS
I believe there is no Bank 2 o2 sensor, and 65,535 is the highest return possible, so I am ignoring that.
$41 relates to DPFE sensor. CID $12 and $11 relate to the upstream and downstream pressure reading (I forget which is which) but it seems like they shouldn't have the same reading.
- DPFE sensor replaced
Idle issue seems better, but haven't driven enough to be certain. P1506 reappears after clearing computer.
Mode 6 gives new reading:
TID:$41 CID:$11
-
Min: 64,785
Test result value: 65,523
PASS
----
TID:$41 CID:$12
-
Max: 751
Test result value: 65,523
FAIL
65,523 is a max readout so maybe the sensors need to recalibrate?
On another note, unplugging the AIC eliminates the Idle issue, so its not stuck open (as expected, since stationary idle is normal)
From what I understand, the computer is programmed to keep the idle higher by opening the AIC after shifting out of gear to allow for easier shifting and emissions. My hypothesis is that the computer is sending inappropriate open commands to the AIC because some sensor is is giving a bad readout. This also explains why the idle is normal when stationary, as the computer is programmed to keep idle a little higher when moving, in case I decide to put it back in gear.
So:
AIC closed when stopped, normal IDLE
AIC commanded to open too much when shifting out of gear.
Sorry for the long post! What causes this? I've seen several posts with similar symptoms but no real solutions.
I'm planning on testing the Mass Airflow Sensor and EGR solenoid with a multimeter, but That doesn't seem very promising.
Is there some other piece of the puzzle I'm missing? Anyone seen this before? Any help would be great!
The Engine idles at 900 when stationary, but the main issue is when moving and pushing in the clutch or shifting to neutral, the idle stays or even revs up to 3000 revs. Often it stays there until I slow below around 15mph, such as at a light. And also there is the P1506 AIC over speed code.
I have:
- replaced the AIC (the old one looked fine, didn't seem to be sticking or dirty)
- replaced the PCV and vacuum hose
- When around with carb cleaner checking for vacuum leaks, but no leaks as far as I can tell. All hoses look great.
- Tested the TPS (around .9v at idle, 4.8v ish at WOT) which is fine from what I'v read
- Tested EGR valve by applying vacuum to it, and seeing if it stalled the engine (which it did) so I know at least it can open.
I checked mode 6 with OBD II scanner and Torque app.
all normal except :
TID:$10 CID:$21
-
Max: 64
Test result value: 65,535
FAIL
----
TID:$41 CID:$11
-
Min: 64,640
Test result value: 48
FAIL
----
TID:$41 CID:$12
-
Max: 896
Test result value: 48
PASS
I believe there is no Bank 2 o2 sensor, and 65,535 is the highest return possible, so I am ignoring that.
$41 relates to DPFE sensor. CID $12 and $11 relate to the upstream and downstream pressure reading (I forget which is which) but it seems like they shouldn't have the same reading.
- DPFE sensor replaced
Idle issue seems better, but haven't driven enough to be certain. P1506 reappears after clearing computer.
Mode 6 gives new reading:
TID:$41 CID:$11
-
Min: 64,785
Test result value: 65,523
PASS
----
TID:$41 CID:$12
-
Max: 751
Test result value: 65,523
FAIL
65,523 is a max readout so maybe the sensors need to recalibrate?
On another note, unplugging the AIC eliminates the Idle issue, so its not stuck open (as expected, since stationary idle is normal)
From what I understand, the computer is programmed to keep the idle higher by opening the AIC after shifting out of gear to allow for easier shifting and emissions. My hypothesis is that the computer is sending inappropriate open commands to the AIC because some sensor is is giving a bad readout. This also explains why the idle is normal when stationary, as the computer is programmed to keep idle a little higher when moving, in case I decide to put it back in gear.
So:
AIC closed when stopped, normal IDLE
AIC commanded to open too much when shifting out of gear.
Sorry for the long post! What causes this? I've seen several posts with similar symptoms but no real solutions.
I'm planning on testing the Mass Airflow Sensor and EGR solenoid with a multimeter, but That doesn't seem very promising.
Is there some other piece of the puzzle I'm missing? Anyone seen this before? Any help would be great!