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p1514 truck wont idle, need ideas.


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Vehicle 2002 GMC Sierra Denali 6.0 V8

Electronic throttle, no IAC.

Engine will not idle or start with out depressing the accelerator, when its is running it has to be above 1500RPMs. Seems like the truck is being starved for oxygen, exhaust smells super rich after running for a minute at higher RPMS. The only codes I could pull were p1514 and p0300.

 

P1514 seems to be GMC:Airflow to TP Sensor Correlation High.

I checked the Throttle body and it was relatively clean (functions with the go pedal), I went ahead and cleaned it all out. I also verified power to MAF I did try to run the truck with the MAF unplugged and didn’t notice any improvement. Before the truck died on the road it seemed to be working fine, it just shut off in traffic…

 

any suggestions where to go from here?

no reduced engine power messages

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P1514 2002 GMC SIERRA DENALI V8 6

MAF Sensor Performance

– The PCM detects that the difference between the actual airflow (MAF) and the Speed Density calculated air flow is greater than expected

Probable Cause

  • Poor connection at the TAC module
  • Failed TAC module
  • Check TPP or TPS sensors
  • Binding or bent throttle plate-failed throttle body
  • Faulty MAF

 

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P1514 2002 GMC SIERRA DENALI V8 6

MAF Sensor Performance

– The PCM detects that the difference between the actual airflow (MAF) and the Speed Density calculated air flow is greater than expected

Probable Cause

  • Poor connection at the TAC module (I'll check this)

     

  • Failed TAC module

     

  • Check TPP or TPS sensors (shouldnt this throw another code?)

     

  • Binding or bent throttle plate-failed throttle body (appears to be functioning)

     

  • Faulty MAF (shouldnt this throw another code? vehicle should run ~ normally if MAF is unplugged. this was not the case in my checking)

     

 

 

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had something similar happen on an '02, it was a vacuum line that had come loose. I would check your vacuum lines, your O2 sensor connections, even your gas cap. Do you have an aftermarket air filter? If you do and it was oiled too much it will contaminate your MAF and mess up the calibration...

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vehicle doesnt run...so would have to be towed. Currently low enough on funds that i cant justify taking it in...and typically im capable of fixing the problems my vehicles have encountered.

 

What would they do, to better analyze the problem?

 

 

unfortunately in your case ,you will opt out for a diagnoses and throw parts at it until its fixed (which pays for diagnoses),Assumptions on description and operation without researching and reading in service information, Alldata for example will pull you further away from the actual problem,

 

good luck ,your gonna need it

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vehicle doesnt run...so would have to be towed. Currently low enough on funds that i cant justify taking it in...and typically im capable of fixing the problems my vehicles have encountered.

 

What would they do, to better analyze the problem?

 

 

may have defective ECM, try to reset it by take battery cable out

 

your engine is still good, but electronics have some issues and that's why when you slam on the gas its run

 

P1514 = your engine suck more air than fuel, because the ECM is going crazy, then your throttle position is wrong - so this could be due to bad capacitors in ECM

 

do you think you can fix this?, if Yes

 

then remove the ECM and check all caps with ESR meter

 

ohh one more test try blocking air intake with a big rag or something (don't choke all the way), truck should idle.

 

look for broken wires, loose connection etc, if everything is good - but truck won't run, time to buy a new or reman ECM

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DTC P1514

 

Circuit Description

 

The powertrain control module (PCM) uses the following readings in order to calculate the predicted mass air flow (MAF) rate:

 

 

 

 

 

 

 

 

 

 

 

 

The PCM compares the predicted MAF value to the actual MAF value, and to the speed density calculation in order to verify the proper throttle operation.

Conditions for Running the DTC

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Conditions for Setting the DTC

 

 

 

 

 

 

Action Taken When the DTC Sets

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Conditions for Clearing the MIL/DTC

 

 

 

 

 

 

 

 

 

 

 

 

Diagnostic Aids

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Test Description

 

The numbers below refer to the step numbers on the diagnostic table.

5 This step will determine if the manifold absolute pressure (MAP) sensor voltage is within the proper range at idle.

 

 

6 This step will determine if the MAP sensor responds properly to the change in manifold pressure.

 

 

7 A throttle blade that sticks or binds may set this code. Opening the throttle through the entire range will indicate problems such as these.

 

 

9 When the PCM detects a condition within the ETC system other DTCs may set due to the many redundant tests run continuously on this system. Locating and repairing 1 individual condition may correct more than 1 DTC. Keep this in mind when reviewing captured DTC info.

 

Step

 

 

 

Action

 

 

 

Values

 

 

 

Yes

 

 

 

No

 

 

 

Schematic Reference: Engine Controls Schematics

 

Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views

 

 

1

 

 

Did you perform the Diagnostic System Check–Engine Controls?

 

 

 

 

Go to Step 2

 

 

Go to Diagnostic System Check - Engine Controls

 

 

2

 

 

Are any other DTCs set?

 

 

 

 

Go to Diagnostic Trouble Code (DTC) List

 

 

Go to Step 3

 

 

3

 

 

 

 

 

 

 

 

 

 

 

Did the DTC fail this ignition?

 

 

 

 

Go to Step 4

 

 

Go to Diagnostic Aids

 

 

4

 

 

Inspect for the following conditions:

 

 

 

 

 

 

Did you find and correct the condition?

 

 

 

 

Go to Step 8

 

 

Go to Step 5

 

 

5

 

 

 

 

1. Allow the engine to reach operating temperature.

 

 

 

2. Observe the MAP sensor voltage parameter with a scan tool.

 

 

Is the MAP sensor voltage within the specified range?

 

 

0.8–4?V

 

 

Go to Step 6

 

 

Go to DTC P0106

 

 

6

 

 

 

 

1. Idle the engine.

 

 

 

2. Observe the MAP sensor kPa parameter with a scan tool.

 

 

 

3. Increase the engine speed slowly and then back to idle.

 

 

Does the MAP sensor kPa change smoothly and gradually as engine speed is increased and returned to idle?

 

 

 

 

Go to Step 7

 

 

Go to DTC P0106

 

 

7

 

 

 

 

 

Caution: Turn OFF the ignition before inserting fingers into the throttle bore. Unexpected movement of the throttle blade could cause personal injury.

 

 

 

 

1. Inspect the throttle body for the following conditions while modulating the throttle through the entire range using the scan tool:

 

 

 

• Loose or damaged throttle blade

 

 

 

• Broken throttle shaft

 

 

 

• Drive mechanism damage

 

 

 

2. If any of these conditions exist, replace the throttle body assembly. Refer to Throttle Body Assembly Replacement .

 

Did you find and correct the condition?

 

 

 

 

Go to Step 6

 

 

Go to Diagnostic Aids

 

 

8

 

 

 

 

 

 

 

 

 

 

 

Did the DTC fail this ignition?

 

 

 

 

Go to Step 2

 

 

Go to Step 7

 

 

<a href="http://gsi.xw.gm.com/newsi/showDoc.do?laborOpCode=&docSyskey=758936&cellId=30532&pubObjSyskey=4587628&from=sm&pubCellSyskey=994056#td09">9

 

 

Observe the Capture Info with a scan tool.

 

Are there any DTCs that have not been diagnosed?

 

 

 

 

Go to Diagnostic Trouble Code (DTC) List

 

 

System OK

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exactly my point

 

 

+1

 

you must have Tech2 scantool + know how to use it methodically

 

else you can blindly swap ECM from rack yard, just to test

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