2003 Buick Century please help me!

Tiny
TANK33
  • MEMBER
  • 2003 BUICK CENTURY
2003 Buick Century 6 cyl Automatic 121057 miles

i got computer read, saying map sensor low circuit. So I changed it 1 hour later, check light back on got it read again and said the same thing. I checked for break in the wire(s), corrosion and the plug itself. No signs of anything bad. Now car is running bad skipping you can hear in exhaust manifold and out of exhaust. Will map sensor make car run this way please help thanks
Do you
have the same problem?
Yes
No
Wednesday, February 17th, 2010 AT 9:06 PM

1 Reply

Tiny
FACTORYJACK
  • EXPERT
Yes the map can cause some running problems, running problems can also cause false MAP codes. You have a low voltage code that I assume is a P0107. Low voltage equates to high vacuum, say idle or decel. Typically, when a running problem sets a map code, it goes the other way, as a running problem is often attributed to low vacuum. You have three wires at that sensor, pin A low reference(ground) black wire, pin b light green map signal wire, and pin c 5-volt reference gray wire. The first thing would be to check for 5 volts(or close) with a voltmeter, first to good ground, and then to pin A. If you have five volts there, ask yourself if the fault is happening currently, it could be intermittent. If it does not have five volts, with either ground source, then you would check the gray wire for open from sensor to ECM pin 10 of connector C1(blue). If here is 5 volts with the good ground but not the low ref pin A, it could be the low ref circuit from the MAP sensor to splice S121, beyond that splice the coolant temp shares the lo ref(ground) and you would have issues with that. With that info, you have something to go on. A scan tool that reads data, would simplify matters, especially if this is intermittent. I will paste the trouble code chart for reference:
DTC P0107
Circuit Description
The manifold absolute pressure (MAP) sensor responds to pressure changes in the intake manifold. The pressure changes occur based on the engine load. The MAP sensor has the following circuits:

" 5-volt reference circuit

" Low reference circuit

" MAP sensor signal circuit

The powertrain control module (PCM) supplies 5 volts to the MAP sensor on the 5-volt reference circuit. The PCM also provides a ground on the low reference circuit. The MAP sensor provides a signal to the PCM on the MAP sensor signal circuit which is relative to the pressure changes in the manifold. The PCM should detect a low signal voltage at a low MAP, such as during an idle or a deceleration. The PCM should detect a high signal voltage at a high MAP, such as the ignition is ON, with the engine OFF, or at a wide open throttle (WOT). The MAP sensor is also used in order to determine the barometric pressure (BARO). This occurs when the ignition switch is turned ON, with the engine OFF. The BARO reading may also be updated whenever the engine is operated at WOT. The PCM monitors the MAP sensor signal for voltage outside of the normal range.

If the PCM detects a MAP sensor signal voltage that is excessively low, this DTC will set.

Conditions for Running the DTC
" DTCs P0121, P0122, or P0123 are not set.

" The engine is running.

" The throttle angle is more than 0 percent, if the engine speed is less than 1000 RPM.

Conditions for Setting the DTC
" The MAP sensor signal voltage is less than 0.1 volts (12 kPa).

" Above conditions are present for longer than 200 3X reference periods (67 crankshaft revolutions).

Action Taken When the DTC Sets
" The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.

" The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC
" The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.

" A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

" A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.

" Clear the MIL and the DTC with a scan tool.

Diagnostic Aids
" Inspect the MAP sensor vacuum source for leaks, for restrictions, or for poor connections.

" If the condition is intermittent, refer to Intermittent Conditions.

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

The MAP sensor 5 volt reference circuit is shared with other sensors. If DTC P1635 is set, this indicates that the 5 volt reference circuit is either shorted to ground or shorted to voltage and should be diagnosed first. The short may be on another sensor 5 volt reference circuit.

Operate the vehicle within the same conditions as when the DTC failed. If you cannot duplicate the DTC, the information included in the Freeze Frame and Failure Records data can aid in locating an intermittent condition.

P0107- MAP Sensor Circuit Low Voltage Step
Action
Values
Yes
No

Schematic Reference: Engine Controls Schematics

1
Did you perform the Diagnostic System Check-Engine Controls?
--
Go to Step 2
Go to Diagnostic System Check - Engine Controls

2
Install a scan tool.
Start the engine.
Does the scan tool indicate that DTC P1635 is current?
--
Go to DTC P1635
Go to Step 3

3
With a scan tool, observe the MAP sensor voltage.

Does the voltage measure less than the specified value?
0.1 V
Go to Step 5
Go to Step 4

4
Observe the Freeze Frame and Failure Records data for this DTC.
Turn OFF the ignition for 30 seconds.
Start the engine.
Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text or as close to the Freeze Frame and/or Failure Records data that you observed.
Does the DTC fail this ignition?
--
Go to Step 5
Go to Diagnostic Aids

5
Turn OFF the ignition.
Disconnect the MAP sensor electrical connector.
Connect a DMM between the 5 volt reference circuit of the MAP sensor and a good ground.
Turn ON the ignition, with the engine OFF.
Does the voltage measure near the specified value?
5.0 V
Go to Step 6
Go to Step 7

6
Connect a 3 amp fused jumper wire between the 5 volt reference circuit of the MAP sensor and the signal circuit of the MAP sensor.

Does the scan tool indicate that the voltage is near the specified value?
5.0 V
Go to Step 9
Go to Step 8

7
Test the 5 volt reference circuit of the MAP sensor for a short to ground or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?
--
Go to Step 13
Go to Step 10

8
Test the signal circuit of the MAP sensor for an short to ground or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?
--
Go to Step 13
Go to Step 10

9
Inspect for poor connections at the harness connector of the MAP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?
--
Go to Step 13
Go to Step 11

10
Inspect for poor connections at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?
--
Go to Step 13
Go to Step 12

11
Replace the MAP sensor. Refer to Manifold Absolute Pressure Sensor Replacement.

Did you complete the replacement?
--
Go to Step 13
--

12
Replace the PCM. Refer to Powertrain Control Module Programming.

Did you complete the replacement?
--
Go to Step 13
--

13
Use a scan to clear the DTCs.
Turn OFF the ignition for 30 seconds.
Start the engine.
Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
Does the DTC run and pass?
--
Go to Step 14
Go to Step 2

14
With a scan tool, observe the Stored Information, Capture Info.

Does the scan tool display any DTCs that you have not diagnosed?
--
Go to Diagnostic Trouble Code (DTC) List
System OK
Was this
answer
helpful?
Yes
No
Wednesday, February 17th, 2010 AT 11:24 PM

Please login or register to post a reply.

Recommended Guides