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1997 ford taurus revs when idling
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richs224
New User
Jan 10, 2009, 2:03 PM
Post #1 of 4
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1997 ford taurus revs when idling
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I have a 1997 ford taurus with 155,000 miles on it. a couple of months ago i noticed that the when idling or when braked, like at a red light, the engine would slightly rev and the car would jump forward a bit. in the time since then it has gotten just a bit worse and it now revs every few seconds causing the car to jump and shake. i have not really done anything to fix the problem besides getting an oil change and putting some fuel injector cleaner in the gas tank.
Thanks in advance for any advice
richs224
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way2old
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/ Moderator
Jan 10, 2009, 3:15 PM
Post #2 of 4
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Re: 1997 ford taurus revs when idling
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When this happens, is the defroster or A/C on? If so, look at the Idle Speed Motor. If the compressor is on and engging, it could cause the rpm's to fluctuate when the compressor engages. Notice the next time it happens and if defroster or A/C is on, turn it off to see if it helps any.
Being way2old is why I need help from younger minds
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zmame
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/ Moderator
Jan 24, 2009, 10:42 PM
Post #3 of 4
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Re: 1997 ford taurus revs when idling
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Found TSB on inford.com
TSB 02-22-1 FORD: 1994-1997 COUGAR, THUNDERBIRD
1995-2003 SABLE, TAURUS
1996-2003 MUSTANG
1995-1997 AEROSTAR
1995-2003 RANGER, WINDSTAR
1996-2000 EXPLORER
1997-2000 MOUNTAINEER
1997-2003 E SERIES, F-150
ISSUE:
Incorrectly installed gear driven camshaft position (CMP) sensor synchronizer assemblies may be hard to diagnose. Vehicle may exhibit poor fuel economy, driveability Diagnostic Trouble Codes (DTCs) P1336, P1309, P0340 with MIL light on. Loss of power, surge, hesitation and runs rough on acceleration may also be present. ACTION:
New diagnostics have been developed for WDS to diagnose incorrectly installed gear driven camshaft position (CMP) synchronizer assemblies. Refer to the following Service Procedure to diagnose a possible mis-installed synchronizer assembly and proper installation procedure. SERVICE INFORMATION
Items Covered In This Article:
- "Hall" vs. "VRS" sensor function
- Vehicle history scrutiny for past service of the synchronizer assembly
- WDS - Power balance test
- WDS - CMP and CKP wave signal comparison
- Wave Comparison chart - CMP vs. CKP
- Correct (CMP) synchronizer installation tool application & installation procedure
- "Top Dead Center" (TDC) alignment
- Synchronizer installation tool application chart
Hall - Effect (Hall) and Variable Reluctance (VRS) CMP Sensors
CMP sensors are used on all current model year engines, regardless of fuel system or ignition system type. The CMP sensor provides the Powertrain Control Module (PCM) with cam position information to indicate # 1 cylinder, on the compression stroke
There are two different types of CMP sensors: - The three- pin, Hall-effect sensor (Figure 1)
- The two-pin Variable Reluctance sensor (Figure 1)
Although the Hall-effect (three-pin) and the Variable Reluctance (two-pin) CMP sensors perform the same function, their signal appearance is quite different and they are not interchangeable. - The three-pin Hall-effect sensor uses a Hall effect device and a magnet to generate a digital square wave signal (Figure 2)
- The two-pin Variable Reluctance sensor is a magnetic transducer, which uses differential voltage across windings to generate a voltage waveform that is similar to a sine wave (Figure 2)
Both sensors provide a switching voltage as the engine rotates. SERVICE PROCEDURE
If you suspect that a vehicle (engine) may have had the synchronizer assembly (Figure 3) installed incorrectly, check the vehicle history to see if related service has been performed. If you determine that the synchronizer could have been installed incorrectly, use the following procedure with WDS to verify correct installation (Figure 5).
NOTE: CORRECT CAMSHAFT POSITION SYNCHRONIZER ASSEMBLY INSTALLATION IS CRITICAL. AN INCORRECTLY INSTALLED SYNCHRONIZER CAN CAUSE HARD TO DIAGNOSE DRIVEABILITY CONDITIONS AND POSSIBLE SERIOUS ENGINE DAMAGE.
Reasons for incorrect installation are: - Not setting the # 1 cylinder on Top Dead Center (TDC) of the compression stroke
- Use of the incorrect camshaft synchronizer tool for installation
- Incorrect alignment of the synchronizer tool
Power Balance Test In WDS
The WDS Power Balance Test can be used to quickly determine if the CMP synchronizer assembly is installed incorrectly. Use the following procedure. - Run the vehicle while viewing the power balance test in WDS to insure that no engine misses are occurring.
- Shut the engine off and remove the # 1 cylinder injector electrical connector.
- Start the engine and view the WDS power balance test.
- The test should indicate a power loss in the # 1 cylinder (Figure 4).
- If the # 1 cylinder is indicated, then the CMP synchronizer assembly IS NOT grossly mis-installed. (Figure 4) Continue to Step 5 in this procedure
- If any other cylinder is indicated during the power balance test, then the CMP synchronizer assembly HAS BEEN INSTALLED INCORRECTLY, and must be reinstalled. (Refer to the installation procedure, tool chart and TDC reference described in this TSB, or refer to the appropriate model year Workshop Manual Section 303-14, Synchronizer-Camshaft).
- If power loss is indicated in the # 1 cylinder (Figure 4), connect a 104 pin break-out box between the PCM and the PCM electrical connector.
- Insert the red WDS probe into pin # 21 and the black WDS probe into pin # 85 of the break-out Box.
- Select oscilloscope from the WDS Toolbox.
- Select "Channel one Auto Mode", then select the Crankshaft Position (CKP) sensor.
- Select "Channel two Auto Mode", then select the CMP sensor based on whether it is a VRS (2-pin) or Hall-effect (3 pin) CMP sensor.
- Press the start button and view both the CKP sensor as well as the CMP sensor signals. Figure 6, 7 and 8).
- Compare the wave forms of both sensors.
- The missing tooth of the CKP sensor trigger wheel will be shown on the screen as an extra space between the wave forms. This position is 60° Before Top Dead Center (BTDC)
- The upper peaks of the wave form are each spaced 10° of crankshaft rotation apart
- The CMP timing setting on all current 6-cylinder engines should be between 10 and 40° After Top Dead Center (ATDC)
On all Hall-effect sensors, the CMP wave form rising edge should occur between the 7th and the 10th peak past the missing tooth. (Figure 6)
On the VRS sensors (except 5.0L engines), the falling edge of the CMP waveform should cross the zero reference line between the 7th and 10th peak past the missing tooth waveform. (Figure 7).
On 5.0L engines with a VRS CMP sensor, the falling edge waveform should cross the zero reference line between the 6th and the 9th peak past the CKP missing tooth (Figure 8).
On 5.0L engines with a Hall-effect VRS CMP sensor, the rising edge of the wave form should occur between the 6th and 9th peak past the CKP missing tooth wave form.
(CMP) SYNCHRONIZER INSTALLATION PROCEDURE
- Set the # 1 cylinder on Top Dead Center (TDC) of the compression stroke.
NOTE: THE # 1 CYLINDER MUST BE SET ON TOP DEAD CENTER (TDC) OF THE COMPRESSION STROKE OR THE SYNCHRONIZER ASSEMBLY WILL NOT BE INSTALLED CORRECTLY.
- Disconnect the battery ground cable.
- Remove the CMP sensor from the synchronizer assembly.
- Remove the synchronizer clamp (hold down bolt) and remove the synchronizer assembly.
NOTE: IN SOME CASES THE OIL PUMP INTERMEDIATE SHAFT MAY NOT COME OUT WITH THE SYNCHRONIZER ASSEMBLY. IF SO, RETRIEVE THE INTERMEDIATE SHAFT BEFORE PROCEEDING.
- After performing the required service and before beginning the installation of the synchronizer assembly, ALWAYS COAT THE SYNCHRONIZER DRIVE GEAR WITH CLEAN ENGINE OIL PRIOR TO INSTALLATION.
- Install the correct engine and model year synchronizer alignment installation tool. Install the tool to the synchronizer assembly by rotating the tool until it engages the notches in the camshaft synchronizer housing and the armature (Figure 10).
 CAUTION: SOME OF THE TOOLS WILL FIT ACROSS ENGINE LINES AND COULD BE PERCEIVED AS BEING THE CORRECT TOOL. ALTHOUGH THE TOOLS MAY APPEAR SIMILAR, THERE ARE SUBTLE DIFFERENCES BETWEEN THEM, ALWAYS CHECK THE TOOL APPLICATION CHART PROVIDED IN THIS TSB (FIGURE 9).
- During the installation of the synchronizer assembly (with the tool attached) into the engine, the arrow on the tool will rotate until the intermediate shaft and the camshaft gear fully engage.
NOTE: THE ARROW WILL ROTATE CLOCKWISE OR COUNTER CLOCKWISE DEPENDING ON THE ENGINE TYPE AND ENGINE ROTATION.
- Install the camshaft synchronizer assembly so the arrow on the installation tool (Figure 3) is in the correct position as specified in the appropriate model year vehicle and engine. (Refer to Workshop Manual Section 303-14, Synchronizer-Camshaft).
- Install the synchronizer clamp (bolt) before removing the installation tool. Tighten to 18 Lb-ft (25 N-m).
- Remove the installation tool.
- Install the CMP sensor. Tighten to 27 Lb-in (3 N-m).
- Install battery ground cable.
CAUTION: DO NOT LOOSEN THE SYNCHRONIZER BOLT AND ROTATE THE SYNCHRONIZER ASSEMBLY. THE SYNCHRONIZER ASSEMBLY IS NOT ADJUSTABLE; DO NOT LOOSEN THE SYNCHRONIZER BOLT AFTER THE ALIGNMENT TOOL HAS BEEN REMOVED IN ORDER TO ALIGN THE CMP ELECTRICAL CONNECTOR FOR ANY REASON. IF THE ELECTRICAL CONNECTOR IS NOT IN THE CORRECT POSITION, THE SYNCHRONIZER ASSEMBLY HAS TO BE REMOVED, THE ALIGNMENT TOOL REINSTALLED AND THE ASSEMBLY REINSTALLED ASSUMING THE ENGINE HAS NOT BEEN ROTATED FROM TDC OF THE COMPRESSION STROKE ON # 1 CYLINDER.
(This post was edited by zmame on Jan 24, 2009, 10:54 PM)
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Jeff Norfolk
Enthusiast
Jan 25, 2009, 12:29 PM
Post #4 of 4
(7192 views)
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Re: 1997 ford taurus revs when idling
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To add if the engine is surging it is searching for idle speed. Usually a vacuum leak(typically an idle air control valve as Way2old mentioned). Common failure on Fords around this year model. Since you mentioned it happens when you are breaking you may check the vacuum brake booster for leaks. Any vacuum system leak will cause this symptom.
Jeff
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