Vibration at idle in gear

Hi,

The idle speed is too low I tried finding information related to the IAC, and came across a flow chart regarding it and how to check. Idle speed should be around 700 in neutral. So 600 to 650 in gear would be normal.

According to the manual, the idle speed should not be tampered with because it can throw off other things. Take a look through this flow chart. See if it helps narrow down the idle speed issue. The attached pics correlate with the directions.

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1999 Saturn SL2 L4-1.9L DOHC VIN 7
Minimum Idle Speed Adjustment
Vehicle Powertrain Management Fuel Delivery and Air Induction Idle Speed Adjustments Minimum Idle Speed Adjustment
MINIMUM IDLE SPEED ADJUSTMENT
Minimum Air Idle Speed Specifications

Pic 1

MINIMUM IDLE SPEED ADJUSTMENT

WARNING: The vehicle wheels must be blocked and parking brake applied when checking idle speed.

NOTE: Minimum Idle Speed adjustments are set at the factory and MUST NOT be tampered with to alter minimum or maximum engine idle speed. Improper adjustment of the idle speed screw can cause false PCM codes, idle instability and automatic transaxle shift concerns, etc.

NOTE: On original equipment throttle bodies, a tamper resistant screw is used to regulate minimum idle speed of the engine. Adjustment of this screw is not to be performed.

1. Block wheels and apply parking brake.

Figure 1 - Hookup Of IAC Tester. (Typical)

Pic 2

2. Connect the IAC tester (Saturn Tool) SA9195E, or the Scan tool unit. The IAC pintle must be seated in the throttle body.

NOTE: A/C, cooling fans and electrical loads must be off when checking idle speed.

IAC air plug installed for Minimum air adjustment

Pic 3

3. Insert the IAC air plug in the throttle body.
(Saturn Tool) SA9106E used for SOHC (L24)/DOHC (LLO)

4. Using Scan tool unit, check idle speed. If not within specifications (0 rpm [stall] to 700 rpm):
Inspect throttle blade for binding. Clean bore if necessary. Replace throttle body if throttle blade continues to bind after cleaning.
Inspect for vacuum leaks at vacuum hoses and gasket surfaces. Correct any vacuum leaks.

NOTE: Engine must be at normal operating temperature (upper radiator hose warm). Spark adaptive cells must be at "0."

5. If the minimum idle speed is above 700 rpm after performing the required repairs, replace the throttle body. Do not adjust minimum idle.

Pic 4

6. Using Scan tool unit, check voltage on TP sensor. Do not replace the sensor unless setting is outside of 0.35-0.70 volt limit.
7. Remove IAC air plug.
8. Start engine and check for proper idle operation.
9. Refer to Fuel System or Computer System diagnostic charts if concern is not corrected.

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Let me know if this helps or if you have other questions.

Take care,
Joe

You are very welcome, Dave. If you have a chance, let me know what you find or if you need help with anything.

Take care,
Joe