Revving up engine

CHRISTINE NELSON

MEMBER
2000 SATURN SL2
2WD
AUTOMATIC
150,000 MILES

Engine at times when first starting revs up and while running will quit. I wait a few seconds and start it and then it seems fine. Once it quit with blue smoke. It just started doing this revving up in the past month. Once it took 3 times before it started, but ran fine to get home. Mechanic can't seem to find the problem as he can't seem to get it to do it for him. I am afraid to take it on the road.

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,645 POSTS

Welcome to 2CarPros.

Often times an erratic idle is caused by either an idle air control valve or an engine vacuum leak. Take a look through this link. It explains how to find a vacuum leak.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Also, here is a link that shows how to replace an idle air control valve if you find it is bad. Remove it first and check for dirt or carbon where it enters the throttle body. Also, make sure the pintle is not damaged or dirty. The pics correlate with the directions.

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IDLE AIR CONTROL (IAC) VALVE

REMOVAL

Idle Air Control Service
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1. Ignition Off.
2. Remove air induction tubing from throttle body to air cleaner.
3. Disconnect IAC valve harness connector.
4. Disconnect TP sensor harness connector.
5. Disconnect MAP sensor harness connector.
6. Remove IAC valve attachment screws and IAC valve.

NOTE: The IAC valve is an electrical component and must not be soaked in any liquid solvent; otherwise damage could result.

7. Remove O-ring from IAC valve and discard.

INSTALLATION

Idle Air Control Service

pic 1

1. Clean IAC valve seating surfaces on the throttle body to assure proper seal of the new O-ring and contact of the IAC valve flange.

IMPORTANT:
Before installing a new IAC valve, retract the pintle using the Scan tool. Refer to Scan tool user guide.
Normal wear of the IAC pintle, characterized by a ring around the cone, is not an indication of a bad IAC valve.

2. Lubricate new O-ring with clean engine oil and install on IAC valve.

NOTE: If replacement is necessary, be sure to replace with an identical part. IAC valve pintle shape and diameter are designed for specific applications.

Idle Air Control Valve.

Pic 2

3. Insert IAC valve in throttle body.
4. Install IAC valve attachment screws using thread coating, Saturn P/N 21485277 (Loctite 242(R) Threadlocker or equivalent).

Torque:
Idle Air Control Valve: 3 N.m (27 in-lbs)

5. Connect IAC valve harness connector. Push in connector until a click is heard and pull back to confirm a positive engagement.
6. Connect MAP sensor harness connector. Push in connector until a click is heard and pull back to confirm a positive engagement.
7. Connect TP sensor harness connector. Push in connector until a click is heard and pull back to confirm a positive engagement.
8. Install air induction tubing from throttle body to air cleaner.

IMPORTANT: The PCM will have to go through an IAC relearn process once the new valve is installed. The vehicle should be run at normal operating temperature while varying the engine RPM slowly between 3500 rpm and idle two or three times.

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

Take care,

Joe

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