1989 corvette convert idle

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Sep 29, 2009 | 05:53 PM

vanderb

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Intermediate

Joined: Sep 2006

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From: London

1989 corvette convert idle

When I start the car the idle varies between 600 and 800 rpm for the first 3-4 minutes. the service engine light is on and will not go our. Any ideas as to what sensors I should be checking??? Any help appreciated.

Sep 29, 2009 | 05:58 PM

BADDUCK

Le Mans Master

Joined: Jun 2006

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From: One day you're a Comet...the next day you're dust... Arkansas

Check/clean the IAC.

Sep 29, 2009 | 06:59 PM

0Paul Ruggeri

Former Vendor

Joined: Nov 2006

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From: Carmichael ca

Check to see what code is causing the light to come on.

Sep 30, 2009 | 02:22 PM

josephf31

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Joined: Mar 2008

Posts: 579

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From: High Bridge New Jersey

Check

Quote:

Originally Posted by vanderb

or replace the O2 sensor...

Sep 30, 2009 | 08:04 PM

avgjoe

Instructor

Joined: Nov 2008

Posts: 169

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From: Harrisonburg VA

I would guess the O2 sensor also, but that is just a guess without a code.

Oct 1, 2009 | 10:46 AM

vanderb

Thread Starter

Intermediate

Joined: Sep 2006

Posts: 41

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From: London

Aic

I don't have a code reader buts sounds like getting one would be useful. My mechanic sprayed the AIC and it seems to have improved it abit but I still get alittle variation in idle speed. He also tried to reset the Service Engine Soon light but it came back on almost immediately. Can this variation cause the SES light to come on or is this caused by something else?? I'll try to find someone with a code reader and get the code(s). Other than that is runs great. Any other ideas as to what to check would be appriciated and thanks for your help.

Oct 1, 2009 | 05:19 PM

IslandPirate

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Joined: Sep 2009

Posts: 69

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From: Houston TX

You can read it without a code reader.
Grounding A and B on the diagnostic connector under the steering wheel will cause the SES light to flash the stored codes.
(and grounding A and K will flash the SIR light if it is showing faults.)

Oct 1, 2009 | 06:57 PM

floridamale

Safety Car

Joined: Jan 2008

Posts: 3,939

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From: Vero Beach Florida

This link tells you how to check
http://www.corvettebuyers.com/c4vettes/codes.htm
There are the codes
1985-1991: ECM Codes
Code #12: Normal No Codes.
Code #13: Open Oxygen Sensor Circuit.
Code #14: Coolant Sensor Circuit Low.
Code #15: Coolant Sensor Circuit High.
Code #21: Throttle Position Sensor High.
Code #22: Throttle Position Sensor Low.
Code #23: Manifold Air Temperature Circuit High.
Code #24: Vehicle Speed Sensor.
Code #25: Manifold Air Temperature Circuit Low.
Code #32: EGR System Failure.
Code #33: Mass Air Flow Sensor High.
Code #34: Mass Air Flow Sensor Low.
Code #36: Mass Air Flow Sensor Burn-Off Function Fault.
Code #41: Cylinder Select Error.
Code #42: Electronic Spark Timing.
Code #43: Electronic Spark Control.
Code #44: Lean Exhaust indication.
Code #45: Rich Exhaust Indication.
Code #46: Vehicle Anti Theft Fault.
Code #51: Faulty Mem-Cal.
Code #52: Fuel Calpak Missing.
Code #52: (1990-91 Corvette Only): Engine Oil Temperature Sensor Low.
Code #53: System Over Voltage.
Code #54: Fuel Pump Circuit Low Voltage.
Code #55: Defective ECM.
Code #62: Engine Oil Temperature Sensor Circuit High.