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engine light on 81 vette

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Old Nov 3, 2011 | 09:49 PM
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Default engine light on 81 vette

i have a problem on my 81 vette i just install side pipes and hooker header on it and now my engine light went on and it stay on i dont know what to do can any 1 out there help me? thanks alots
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Old Nov 3, 2011 | 09:52 PM
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remove the ecm
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Old Nov 3, 2011 | 09:58 PM
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what is ecm?
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Old Nov 3, 2011 | 10:46 PM
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Did you keep the O2 sensor on the car?
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Old Nov 4, 2011 | 12:02 AM
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The '81 car had the first version of electronic controls for the engine. It had a unique (one year only design) carburetor, distributor, and ECM (electronic control module...computer). It also had an oxygen sensor in the exhaust downpipe which sent emission data to the ECM for regulating fuel mixture and distributor timing.

If your "Check Engine" light is on, there is a trouble code that has been logged into the ECM. You need to download that code and address the respective hardware problem indicated by the code(s).
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Old Nov 4, 2011 | 10:08 AM
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Originally Posted by forvicjr
remove the ecm
Avitar says it all.


Listen to 7T1.
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Old Nov 4, 2011 | 11:58 AM
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7T1 and A1 are correct.
You may not have installed the O2 sensor back in the drivers side header.
No reason at all you can't make significant HP gains With the CCC in place and functioning
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Old Nov 4, 2011 | 12:20 PM
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Originally Posted by larryg3
Did you keep the O2 sensor on the car?
Bingo.
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Old Nov 4, 2011 | 01:04 PM
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Yes my first thought 02 sensor.
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Old Nov 4, 2011 | 01:17 PM
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The computer will tell you why -- read the codes. To do this, pull the ash tray, there is a connector directly under it. With engine off, short the two pins closest to the driver side. turn on the key (not the engine) the check engine light will begin to blink (you will also hear an audible clicking in the engine compartment, it is the carb mixture solenoid switch and is normal). One blink, pause, two blinks (code12) and repeat that three times. After the code 12 (normal, happens every time) there will be one or more codes blinked at you (example: Blink, Blink pause, blink, blink, blink is code 23). It will blink each code three times. When all codes are complete there will be another set of three 12's. When you see the 12 again you are done.
Let us know what the codes are and we can help you from there. Also, think about getting an 81 service manual, fantastic section on the CCC

My first thought -- did you connect the oxygen sensor back up, should be on the downtubes of the drivers side header

Last edited by wajulia; Nov 4, 2011 at 01:21 PM.
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Old Nov 4, 2011 | 01:24 PM
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Since he just installed headers and sidepipes it pretty obvious it is a missing 02 sensor, in which case you have 2 options:

1) weld a bung into your sidepipe or header and re-install the sensor, or
2) Remove the ECM, which means you'll also have to replace the carb and distributor.
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Old Nov 4, 2011 | 02:01 PM
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How about a picture. I don't think I've seen a late C3 with side pipes.
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Old Nov 4, 2011 | 02:05 PM
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^ x2
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Old Nov 4, 2011 | 04:30 PM
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I do not mean to hijack the thread but here is a pic of my '81 vette. I put on the hooker headers and side pipe this year.


Last edited by larryg3; Nov 4, 2011 at 04:34 PM.
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Old Nov 4, 2011 | 04:33 PM
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sweet!
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Old Nov 5, 2011 | 11:30 AM
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Yup a1 thats my car in its present state, and it still probably looks better than yours.
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