Need advice please

[Customcar]

My 1986 vette has had the exaust system replaced.

Problem Service engine light comes on once in every three start ups and stays on till you stop driving.

Had computer check it out and it nothing shows as a problem.
Told me it would probably go away after muffilers break in as the new mufflers seemed to be the problem.
Car runs great
Ken[

 

[Edmond]

The service engine light has to do with something triggered by a computer related problem, most likely a faulty sensor.

The new mufflers will have nothing to do that light coming on.

Where did you get it scanned at?

 

[Customcar]

Thanks for the reply Edmond
When I purchased the car a couple off weeks ago the fellow said he had taken it in (I am not sure where) and this is what they told him .
I am waiting for my neighbor machanic to bring home a computer checker from work to retest the car .
If nothing shows up would you replace the sensor???
Ken

 

[Edmond]

Thanks for the reply Edmond
When I purchased the car a couple off weeks ago the fellow said he had taken it in (I am not sure where) and this is what they told him .
I am waiting for my neighbor machanic to bring home a computer checker from work to retest the car .
If nothing shows up would you replace the sensor???
Ken

Ken,

You can actually check the codes yourself without a scanner. You just jump two ports. I can't remember which ports they are off the top of my head. They're either the lower two left or lower two right ports that are right next to each other. You can use a paper clip to jump them. When you have them jumped, turn the key but don't start the car. You will get a series of flashes of the service engine light. Count the flashes and let us know what the numbers are.

There are many sensors that could trigger that SES light. But I think a common culprit is the O2 sensor, which is an easy fix for $30. I'm not saying that's what it is but it's a possibility.

I think we should have your problem solved by tonight!

 

[MBDiagMan]

Use a paper clip to short pins A and B on the ALDL connector above the drivers right knee. Do this with the ignition off, then turn on the engine. It will flash once, pause then flash twice. This is a twelve. It will flash the 12 two or three times, then if a code is stored, and I expect that there is, it will flash the code. An example might be three flashes, a pause and then four flashes. That would be a code 34. It will blink that code two or three times, then blink another if there are more, then it will finish up by blinking a 12 a few times to let you know that it is finished.

BTW, it is the Service Engine Soon light that will be doing this blinking.

Once you get the code or codes, post them here and we can tell you what subsystem is being effected. My bet is on the Oxygen sensor sense it was disturbed for exhaust work.

Good luck,

 

[Customcar]

where is knock sensor located???

computer shows knock sensor .
Where is it located.
Thanks Ken