Hi first time posting on here. I just bought this 1983 firebird the other day with a 305 v8 in it. Runs and drives amazing. However when im at a red light idling the check engine light comes on and stays there till i accelerate then goes away. She idles perfectly nothings shaking and i checked for vacuum leaks and found nothing. Just cant diagnose the problem as to why the engine light comes on and off light that. someone help please!

 

You need to check and see what code it's sending.

 

How can i check what code it's sending when the check engine light won't stay on long enough for me to do that?

 

It stores the info.

 

there's a ECM terminal just right under the steering wheel.jump A&B Terminal and it will start a diagnosis of the codes your receiving

 

Okay I need to go to a store and get it checked out cause I do not own the proper thing to check the codes. But does anyone have a general idea what it could be?

 

A paper clip can be used to jump the terminals, SES/CEL will blink out the codes. Jump the terminals first, then do a key-on, engine-off to blink the codes.

Do not start or crank the engine with A & B jumped on a carb'd car.

RBob.

 

And how would
I know what the codes mean exactly. I do not have a manual for the car

 

first when you jump the A,B terminals,your going to here the fans come on.The coding will start with 12 three times it will sound like this,ding---dingding, ding--dingding,ding--dingding that means the single ding is one(1) and the second dingding is 2, that means the code is Twelve(12) you will here the 12 3 times ,that means the ECM is starting a diagnostics of the car,then you will start receiving additional codes, example if you here dingdingding (short pause) dingdingding,that's code 33,you will here each code 3 times etc,etc,etc The diagnostics will be finished when you here ding--dingding that's 12 the test is over.After you get all your codes or code,come back here and list them,you will get plenty of help.

 

DO a search here on the boards, there are a few posts with a complete code list. 12 is the standard "I'm here, OBD circuit is functional" code. Means nothing is wrong.

Based on what you have said about it, I would suspect three things.

1. O2 sensor is shot.
2. NEed a new cat
3. Carb needs tuned.

It's most likely a rich/lean indication. I had an issue like it when I swapped in a 350 and wasn't tuned properly, the motor was running rich/lean at weird times. Went away mostly when I got it tuned. Only happens now when I let it idle for 10+ minutes. I call it a "soft" code because it's not stored passed starting the car. Meaning if the code comes on, to get the reading, you need to shut the car off, turn it to run and pull the code. The moment you start the car, the code is dumped from memory.

 

my friend that went to uti said if it is flashing, it is bad and do not drive it till you figure it out

 

I wouldn't go as far as to not driving it!!it's probably something just miner,But I would have it looked at ASAP.

 

Okay so I got it looked at and they said the codes 13 21 and 45 appeared. And that it is either the O2 sensor or the throttle position sensor. But most likely the O2 sensor. So ima replace that and see what happens its
Only 60 bucks