Goodmorning everyone...hope you all are enjoying the holidays... I have a quick tech question for you...
I am new to the 'vette world and am curious about retrieving codes. I have a 91 Coupe L98 and am experiencing a slight miss. Is there a way to see if the on board computer has stored any codes that might lead me down the right path to repair? Your anticipated help on this one is appreciated. Have a Happy New Year everyone!!!!!!!

 

I dont know if your year applies to your year but you bend a paperclip in a u shape and put one in the first and last outlet**I dont know what those are called**. Turn the ignion key to on but dont start it. It will flash code 12 3 times then will show you the codes then flash code 12 three more times and that signals its done. NOW, I cant get all the technical details but thats what it is like on my car. I dotn know what you call the slots though on the top. I just put it in the first and last hole.

 

that description/advice is priceless! just don't follow it!
http://www.troublecodes.net/GM/

You will be shorting together A & B (you have the 12 pin DLC type connector), not "the first and last outlet" ......

 

I dont know if your year applies to your year but you bend a paperclip in a u shape and put one in the first and last outlet**I dont know what those are called**. Turn the ignion key to on but dont start it. It will flash code 12 3 times then will show you the codes then flash code 12 three more times and that signals its done. NOW, I cant get all the technical details but thats what it is like on my car. I dotn know what you call the slots though on the top. I just put it in the first and last hole.
__________________
Love hurts. Girls cheat. I whip @$$.........I love ashley.


Yikes!!!!!!!! When my head stops spinning, I'll get out my Captain Crunch Decoder Ring and try and figure out what you're telling me to do. Thanks...

 

http://members.shaw.ca/corvette86/No...it%20Check.pdf

 

I remember reading something similar when I had to do it to my car......I never could read the codes though. I thought I was doing it right. The light blinked alot.

 

If you don't know the answer to someones question, simply do not respond. With that said, don't go posting nonsense like you did in this thread... "The light blinked alot"......that's informative...maybe you should go over to C4 general section, not as technical, and you are more apt to get away with the silly postings.

 

Mike: The paperclip will work fine. However, you can go to Auto Zone and get a FREE key to use in place of the bent paperclip. Here is a picture of the key for your reference:



As stated in earlier posts, place the two ends of the key in the A & B positions in the ALDL connecter (under steering wheel on RHS). Turn on the ignition and do not start the engine. Watch and count the flashes of the service engine soon light. It is normal to get 1, 2, 1, 2, 1, 2 and then any stored codes will flash. Please note there may be more than one code stored. After all codes have been flashed, you will get the 1, 2, 1, 2, 1, 2.

Do this and let us know what you find. We are here to help each other

Happy New Year.

 

Thanks Sam Lam, that makes a little more sense than the previous reply. Thanks for taking the time to spell it out for me...

 

Ok - now that you know how to do it - an active trouble code will turn on the Check Engine Light and keep it on until the problem is fixed - or the problem goes away. If it's not illuminated, there isn't a problem (or if there is, your Check Engine Light is burnt out or it's circuitry is bad). You might retrieve codes that are stored as History (usually for no more that 100 key cycles), but it will probably have nothing to do with your miss. I'd verify that the Check Engine Light comes on when you first start it (that's a built in bulb check), and if it immediately goes out, look for something else being the cause of the problem. If you would like to try to isolate the miss to a single cylinder, get some 1/4 inch vacuum hose and cut it into 8, one inch pieces. Insert a piece between each plug wire and the distributor cap and then start it. Then, with a grounded test light, touch each piece of vacuum hose to kill a cylinder will observing a tach. Note the RPM drop. Any that don't drop the same as the other is where you should start looking for the miss.

 

OK, sounds like a plan...let me ask one more question, will a vaccuum leak cause a miss?

 

Hard to say - a vacuum leak can cause the Oxygen Sensor to report a lean condition to the ECM. The ECM then adds too much fuel causing it to run rich. If a plug or plugs foul, that can lead to a miss. To determine if it's rich (or lean), you need to hook up a scanner. If you don't have one, I'd try to isolate the condition to a single cylinder first.