ok here is what is going on. Two days ago i was driving and it stated making a popping noise every now and then and when it maid the popping sound it would jolt or hesitate for a second. Now as of yester day when i first start it it will idle at about 1500 until i put it in drive and then i goes aroun 750 or 800. And then after i have been driving for a while it likes to dip under 500 and sometimes stall at the stop lights. Do you know what it might be? I know it could be a ton of things. It just clicked the check engine light on but i havent had a chance to check the codes yet. The engine i have is an 305 LG4 with a computer controlled Q-jet.

 

check for codes, fix any problems related to the ecm controls and make sure the tune up is good then repost

 

potential O2 sensor problem. When's the last time you've replaced that?

 

Yeah im going to check the codes tonight. I cant do it right now because im babysitting my neices this week. So i will check them fix them and repost but does anyone have a suggestion that itmight be? It has probably been 2 or three years since i replaced the o2 sensor.

 

I'm in the same boat.

Yes, my 1998' O2 sensor is bad. I'm replacing the O2 this weekend and reposting the new condition the next monday.


Denis V.

 

I am having the same exact problem in my 92 RS 305. To the tee. I have not had the time to do a tune up or run codes but I hope it solves the problem it is driving me nuts(embarassing) car sits sweet rumbleing then stall --------------Let me know if you solve it before me!!!!

 

Well i tried to diagnos it but i cant get it to go in diagnostic mode. I jumper slot a and b which are the 2 top right pins with the ignition on and i get nothing. No code 12 still just a solid check engine light. Got any suggestions now?

 

I'm guessing that when you jumped slots A to B, that you already had the key to the "ON" position?
If that is the case, turn ign off, then back to "on".

 

Another good place to check would be the PCV and its hose. Take the PCV out and shake it to see if it rattles, if it doesn't, replace it and remove the hose and spray some carb cleaner through it. Also check the hose for cracks and holes since it is a vacuum source.

 

I replaced O2, ignition module and EGR valve (all news) and the problem remains the same.

I bought new injectors on ebay, because I think the injectors are bad. My theory is: when injectors are hot, resistance/impedance is very different, then they don't works at the right flow and engine RPMs are low.

 

Some earlier model GM's had the diagnostic pins A and B set as the top right and lower right pins. Just a suggestion, not sure exactly what years they cover.