Sometimes when i start my blazer the check engine light comes on as im just idling, every so often comes on while sticking to an avg speed of about 45-50, but when i give it a little gas to take off from sitting still or to pass someone it goes off. Truck never runs rough or anything but the light comes on and goes off. any suggestions what the culprit could be?

ive got a 92 S10 Blazer CPI

 

my 1990 fullsize would do this everytime i held a speed on the highway then would go off. it was the egr valve. you can probably still scan it and find out what it is even though its not showing

 

i was told maybe the EGR or an O2 sensor but figured id get a second or multiple opinions from the forum. thanks man

 

yeah just get it scanned if you can find someone who has the old obd1 scanner. ive scanned my 90 and 93 with no light on and it still told me all the codes it was throwing. i drove my truck like a year like that before i finally fixed it. figured it ran fine i dont want to mess with it

 

your ecu has stored the code, you can either get an odb1 scanner to retrieve the code, watch how many times it blinks and from there you can figure it what the code means. Hope that helps