98 sonoma idling problem

[steve2005]

I just bought a 98 sonoma 5 speed 4.3L, I drove it for two days then all at once I the engine started taching up frequently, I called the dealer and they told me this was normal to keep the truck from shutting off. I know it is normal for it to do this once in a while but it does it about every 5 seconds or so now. It jumps from 500 rpms to 1000 then it goes right back down. It does this even when it is in gear. Someone please help I have no idea where to start. Thanks. (this strarted soon after I fueled up for the first time, I used regular and I don't know what was used before)

[steve2005]

Ok, my truck isn't having the same problem today. It must have been when it was warm or something since I had been driving for a long time when it started happening. I have only had the truck for about 3 days now, does anyone know what it could have been.

[steve2005]

I just thought I'd let you know what the problem was with my truck. I brought it to the GM dealer and they scanned it and found out cylinder #2 wasn't firing. They took out the spark plug and saw that it had been bent and the porcelain was broken. They said something must have come in through the air intake and hit the plug. They put in a $2 plug and a ten minute job that I could have done myself turned into over $100. Oh well my truck runs good now and I have a lot more power.

[johnsbackintown]

Originally Posted by steve2005

I just thought I'd let you know what the problem was with my truck. I brought it to the GM dealer and they scanned it and found out cylinder #2 wasn't firing. They took out the spark plug and saw that it had been bent and the porcelain was broken. They said something must have come in through the air intake and hit the plug. They put in a $2 plug and a ten minute job that I could have done myself turned into over $100. Oh well my truck runs good now and I have a lot more power.

If you believe that then I got some ocean front property in Kansas I would like to sell you! That is unbelieveable!

[dtl379]

Sound like a misfire, and they don't always send codes. Aparently any engine noise or jumping is normal to GM. Normal my A*#!! Look into running injector cleaner like chevron with techron or prestone's 0-60 through the system, check your injectors, spyder lines, EGR valve(check for carbon), TPS, ignition coil, wires, throttle body (check for carbon), and possibly the camshaft position sensor or crankcase sensor. If all else fails, move to California where they got a recall, and have the truck serviced there, if that doesn't conflict too much with your daily schedual, that is.