Surging, Bucking, Backfire

Ok, here is my situation. I noticed a week ago that in single digit outside temperatures I would get a slight, once in a while "miss or buck" in the engine under a slight load. Twice going up a grade I heard the engine pop back through the throttle body. Did not do it again until I changed the Mass Airflow Sensor with a GM Rebuilt, straight from GM(the screen was badly damaged when I bought the car two months ago). In the process of replacing the MAFS, I cleaned the Throttle Body plate -which had been sticking and also cleaned the Idle Air Control which was carboned up pretty good as well (Used the Throttle Body cleaner spray -GM safe). Replaced the MAFS and started it up and it idled and ran just fine.

Today with temps in the low teens there was a good bit of surging at rpm's around 2500 and up and below 2000 it would buck like some cylinders were misfiring. I would also say the surging felt like cylinders misfiring. The problem seems to be worse now at night with the temps around 0.

Now, in replacing the MAFS, have I made the system more sensitive with the proper screen? Or, is this just plugs/wires getting worse?

Surely would appreciate your help on this one. THANK YOU.

I had a similar situation. Plugs and wires.

Does it smooth out when the engine is warmed up or no?

Had simlar problems but I love in FL so no cold weather. Was the coil stack for me.

No change when engine is warmed up. I have suspected the coil pack too. But, how do you differentiate between it and the plugs/wires except by replacing?

Thanks for the input Gentlemen! Plugs and wires at 76,500 took care of the rough running/missing for my 98 Aurora. I really suspect that the wires were the main problem and not the plugs. However, I was there and felt it best to go ahead and take care of it all at once.

Thanks for the input Gentlemen! Plugs and wires at 76,500 took care of the rough running/missing for my 98 Aurora. I really suspect that the wires were the main problem and not the plugs. However, I was there and felt it best to go ahead and take care of it all at once.


Good to hear your problem was fixed. I hope you used AC Delco plugs and wires or you may be having this problem agian very shortly.

I got my plugs and my plug wires replaced and it really helped, unfortunately the car still backfires occasionally, but just when you're starting it. It's weird, because it doesn't produce exactly the sound I would expect when it does it. It just makes little pops sometimes.

I had the same problem and mine does that too. If its is not completly started, it will give a little backfire.

Good to hear your problem was fixed. I hope you used AC Delco plugs and wires or you may be having this problem agian very shortly.

Absolutely! NOTHING but GENUINE GM parts on my GM cars. My Dad retired after 50 years of "MR. GOODWRENCH." He boasts that he has GM stamped on his chest! Anything less than GM in our driveway and I am out of his last Will/Testament!

I got my plugs and my plug wires replaced and it really helped, unfortunately the car still backfires occasionally, but just when you're starting it. It's weird, because it doesn't produce exactly the sound I would expect when it does it. It just makes little pops sometimes.

There is a TSB Bulletin No.57-60-02 Dated August 1995
It refers to the pressure relief from the F I S on start up and is considered normal.

I have 2 95's and I found that the plastic lower intake gaskets shrink and can cause a surging problem mainly during warm up. I descovered this problem by accident. My stater needed replacing and when I inspected the intake gaskets I could see where they were leaking. I had been chasing that surge for a couple years. I had replaced plugs, wires, EGR valve. If you have access to a smoke machine it should show if your are leaking.
Carman999