Engine bucking

KEVIN WOIDAN

MEMBER
1997 CHEVROLET SUBURBAN
5.7L
V8
4WD
AUTOMATIC
140,000 MILES

For the last three weeks after initial warm up upon acceleration the engine bucks. About fifteen minutes goes away. No stalling had plugs replaced was told wires are good had cap and rotor replaced four months ago and fuel filter replaced. Check engine lite comes on mechanics check code. 02 sensor and misfire. Fuel, pressure was also checked. Only happens after initial startup. The vehicle is in excellent condition. The soaked all high tension components also. Including compression test shows normal. Can you help?

Wednesday, September 27th, 2017 AT 2:24 PM

1 Reply

HARRY P

MECHANIC
2,292 POSTS

In my experience, those engines are picky about spark strength. Generally, I suggest using only AC Delco plugs and wires in GMs. At that many miles, and twenty years old, if the wires have never been changed, they are not right. They can look fine, but still not be delivering a full strength spark.

Also, at twenty years and 140,000 miles, it would not be a bad idea to replace the fuel filter. https://www.2carpros.com/articles/how-to-change-a-fuel-filter

Finally, take the cap and rotor off and clean off any corrosion and make sure there is no moisture. The design of that distributor can allow condensation to buildup inside the distributor, causing rough running and/or misfiring. I take the cap and rotor off of my Blazer occasionally (same design, except for a six cylinder engine instead of a V8) and clean off the contacts and make sure it is dry. That alone has eliminated a P0300 code before.

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