K1500 Suburban with 220K miles. Starting to have some issues but has been a problem free engine for 10 years. Local mech. ran quick diagnostic - P0300 (random misfire), P0420 & 430 (Cat. Converter below threshold) All good and well but his recommendation was to replace ALL of the coil-packs and plugs. - Seriously?? Prior to having test run, rough idle was occasional, check engine light was on, so I took it in. Since test, rough idle is constant and worse than ever. I can feel the misfire, sometimes bad, others hardly noticeable. Has not progressed to the point of stalling, but it won't be a surprise when it does. At 220K miles, I am not prepared to spend a fortune with a dealer/mech., but love this truck and want to keep it on the road. Can someone help me the "try this first" list of things to consider?
Suburban - P0300, P0420, P0430 on 2000 Chevrolet Suburban 1500
by ALH in Lakeland, FL on November 18, 2010
ANSWER by delane 72 garage and body shop , November 18, 2010
change plug wires and sparkplugs change converter put hi quilty converter on or you will have more problem with converter