Bad Spark

Awitt · December 6, 2015

Hi group. I own a 98 GMC Sierra SLE K1500 5.7 Vortec. It's got over 220,000 miles, I recently did a major tune up. Plugs, wires, cap, rotor, oil, oil filter, air filter, cabin filter... It's been running like a top, for over 9 months. I started it the other morning after it was of all night, & it idled like crap. I shut the porch lights off & looked under the hood, it looked like the 4th of July. Sparks are running up & down the wires & all over. I know the wires are in the correct order because I only pulled them one at a time to replace them. The same with the plugs, & they are properly gapped. The cap & rotor will only go on one way. The wires are lifetime warranty & I replaced them last night. Yet it still is running like crap. Anyone got any ideas?????...

Squirrely · December 9, 2015

Possibly IAC or TPS.

Both will cause running issues and at 220K, they may need to be replaced. My guess is the IAC.

Awitt · December 9, 2015

Squirrely, Thank you for your reply. I stopped by my local O'Reilly Auto parts, ran my scenario by the assistant Mgr & he was stumped. He asked the Mgr & he said try the cap & rotor. I told him what was going on & how new they were, he said he would warranty them, so I agreed & it's running normal now.