Why does my 99 1500 run rough when cold?

Why does my 99 1500 run rough when cold?

Need a little help. I have a 99 1500 with 5.3L. When first started in cooler weather the engine misfires, runs rough. Then it will rev way up and back down to almost stall and sometimes it will stall and I half to restart the engine. After running for a while and the engine warms up it runs great.

What causes a bad start on a Vortec 5300?

Sounds like a bad intalke plenum gasket. When these gaskets fail they get a crack that lets air in causing a misfire. As the engine warms up the gasket expands allowing it to seal up. On a cold start spray a can of brake clean around the base of the intake plenum and see if the condition changes, if it does replace the gasket.

What’s the temp on a Silverado Vortec 5300?

Temps are in the low 60’s when I go to work & when I crank it it catches about the same time it normally does but it sounds like it’s only firing on about 4 cylinders for the first 10-15 seconds. After that it snaps out of it & runs fine.

Is it hard to start a Vortec in the morning?

I’m having a similar problem with mine right now, the more the temps drop off in the mornings, the harder it is to start the first time after sitting overnight.

Why does my GMC Suburban no start flooding itself out?

If I unplug one of the injectors it starts up and idles and I am able to plug the injector back in and it will idle as normal. If I try and start it with both injectors plugged in, it just cranks and cranks without attempting to start.

What kind of engine does a 1999 Silverado have?

Problem vehicle, 1999 Chevrolet Silverado 1500 5.3L V8 2WD with 351,000mi. I’ve read numerous threads on the rough idle cold start and the engine having some sort of intake leak and I don’t believe I have this problem, but I could be wrong.

What is coolant temp on GMC Suburban 5.7?

Sensor maintained the 1.15 psi for over 2 minutes and the voltage went up to 1.17 towards the middle of two minutes, however the voltage never dropped until I released the pressure. Coolant temperature sensor showed… approximately 2.5 ohms at room temperature and went down to 0.21 ohms in 190 degree boiling water.

Is there a problem with my Chevy Silverado?

Cold Hard CHEVY Start Problem Solved! Chevrolet Silverado Express Suburban Tahoe GMC – YouTube Cold Hard CHEVY Start Problem Solved! Chevrolet Silverado Express Suburban Tahoe GMC If playback doesn’t begin shortly, try restarting your device. Videos you watch may be added to the TV’s watch history and influence TV recommendations.