Hard Start + Rough Idle Warm

[mistermaster]

I just jumped into the Chevy word with a 98 454.

Sometimes the engine takes several seconds to start. Sometimes it fires right up. I can't seem to find a rhyme or reason as to when it does one or the other. I have done the "key dance" (run position/off repeated) several times and that doesn't seem to change anything.

Also once warm, the engine doesn't run smooth. I wouldn't say rough, but just not smooth.

I'm thinking it's a sensor, but was looking for some direction on things to try.

 

[run96k3500]

I was fighting this for years. Tried everything. Turned out to be a blow intake manifold gasket. It was the lower one. So my thought is that the motor is sucking in air through there and the sensors in your intake aren’t aware so the engine is running to lean.


Sent from my iPhone using Tapatalk