1999 sierra hard warm start and Rough idle

[Richw001]

I've got a 1999 GMC sierra 4x4, for about the last 6 months it has been hard to start when engine is warm (starts fine when cold) and for about 2 months it has been idleing very rough and getting worse. I've read some of the threads that say egr, but i'm not sure where it is or what it looks like. Also I bought the GM brand intake cleaner but I'm not sure on how to use it (not in a spray can). Also, check engine light has been on for about 1 year read codes and says evap control malfunction and newest code was for o2 sensor, i changed th eo2 sensor and didn't run any better.

Any help would be greatly appreciated.

Rich

[Richw001]

Bump!

[KICK]

I've got a 1999 GMC sierra 4x4, for about the last 6 months it has been hard to start when engine is warm (starts fine when cold) and for about 2 months it has been idleing very rough and getting worse. I've read some of the threads that say egr, but i'm not sure where it is or what it looks like. Also I bought the GM brand intake cleaner but I'm not sure on how to use it (not in a spray can). Also, check engine light has been on for about 1 year read codes and says evap control malfunction and newest code was for o2 sensor, i changed th eo2 sensor and didn't run any better.

Any help would be greatly appreciated.

Rich

 

<{POST_SNAPBACK}>

 

 

 

 

if you hook a vacuum gage to intake manifold with it idling and you have low manifold vacuum, that is an indication of a stuck open EGR valve.

 

EGR valve stuck open acts like a big vacuum leak and engine will run fairly well at higher speeds but will either run very rough or stall at idle.

 

it could be other things too.

 

is it running on all cylinders???