Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum banner

1 - 7 of 7 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter #1
Ive had a p0171 bank 1 system to lean, everything seems to check out fine and my only drive issues are that when i first start it runs rough for about 3 to 4 seconds. On start up itll be around 1k for 1 second then drops really low and idles really rough for about 3 seconds and then it returns to 1k idling normally and it only happens on the intital start up for the day. Its been cold in arkansas so i thought the cold was causing it but its gotten a bit worse.
 

·
Registered
2004 gmc envoy_slt
Joined
·
2,444 Posts
First of all, when was the last time the throttle body cleaned?
Running lean can sometimes be caused by a leak around the intake manifold gasket (possibly loose hold-down bolts), low fuel pressure, lazy upstream O2 sensor.
 

·
Registered
2004 chevy trailblazer_ls
Joined
·
333 Posts
You could also check the SAIS. Mine (2004) needed a valve, the one on the passenger side above the exhaust, that fixed it.
 

·
Registered
2006
Joined
·
2 Posts
All those things are possible culprits but I would do 2 things first and in this order.

Check your fuel pressure should be above 50 psig forget the value right now. Chased all those things listed but it turned out to be fuel pump. Had 38 psig but truck ran good. The computer adjusted for weak pump by holding the injectors open and that threw off the fuel trims. Got the P0171 code.

Went away after the fuel pump change MPG went from 13 on the highway to 17+

Did all that other stuff 1st because it ran good.
 
1 - 7 of 7 Posts
Top