2009 SLT Yukon rough idle for 30 seconds on cold start

[dro45]

2009 Yukon Flex Fuel. I start it up and back out of my driveway. Idle is very rough and missing for less than 30 seconds. After that, it idles and drives fine until the next cold start the next morning. New plugs and wires. Injectors serviced.

Really appreciate the help!

 

[Foggy]

Try cleaning the MAF and Throttle body first...
Then my next step might be to verify fuel pressure and check intake manifold
for possible (probable) vacuum leak...

 

[swathdiver]

2009 Yukon Flex Fuel. I start it up and back out of my driveway. Idle is very rough and missing for less than 30 seconds. After that, it idles and drives fine until the next cold start the next morning. New plugs and wires. Injectors serviced.

Really appreciate the help!

Mine has always been a little cranky in the morning. I let the oil course through the galleries before putting it in gear, 5 to 10 minutes always. This way she's nice and cool inside and ready for anything.

 

[dro45]

Try cleaning the MAF and Throttle body first...
Then my next step might be to verify fuel pressure and check intake manifold
for possible (probable) vacuum leak...

Thank you. I forgot to mention vacuum leak checked and OK. I'll take a look at the MAF and throttle body. That's a relatively easy and cheap thing to do. Thanks again.

 

[dro45]

Mine has always been a little cranky in the morning. I let the oil course through the galleries before putting it in gear, 5 to 10 minutes always. This way she's nice and cool inside and ready for anything.

Thank you. Mine was always ready to go as soon as I touched the starter, up until a couple months ago.

 

[wsteele]

If you have a scanner of any sort, it would be good to check for codes. Also it would be very helpful with a scanner to know if the rough running was only in open loop, or if it stopped before you get to closed loop. In addition, during the rough running period, what the fuel trims look like and what they look like after the rough running stops.

 

[swathdiver]

Thank you. Mine was always ready to go as soon as I touched the starter, up until a couple months ago.

You can also put a torque wrench on your intake manifold bolts.

 

[donjetman]

Spark plug(s) wet with oil? Needs a catch can and the updated valve cover?

 

[petethepug]

Gotta verify what your fuel pressure is at idle and under load or it’s scan time. Have you replaced the f/p or is it a generic fuel pump? So many things it can be without using the power of the scanner force.

 

[dro45]

If you have a scanner of any sort, it would be good to check for codes. Also it would be very helpful with a scanner to know if the rough running was only in open loop, or if it stopped before you get to closed loop. In addition, during the rough running period, what the fuel trims look like and what they look like after the rough running stops.

Yes, I have and am not getting any codes at any time. Thank you!