Slight stumble on cold start

[xford]

2006 LS V8 - recently started to have a slight stumble for a few minutes at cold start - goes away once warmed up. No codes via OBDII or dash lights. Its odd but it seems like I can feel it thru the accelerator pedal while driving right after start up - a bit of vibration/feedback. Aside from possibly a failing COP(s) other likely candidates? Not long ago manifold was removed to replace a cooling system hose. Thx

 

[joegr]

You know that the gas pedal is electronic, right? There is no physical connection to the engine, only to the firewall.
Intake air (vacuum) leak is the first think to come to mind. Very small ones sometimes seal when the engine is warm, and leak when it is cold again.

 

[xford]

You know that the gas pedal is electronic, right? There is no physical connection to the engine, only to the firewall.
Intake air (vacuum) leak is the first think to come to mind. Very small ones sometimes seal when the engine is warm, and leak when it is cold again.

Yes on the electronic pedal - maybe the slight vibration is felt thru the physical connection to the firewall?

Since the manifold was recently removed to replace a coolant hose would it be logical to consider that gasket as a likely culprit for some type of small leak - would also think that could seal fairly quickly with motor temp increase

 

[Diesel980]

2006 LS V8 - recently started to have a slight stumble for a few minutes at cold start - goes away once warmed up. No codes via OBDII or dash lights. Its odd but it seems like I can feel it thru the accelerator pedal while driving right after start up - a bit of vibration/feedback. Aside from possibly a failing COP(s) other likely candidates? Not long ago manifold was removed to replace a cooling system hose. Thx

I would suspect a bad EGR Valve.

 

[joegr]

I would suspect a bad EGR Valve.

Wouldn't it trigger a code for excess flow or flow when it was closed?