'02 Tahoe LS Rough Cold Start

[dmperfection]

A couple of months ago, my Tahoe started running rough at cold start in the mornings, but runs fine once warmed up. The problem is getting a little worse, and having to give it a little gas in the mornings to get to a smooth idle, but the rough idle still goes completely away when warm. This only happens in the mornings. I've got about 118k miles on this baby, and since I hadn't replaced plugs and wires, I went ahead and took of that first. After replacing plugs and wires, I'm still having the same problem. I prefer to do the research myself and try to fix the problem without having to go to a shop, and get a little education in doing so. Can anyone give me some advise on what to look for next or other possible culprits?

I'd appreciate any help or advise anyone can provide.

Thanks everyone!

 

[JKmotorsports]

Try cleaning out the throttle body. Gunk builds up on the edges of the throttle plates and in the air bypass passage which will cause a rough idle when cold.
Another possibility could be a small vacuum leak from the intake manifold gasket. A small enough leak will cause a rough idle when cold. Then once it starts to get warm, the gaskets will expand some and close off the gap.

 

[01smellytahoe]

I was thinking throttle body also, take it apart and get the carbon outta there

 

[Rivieraracing]

I had the same problem myself, then I read on here to use some seafoam deep creep and spray the crap out of the TB, haven't had the problem since.

 

[dmperfection]

I had the same problem myself, then I read on here to use some seafoam deep creep and spray the crap out of the TB, haven't had the problem since.

I read other posts, and even took a look at the Seafoarm application; funny stuff on YouTube (all the smoke and all), but don't know if I'm ready to try it myself. Maybe as a last resort. Thanks for the input.

Try cleaning out the throttle body. Gunk builds up on the edges of the throttle plates and in the air bypass passage which will cause a rough idle when cold.
Another possibility could be a small vacuum leak from the intake manifold gasket. A small enough leak will cause a rough idle when cold. Then once it starts to get warm, the gaskets will expand some and close off the gap.

JK - I'm planning on cleaning up the TB this weekend, but I've read several posts that lead to the intake gaskets leaking. I hooked up a MasterTech scanner, read codes PO171, PO174 (lean fuel mixture) and PO300 (random misfire); this combination seems to be a sure bet on intake gaskets, unless O2 sensors have gone bad or stray vacuum leak. I'll take care of the easy stuff first; clean out the TB, then consider replacing intake gaskets.

Thanks to all for input; I'll report back when I get this resolved.

 

[Rivieraracing]

I actually was talking about cleaning out the throttle body like JK was saying, not seafoaming the motor. Cleaning out the throttle body did solve my problem completely, hasn't had the problem since I cleaned it. I was kinda nervous about giving my motor a "seafoam bath" but today I broke down and did it, curious on if it will help my Yukon out, sure did smoke alot (nothing funnier than a nice Denali with a smoke screen down the highway). :thumbsup: