SOLVED: Rough idle at startup in cold weather

BUNGNATI

MEMBER
1935 GMC YUKON

Solved!
The intake manifold gasket was bad. Replaced them and runs fine in cold weather.
GM is aware since they issued a TSB about it PIP3232B
Dealer wanted $700 to replace it. Did it myself in 4 hours for $45.
Hope this helps.
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I have a 2001 Yukon XL 1500 5.3l 323 cid with 103,000 miles. Recently I started the truck in 15F and idled very rough shook the truck and everything. Tried giving it gas and it wanted to stall when I did. The MIL started flashing then went out. The truck ran perfectly when it warmed up alittle. This happened the next day 25F but not as bad or for as long. I also had the computer throw a Evap code 3 days before and a similar evap code about a month ago. Now I started it at about 50F and started and ran fine. All sensors are reporting to the computer and seem to react properly by the OBDII scanner at 50F (dont know about colder temps yet)
Any help would be great.
Thanks,
John

3 Replies

RASMATAZ

MECHANIC
75,992 POSTS

Won't hurt to check the TPS its job is to enrich fuel during initial cold starts it takes the place of a carb. Choke Might also want to investigate the IACV.

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Wednesday, November 28th, 2007 AT 12:30 AM

BUNGNATI

MEMBER
3 POSTS

Wouldnt the IACV cause other idle problems even when engine is warm? The TPS seems fine it detects even slight movements of the throttle and I have read the sensor data with the obd port. I also saw a post about a sierra 5.3l with similar problem

https://www.2carpros.com/forum/gmc-sierra-1500-4x4-rough-cold-start-in-cold-weather-vt70029.html

does the responder mean the IACV.

Thanks.