2001 Tahoe, doesn't want to stay running in cold

[TURNz]

It starts right up and surges at 1800rpm or so for maybe 10 or 15 seconds, then it settles down to about 800rpm idle and tries to die. If I keep RPMs up a little with the peddle for a minute, it seems to help.

IAC valve?

It was 9degrees F this morning, but it did it around 20 degrees the other day. It's not every time though.

 

[rockola1971]

Getting a check engine light? If so what are the codes? Sounds like the typical leaking intake gasket symptoms. Try to snug down intake manifold bolts and see if it goes away or gets better at idling.

 

[Doubeleive]

most likely intake gasket or fuel pump pressure, if it runs it has spark, if then dies it either has to much or not enough air or not enough fuel. that would be the first things to chase down.

 

[TURNz]

most likely intake gasket or fuel pump pressure, if it runs it has spark, if then dies it either has to much or not enough air or not enough fuel. that would be the first things to chase down.

No engine light, but two pending codes.

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[Doubeleive]

those codes could be from to much fuel or not enough (maybe), I would do a leak test on the manifold and a fuel pressure test, fuel pressure test first since it wont even stay running, could even be a clogged cat, what is the mileage and any service history? you have to take all that into consideration, the fuel pumps on these nbs in general are made for 100k so if it has a lot more mileage than that and the fuel pump has not been changed that would be my first suspect. I could be way off base but I would def do a fuel pressure test to rule that out.

 

[rockola1971]

those codes could be from to much fuel or not enough (maybe), I would do a leak test on the manifold and a fuel pressure test, fuel pressure test first since it wont even stay running, could even be a clogged cat, what is the mileage and any service history? you have to take all that into consideration, the fuel pumps on these nbs in general are made for 100k so if it has a lot more mileage than that and the fuel pump has not been changed that would be my first suspect. I could be way off base but I would def do a fuel pressure test to rule that out.

How do you get a too lean code from too much fuel? You can get a too lean code from TOO MUCH AIR (Leaking intake gasket or low fuel pressure will both cause a 0171/0174)

 

[Cattivo]

I've been getting those same exact codes since the temperatures dropped below 40 degrees. The truck starts fine but has no balls whatsoever...I'm pretty sure it's a combination of a leaking intake manifold gasket, bad fuel pump/filter and clogged cats

 

[Doubeleive]

How do you get a too lean code from too much fuel? You can get a too lean code from TOO MUCH AIR (Leaking intake gasket or low fuel pressure will both cause a 0171/0174)

if the fuel is being dumped into the cat from not being burned properly it will throw a lean code and burn your cat out, I used to go thru them about once a year, never really could figure out why on my 2000 but they were burnt from fuel, they were cut open to inspect for warranty and denied by the manufacture because of that.

 

[rockola1971]

if the fuel is being dumped into the cat from not being burned properly it will throw a lean code and burn your cat out, I used to go thru them about once a year, never really could figure out why on my 2000 but they were burnt from fuel, they were cut open to inspect for warranty and denied by the manufacture because of that.

If the A/F is so screwed that raw fuel is being dumped into the cats why would the o2 sensors detect a lean condition instead of a rich condition. That makes no sense.

 

[Doubeleive]

If the A/F is so screwed that raw fuel is being dumped into the cats why would the o2 sensors detect a lean condition instead of a rich condition. That makes no sense.

my bad, mine was throwing a rich code like p0172/p0175