Rough idle and P0171 in the cold (below freezing)

[nittanydoug]

I've been getting a rough idle while in drive and stopped when my 05 base vibe is cold. I'm talking below freezing. Today it threw the p0171 code. It's thrown it a couple times in the year plus since I've owned it but could never find the reason. I've clean the MAF sensor and throttle body plate several times and run Lucas injector cleaner through it. This weekend after noticing the rough idle I did another cleaning. I just found the Toyota TSB about the intake manifold gasket issue.I have a decent reader, what should I be looking for values in test mode to see if I have the gasket issue?I'm pretty handy in the garage as I do most repairs myself. Is this something that can be done by the backyard mechanic? Doesn't look bad from the TSB. Thanks for any help.

[wt2ga]

CausesA code P0171 may mean that one or more of the following has happened:•The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters may cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.•There could be a vacuum leak downstream of the MAF sensor.Possible SolutionsPossible solutions include:•In the vast majority of cases, simply cleaning the MAF sensor does the trick. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling•Inspect all vacuum and PCV hoses, replace if necessary•Check for a dirty fuel filter and proper fuel pressure

[nittanydoug]

yeah, read all of that in the forums here. I've cleaned the MAF sensor. Seems like this is really related to the cold and the Toyota TSB seems to address it just don't know if it's what I have.

[nittanydoug]

this is the tsbhttp://forums.genvibe.com/zero...1.pdf

[lovemyraffe]

Just change the intake manifold gasket. It's fairly simple to do and the gasket itself is inexpensive.

[nittanydoug]

yeah, looked on Rockauto and the price is cheap. I think shipping is more than the gasket. I might call my toyota dealership that's near me and see if I can get it from them. I know it will be more but might be comparable out the door.

[nittanydoug]

Got the gasket from the local toyota dealer for a whopping $6.11. Took about 30 minutes mainly cause I scrambled trying to find something to catch the coolant. I'll find out tomorrow if it worked.

[wt2ga]

[nittanydoug]

Seems to be running A-Ok. Of course last night it wasn't in the teens like before but still below 32 and no rough idle.

[nittanydoug]

The gaskets were definitely a new design. The original was a flat gasket. The new one has more of a profile that projects forward and back. There's not much to doing the change either.