Starting when cold: Issues

[Nate94XE4x2]

I'm somewhat of a fuel-injected rookie. Starting this winter, when I go to start the truck, it fires right up for a few moments before the engine speed reduces, sputters for a few seconds, and then resumes idling. The colder it is, the worse it is, and it will die if it's REALLY cold. It smells pretty rich in the process.

 

What do I check/fix/replace/kick?

[Precise1]

My truck does a similar thing, but it never dies (not cold enough here I suppose). I never looked into it as it isn't a real problem. Running rich is normal, because I believe the ECU runs in open loop mode until it warms up, circa 160+ degrees IIRC. It couldn't hurt to check the resistance/voltage outputs of the O2, TSP and scheck the MAF wiring/connector.

 

B

[Kingman]

Hmmm. Yeah at 150F the computer goes in to closed loop mode and starts taking readings from the various sensors, mainly the O2 sensor. Before that it's not a part of the system. I believe in open loop cold start, the computer takes a reading from the ECM Coolant Temperature Sensor and Fuel Temperature Sensor to get a "baseline" for the cold idle enrichment.

 

TPS shouldn't be an issue with cold weather, it's only a 3-way switch for idle, half throttle, and full throttle.

 

I would check your cap and rotor in the morning to see if there's any condensation inside or a little hairline crack anywhere. Definitely wiggle your MAF wiring around a bit as well to see if it changes anything. It may also help to clean it with rubbing alcohol and a q-tip, or actual MAF cleaner. Oh and if that stuff is flammable, don't spray it in to the air box before the sensor unless you want your engine compartment on fire...