Poor cold performance cause?

I've got a new (to me), 2002 Carrera 2 with 19K miles. Runs like a top except when is stone cold. For the first minute, I have to coax it to accelerate. By the first corner, everything is perfect??? One other symptom that may be related. Periodically when I start, there is a puff of normal colored smoke from the exhaust. This just happens in the first seconds of startup, thereafter it runs clean. This winter I put in new plugs and coils. I've never had the car in warm weather yet, and have only run it in 30 to 50 degree weather so far. I'm thinking maybe O2 sensors??? BTW, the oil consumptions seems normal and the tail pipes are not abnormally "sooty". Avg gas mileage is 20 mpg. Other than dead cold, it runs great. Thanks Larry

As far as "normal" colored smoke, I'm going to assume you mean blue smoke? Its normal for the M96 engine to burn a small amount of oil on start up (from the manual) which puts off a smoke with blue hue. Can't comment on the cold weather performance

Clean the intake port with carb cleaner or injector cleaner as a first step or at least inspect it. If there was a problem (repeated) with your O2 sensors it would light up a CEL sooner or later. Find someone with Durometric software and see what is happening under warm up conditions. Your running issue seems to be under closed loop conditions so something in the warm up area seems to be going on. I'm surprised you don't have a CEL but you may have a P code or two listed that is not a type that will light up a CEL but is still recorded for tech's to look at during the next service.

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Since I almost never attempt to drive my car off from a dead cold start but instead always let the engine idle until I hear the secondary air injection pump shut off I do not observe the symptom you report. However the times I do drive off from a cold start the engine does not run quite as good as well it does when I allow it a bit of warmup. And in both situations I drive the car the same and since the engine is cold (or nearly so for even after a few seconds to maybe a minute of idling the engine is no where near its operating temperature) this means being rather gentle with the engine. Have you tried letting the engine idle a bit after a cold start before driving off to see if this helps? If the engine runs poorly upon a cold start but perks up after about a minute this 'minute' is a clue, perhaps. The secondary air injection pump runs for around a minute (under cold start conditions) and if the engine runs poorly during this time and then perks up after this time this could point to a problem in the secondary air injection system. Still I'm hard pressed to imagine how this could effect the engine, since the air injection ports are *after* the combustion chambers. Another suspect is the intake air temperature or coolant temperature sensor is not reading right and the temperature readings are warmer than actual. The engine controller will be misled into thinking (as it were) that the engine is warmer than it really is and as a result deliver a leaner mixture than the actual temperature calls for. A check of the air temp and coolant temp sensor readings (with an OBD2 scan tool) might spot this. At a cold start, with the car/engine have sat unused for a long time (overnight is good) the two temp readings want to be close to each other and close to the ambient air temperature. If the O2 sensors are bad the engine controller should detect this. But it can take some driving (15 to 30 or more miles generally). However, I have to point out that at cold start the O2 sensors are not active because they are cold. Generally I have observed the sensors become active about the same time the secondary air injection pump shuts off. The smoking provided it is oil smoke not too dense and shortlived is normal. Treating the engine to short trips and not letting it get nice and warm exacrebates the tendency for these engines to smoke upon startup. Running too much oil, oil that is past its change by date, or the wrong oil, can oftentimes contribute to this smoking behavior. It is not normal if the smoking continues after startup or is very heavy at startup and engine misbehaves. Immediately after start up the engine runs rougher than usual, stalls, etc. The engine should not smoke at any other time either. Sincerely, Macster.

I've never really paid attention to rpms at start up but normally especially if in cold weather the rpms should be at least 1000 to 3000 rpms higher for an engine started in cold weather. Maybe watch and see what your rpms are. You don't list a qth....location so I have no idea what you mean by cold in saying cold start. If it's deathly cold like below 60F then yah most cars want a little warming up. Then if it's a tiptronic there could be valves wanting better flow from thinner fluid to actuate correctly and let the engine know the proper things that are going on down there. Of course this is an internet diagnostic from a warm place Even some spark plugs can care less to perform right in cold weather before warmed up and gaps can make the difference. Could also just be an old batch of gas needing a few cycling through refilling to cut the bad stuff out of there.

Got E10? Try some marine Sta-Bil. Worked for me on several cars w/ cold start trembles. Before you open your wallet to SWAG's. BD

Got E10? Try some marine Sta-Bil. Worked for me on several cars w/ cold start trembles. Before you open your wallet to SWAG's. BD

My Targa does this. My previous Toyota did it too. Does it run fine at higher revs, like Pac996 suggests? I'm not suggesting you run the car hard, just shift later while accelerating slowly. Does the car want to decelerate at revs below 2000?

I've had mine for over four years and it's always been a little cold-natured but after an initial couple of minutes, all is good.

I would not not judge the performance of any vehicle until it reaches operating temperature. Motors need a richer fuel mixture to start than at OP temp, oil is cold and thick, internal motor and trans components are cold and running clearances are usually greater when cold. There are too many things going on and changing quickly during the warm up process to expect it to run flawless. Sooty exhaust is a result of cold starting and a rich fuel mixture, a non issue. GL