2G Several Tries to Stay Started in Cold Weather

[jim97gst]

I've got a problem with starting the car in cold weather. It will turn over fine and start but then die immediately. After 3 or 4 starts it will stay started and run fine (it might idle low for a few seconds). Once it's warmed up a bit it will restart no problem. In warm weather there's no problem. Searching has led me to think it's the coolant temperature sensor. Today I connected to the ECU before starting and it read 52°F which was about right (it might have been a bit colder). Is this a valid test to see if it's working or do I need to do the test with different temperature water and measure the resistance across the sensor? If it was actually 40°F would that be enough off to cause this problem (I don't know for sure what the actual temperature was)?

 

[ChiTownHussla]

I think not

 

[Wildside22]

Just a few thoughts at 4:23am

a 10* shift should not cause a dramatic effect.

If your car starts then immediately dies the coolant would not have enough time to warm up in the engine. (unless its running a min or two then dies, then maybe it would)

Is it getting cold enough down there at nite time to form ice crystals in the fuel lines or in the tank?

You may have gotten some bad gas with water in it too? you could add some heat to the gas tank and see if that helps. (bottle as per instructions)

 

[luv2rallye]

Also check that your fuel pressure is being maintained at the rail while engine is off (should stay for couple days - otherwise leaky fpr or FP check valve).

 

[jim97gst]

It's not cold enough here for ice crystals to form.

It's possible there's water in the tank. I might try the heat.

I thought about the fuel pressure thing. I tried testing that by putting the key in the start position before cranking for 5-10 seconds to let the fuel pump re-pressurize the fuel lines. Is that a valid test? Also, would that be affected by cold weather?

 

[rough]

Could be a dirty injector causing a drip instead of a cone.

 

[jim97gst]

Using dsmlink, I turned the fuel pump on for several seconds before cranking and that made no difference. I think that eliminates the lost fuel pressure theory.

Is it worth doing the coolant temperature sensor test from the manual where you put it in different temperature water and read the resistance or is checking the reading from dsmlink good enough? I've read that there are 2 coolant temp sensors, one for the ecu and one for the dash gauge. I'm assuming dsmlink is giving me the ecu reading but maybe I'm wrong? Why would the factory service manual show you how to do that test when the dealer techs have access to a scanner?

Is there any way to test the leaky injector theory?

 

[pauleyman]

I think that eliminates the lost fuel pressure theory.

Not entirely. You will eliminate the need to pressurize the system first (if it is indeed leaking) but you may not solve a secondary symptom. If you have a leaky injector not only will it bleed down fuel presure it will bleed fuel into a cylinder. On first statup that cylinder is choking on fuel and can cause several startup tries before it's clear and then the car starts and runs as normal. This isn't theory, I've seen and fixed it first hand. Easy check. Drive the car arounhd. park it and let it get cold and sit. Pull the spark plugs one by one. If one (or more) of them are wet and smell like fuel you've found your problem. If not look elsewhere.

 

[jim97gst]

I suspect I have a bad coolant temperature sensor as I have a cold start problem when the ambient temperature is cold.

When it's cold outside, the car struggles to start, eventually starts, and then stalls. This usually happens 3 or 4 times and then it stays started, struggles for a bit, and then runs fine. There is a procedure for testing the sensor by measuring the resistance and checking the reading with the water temperature. I checked the temperature reading with DSMLink and it seems to be fine.

Could the sensor still be causing a problem?
Is DSMLink giving me the reading that the ECU sees or is it giving me the gauge reading?

 

[92AWDHX40]

http://www.dsmtuners.com/forums/newbie-forum/391482-replaced-coolant-temp-sensor.html

 

[jim97gst]

Hey thanks a lot man. I had a spare throttle body sitting around. I swapped it out and the problem is solved. My idle is better as well. I think the FIAV must have been bad.