Diagnose this: poor starting when cold

[mikec03]

I have a 2.2, '95 Soob w/ 188K mi. This winter, it's starting on 3 cylinders and sometimes not at all at temperatures minus 20 F. After starting, it runs fine. The coil, wires, and spark plugs were all OEM with only 15K. I changed the coil and spark plugs anyway but it didn't have any effect. The wires seem OK. I hate to change them too.

 

It seems like it has to be electrical because it runs fine after it starts. I didn't have this problem in prior winters. Any ideas. What could I try to diagnose it?

[Fairtax4me]

Might be a CTS issue. If you have a spare try swapping it out. Try searching the boards here and you should be able to find how to test it.

I'd also try some strong fuel system cleaner. (it never really hurts)

Beyond that...

Check the resistance of each of the spark plug wires when they're cold with an ohmmeter. They should all be fairly close in measurement, if not then get a new set.

[nipper]

Coolant Temp Sensor.

 

How old is your timing belt by the way?

 

 

nipper

[mikec03]

The timing belt is only 10K mi old. I should have mentioned that there are no codes and that the old spark plug looked fine. Also, the way the post was printed was not the way I typed it. To be clear, at a temperature of 20 degrees it starts hard with maybe 3 cylinders; at a temperature of 10 degrees, it starts very hard on 3 cylinders maybe requiring a jump after running the battery down. At a temperature of 30 degrees and above, no problem.

 

I don't see why the temperature sensor would cause it, but it's something I never thought of and it's cheap to replace.

[nipper]

There are very few things that will make a subaru not start or hard to start. this is the most common. CTS tells the ECU how cold the engine is. The ECU looks at its program and says for zero degreees We need X amount of fuel and spark at X time (to make it simple). Now if the temp senser gets a dead spot in it, the car may not get enough fuel for the apropriate engine temp. this can cuase a hard start from fuel stravation or flooding. The reason its three vs 4 cylinders may not really mean anything if it starts normally at all other times. one cylinder may have a litle weaker spark, plug, or injector, compression etc.

 

nipper

[danbennett2u]

Try turning the key to on when the engine is cold. Check to see if the fans are running. If they are running when cold then the Coolant Temperature Sensor is definitely suspect. If this is the case the computer thinks the engine is hot so it doesnt provide the rich mixture needed when the engine is actually cold.

[nipper]

When the car starts, is there a belch of smoke?

[mikec03]

Is there a lot of smoke when it finally starts? There is some, but in the cold weather, the condensed water vapor tends to obscure the amount.

 

I'll go to my U-pull-it junkyard Monday and see if I can get a CTS. Thanks for the advice. Thankfully someone put pictures on the internet or I would never be able to find the CTS.

[Gloyale]

How are you determining it is starting on 3 cylinders?

[Gloyale]

The wires seem OK. I hate to change them too.

 

 

What does "seem OK" mean? Did you test there resistance with an OHM meter?

 

Or did you just look at them?

 

They should eb replaced every 30k miles.

 

If they are red "Yazaki" wires, then they are the originals and DEFINATELY need replaced.

[mikec03]

Just to summarize and finish off this old post, I did change the CTS [the junkyard didn't even charge me for it]! But it didn't seem to make any difference.

 

So now I'm giving the car a couple tankful treatments of Techron. I'm hoping that one of the fuel injectors is partially plugged and the treatment will clean it out. But the weather in Wi is warming up so there probably won't be any real cold mornings that I can check it out. I'll find out next winter.

 

Thanks for all the help and suggestions.