hard start issue

[poweredx2]

I recently put a new battery in the svx and after its been sitting for a few weeks in near freezing temps I decided to take the car for a drive,after several attemps of popping back out the intake and exhaust it barely started after it started to smooth out and warmup you can cut the car off and restart it with ease.But after sitting overnight I gave up this morning trying to get it started.One thing I did notice was that the fans was on while I was trying to start the car so I replaced the coolant temp sensor with one from a 91 legacy i found at a salvage yard,that was probably bad also because my car is still hard to start,I have some extra ignitors and will order a coolant temp sensor tomorrow.Any ideas let me know what you think.I got a few days before I get the parts so I will check the fuel system first and go forth from there.

[immortal_suby]

Sounds like you are on the right track with the coolant temp sensor. You should check for any stored codes to be sure.

[1986nate]

Originally Posted by immortal_suby

Sounds like you are on the right track with the coolant temp sensor. You should check for any stored codes to be sure.

Yup, classic coolant temp sensor issues. When they fail or are failing, they cause the ECU to always see a warm engine condition, which includes not wanting to start when it is cold as it is not giving the right mixture for the cold temps. Also makes the fans turn on since the ECU is "seeing" a warm engine.

[Huskymaniac]

Originally Posted by 1986nate

Yup, classic coolant temp sensor issues. When they fail or are failing, they cause the ECU to always see a warm engine condition, which includes not wanting to start when it is cold as it is not giving the right mixture for the cold temps. Also makes the fans turn on since the ECU is "seeing" a warm engine.

That's interesting because I know someone once said that the ECU sensor drifts toward reading too cold like the gauge sender does when it ages. I thought that sounded backwards at the time and you are saying it is. So shouldn't he be able to start his car and grab OBD data to compare his readings to ambient to see if he is reading too warm? It takes a few seconds for the temps to rise, I would think.

[1986nate]

Originally Posted by Huskymaniac

That's interesting because I know someone once said that the ECU sensor drifts toward reading too cold like the gauge sender does when it ages. I thought that sounded backwards at the time and you are saying it is. So shouldn't he be able to start his car and grab OBD data to compare his readings to ambient to see if he is reading too warm? It takes a few seconds for the temps to rise, I would think.

I'm sure it is possible to err in that direction as well, but it seems as though it never does as every CTS problem I've heard of results in a no start in cold conditions. This also explains why you can shut the car off, and start it up and it fires away immediately. The coolant is still warm, giving the ECU a warm temp reading, or its defaulted to a warm reading which causes the ECU to give the right mixture and have no issues.

Another thing with a CTS that is failing, is you will get some bogging/surging until the car warms up on colder days.

The only way to get OBD data if it is a 95 or earlier is with a Subaru Select Monitor as far as I know. Those aren't something the average person has but that would be one way to check.

[poweredx2]

Also I realized the coolant temp sensor I replaced wasn't the right one,after reading some older post I replaced the single spade connector and should have replaced the dual spade connector,I think I can round one up today.If that get me back up running I will perform a good cleaning of any sensor contacts I can get my wire brush on.

[poweredx2]

Sure enough after removing the correct sensor and giving it a good cleaning with a wire brush my car fired up with no problems.The real test is to see how it starts after sitting overnight again in freezing temps,if that goes well I will clean the contact points on my other sensors and grounding point as well.

[Blacky]

Let us know how it goes. The '97 I'm picking up has similar cold weather issues.

[poweredx2]

I went out at 6 am and turned the key and the car started so easy that I was surprised but relieved at the same time.I guess the buildup on the cts is really a issue when the weather is colder.Now I am looking forward for some snow this weekend so I can put my snow tires and second gear start to work.Thanks for the help on this issue because the fans coming on in cold weather before even starting the car was a dead give away.

[poweredx2]

I started the car this morning also and drove it to work,I noticed that the car actually sounded a little smoother warming up than before I ran into the coolant temp sensor problem,again thanks for the help.

[sd2649]

I have the occasional hard start and sometimes a surging while driving with a cold engine. Where is this sensor located? Pic?

[North Ursalia]

It's in the coolant crossover pipe on the driver side of the engine. Don't have a pic handy though.

[North Ursalia]

Found a pic on eBay of all places- the sensor is on the left bottom edge of the crossover pipe in the attached pic.

[sd2649]

Thanks! How hard is it to get that bugger out of there?

[North Ursalia]

Haven't replaced one yet myself, but it probably follows the Subaru Law Of Inverse Difficulty; the cheaper the part is, the harder it is to replace. Since the sensor is about $30, it's probably a hoot to replace it !