Hard COLD start, bad ISC or something else??

tsi1991awd · 10-09-2008, 02:28 PM

91 Talon TSI AWD...it is hard to start in the morning. Its been cold here lately (WA) and it takes 3 or 4 times before the car starts. Then when it does start sometimes it'll stutter at a really low RPM before it starts warming up normal.

This is only on the first start of the day. Every other time it starts with no problems at all.

What could it be? I'm changing the spark plugs this weekend and the fuel filter next weekend. I have read the coolant temp sensor can cause it to have a hard start but this is only one time. It will start fine every other time. It idles fine, drives fine. Doesn't stall, die, etc. So I have no idea....

interex · 10-09-2008, 03:09 PM

I'm almost positive it's the spark plugs. Once you get them changed you should be good to go.

Boost92awd · 10-09-2008, 03:11 PM

Probally would hurt to go to autozone and have them check the battery and alternator.

tsi1991awd · 10-09-2008, 03:16 PM

I'm buying the plugs after work today and going to put them in when I get home. BPR6ES....hopefully it takes care of the problem

Also, I should've mentioned that I just changed the alternator this past Saturday...was giving me the infamous glowing gauge lights. All better now though! Battery is only a year old but I checked it at Autozone before I did the alternator.

talon187 · 10-09-2008, 03:24 PM

I had the same problem it tuned out to be my coolant temp sensor the colder it got the harder it was to start the car

96mitsugsx · 10-09-2008, 03:29 PM

CHeck your FPR. Maybe it's not holding pressure overnight.

tsi1991awd · 10-09-2008, 04:09 PM

Quote:

Originally Posted by 96mitsugsx

CHeck your FPR. Maybe it's not holding pressure overnight.

How do I test it?

Sam@RRE · 10-09-2008, 04:24 PM

the fpr only controls the fuel pressure while the car is running, its supposed to keep the pressure in the rail at a steady point at atmospheric pressure and lower pressure for every inhg and raise pressure for every psi. Has nothing to do with holding pressure over night. I second temp sensor. Check the connections on it, the car has two sensors on the housing, one single prong connector for the gauge cluster, and a two prong connector for the temp signal to the ecu. Seen the wiring fall apart, that's the most common problem.

tsi1991awd · 10-09-2008, 04:36 PM

Quote:

Originally Posted by Sam@RRE

the fpr only controls the fuel pressure while the car is running, its supposed to keep the pressure in the rail at a steady point at atmospheric pressure and lower pressure for every inhg and raise pressure for every psi. Has nothing to do with holding pressure over night. I second temp sensor. Check the connections on it, the car has two sensors on the housing, one single prong connector for the gauge cluster, and a two prong connector for the temp signal to the ecu. Seen the wiring fall apart, that's the most common problem.

I will check it later tonight when I do the sparkplugs. I just changed the radiator, thermostat and hoses this past Saturday and didn't notice anything. But then again I didn't look that good either.

What do I need to do if the wires are broken? Splice new wire? Is it the temp sensor itself that goes bad or is it the wires to the sensor?

Raptoreborn · 10-09-2008, 04:49 PM

Quote:

Originally Posted by talon187

I had the same problem it tuned out to be my coolant temp sensor the colder it got the harder it was to start the car

I agree if it's not ignition. Check the coolant temp sensor.

JayRolla · 10-09-2008, 05:01 PM

Coolant temp should through a CEL. Do you still have the fuel pressure return solenoid( I think thats what its called). Its a solenoid that helps keep fuel pressure after turning off the car. Usually people remove them. Only issue it causes the fuel system must prime every start.

stefanOst · 10-09-2008, 05:28 PM

When I had this problem it was a coolant temperature sensor like others have mentioned. Once the car would finally get started it would run fine, and start easy once warmed up. Would throw a CEL after running for a minute or two.

r1991_4g63t · 10-09-2008, 05:36 PM

had this problem last winter when it would get under 20*. had someone tellin me to check the temp sensor but i wouldnt listen, after two weeks i took a multimeter and checked it, it was bad, basically telling the car it was 240* when it was 2* outside

interex · 10-09-2008, 06:58 PM

Wow people just throw out weird suggestions. If the car turns over, it cant be the battery. If the coolant temp sensor goes out it will start but idle high on first start. :/

r1991_4g63t · 10-09-2008, 07:29 PM

Quote:

Originally Posted by interex

Wow people just throw out weird suggestions. If the car turns over, it cant be the battery. If the coolant temp sensor goes out it will start but idle high on first start. :/

you wanna bet? you obviously never had any training as a mechanic or you would know that when the computer sees the temp sensor at 240 it gives a different amount of fuel the it would if it was at 20, thus causing the no start when its 2* outside. a temp sensor, for the ecu not the guage, will absolutly cause a no start if its cold enough outside.

tsi1991awd · 10-10-2008, 12:41 AM

Replaced plugs, started strong...we'll see what happens in the morning.

interex · 10-10-2008, 01:05 AM

Sure, I've had a great amount of automotive mechanical experience... And I also just tested this theory by taking my water temp sensor out and 1st used a can of compressed air (upside down) to spray and chill the sensor, car fired right up but idled really high. Reset the ECU and then used my butane torch to heat it up, car fired right up and idled lower, reset it again and unpluged the sensor and the car fired up and threw a cel instantly. Hmm, Can't see where I was wrong when I made my previous statement.

BrokenTsi · 10-10-2008, 01:58 AM

I had a bad coolant temp sensor that would do this before. Sometimes the car wont want to start at all.

r1991_4g63t · 10-10-2008, 04:27 AM

Quote:

Originally Posted by BrokenTsi

I had a bad coolant temp sensor that would do this before. Sometimes the car wont want to start at all.

DING DING DING we have a winner, thats what im trying to say, it wasnt everytime it started usually just first thing in the morning when its been sitting in -20* weather. i replaced the 2 wire coolant sensor and it fixed it

interex · 10-10-2008, 05:31 AM

So, over night I sat my temp sensor in a little cup with water and put it in the deep freezer, froze solid. I just now went out and plugged it in while incased in the ice cube it froze inside of and tried to start the car. The car fired right up, and I checked and the tempature of the sensor and it was 4 degrees fahrenheit. Maybe my temp sensor is just not defective or maybe not "as worn" as others... But still never seen a car NOT start due to one missing, or malfunctioning. Maybe it depends on the car, the ecu, or the sensor itself. I'm the lucky one!

hdoerr · 10-10-2008, 05:41 AM

Our harness plug was loose inside the plastic. Maybe it just wasn't making a good connection. With out the temp sensor the ecu sees -54C and that richens the fuel so much that the car is hard to start or even run all together.

interex · 10-10-2008, 05:55 AM

I don't dis-believe that at all. I'm just saying I personally have not had that issue, or seen it happen around here. On my GM I know if I unplug the coolant temp sensor it just throws a CEL and lets the car start at a default stage.