Hard COLD start, bad ISC or something else??

[tsi1991awd]

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....

 

[tsi1991awd]

I'm not sure of all this coolant sensor talk but I suppose that could be it. How much do the sensors cost? I'm about to go leave for work, so this will be the test. The sparkplugs that I took out didn't look like they were too bad. They had a white coating all over the tip and electrode, but it didn't look like it was worn down or anything. BUT they were cheap 25 cent plugs...the champion plugs. Put in the BPR6ES and when I fired it up last night, after it had been sitting for 4-5 hours, it started really strong and on the first try...so we will see whhat happens this morning and ill let you all know.

 

[r1991_4g63t]

I'm not sure of all this coolant sensor talk but I suppose that could be it. How much do the sensors cost? I'm about to go leave for work, so this will be the test. The sparkplugs that I took out didn't look like they were too bad. They had a white coating all over the tip and electrode, but it didn't look like it was worn down or anything. BUT they were cheap 25 cent plugs...the champion plugs. Put in the BPR6ES and when I fired it up last night, after it had been sitting for 4-5 hours, it started really strong and on the first try...so we will see whhat happens this morning and ill let you all know.

the sensors are usually like 10-15 bucks. not positive thats your problem, but yours is doing pretty much what mine did when it went out

 

[tsi1991awd]

So the sparkplugs didn't change much. It wanted to start better than usual but didn't until the 3rd try. Is that coolant sensor 10 or 15 at the dealer or somewhere like Autozone or NAPA? Also, is there a way to test the sensor and see if its bad?

 

[r1991_4g63t]

So the sparkplugs didn't change much. It wanted to start better than usual but didn't until the 3rd try. Is that coolant sensor 10 or 15 at the dealer or somewhere like Autozone or NAPA? Also, is there a way to test the sensor and see if its bad?

you can test it with a multimeter that will read the resistance, i'd have to look to find out how many ohms its supposedd to be for that.

but yeah i got mine aftermarket since the dealer told me it would be two weeks.

 

[tsi1991awd]

Where did you get it from?

Also when installing it, can you just screw it on or do you need to use tape around the threads?

 

[r1991_4g63t]

Where did you get it from?

Also when installing it, can you just screw it on or do you need to use tape around the threads?

i got mine from oreillys, but i dont think they have them in WA. no matter all the aftermarket companies sell the same sensors in different branded boxes but the sensors themselves come off the same line.

i;d have to go look at it but i think the new one came with some sealer crap on it already

 

[David Marshall]

ive got a 1990 gs that did the same thing. it refused to start when it was cold out. once i got it started it would stumble between 400-700rpms and then stall. i ran over wiring diagrams and checked every connection, then ran a diagnostics tool to find out that the coolant temp sensor was reading -164 degrees. you might want to open up your pcm and check for and bad spots on the circuit board or blown transistors. i know a guy in florida that repaired mine for $160. i have the adress if you want it. just let me know. good luck with your tsi!

 

[tsi1991awd]

I guess its worth a shot. Wouldn't hurt anything to replace the sensor. If its not it, then at least I know its not gonna go bad for a while!

It seems like everyone has this problem and the same symptoms....what I don't understand is why it doesn't throw a CEL if its malfunctioning!

 

[r1991_4g63t]

I guess its worth a shot. Wouldn't hurt anything to replace the sensor. If its not it, then at least I know its not gonna go bad for a while!

It seems like everyone has this problem and the same symptoms....what I don't understand is why it doesn't throw a CEL if its malfunctioning!

on the 1g cars there are very few things that will throw a code, and unfortunaly that the Coolant sensor isnt one of them.

 

[Raptoreborn]

I guess its worth a shot. Wouldn't hurt anything to replace the sensor. If its not it, then at least I know its not gonna go bad for a while!

It seems like everyone has this problem and the same symptoms....what I don't understand is why it doesn't throw a CEL if its malfunctioning!

Give it a go for sure. When mine went bad it was like continously below 30c everytime I would not get a cel. Sure enough after 2 days of my car being dead in the snow, swaped
out the temp sensor and it fired right up w/ perfect idle.

 

[tsi1991awd]

I just called Napa and they had one in stock for $27.38 and I asked if there was a cheaper one and he said he could get one in by around noon, which cost $19.97....so after I get off of work ill go pick it up.

I'm thinking it might be that sensor, now that I think of it. Because after its started, it will idle at 2,000 and then drop down to a bit less than 1,500 then back up to 2,000 then back down. Sometimes it'll stop on its own and sometimes when I hit the gas, it'll stop. Not sure if the sensor would cause this or not, but that does happen....not all the time, but sometimes.

 

[r1991_4g63t]

I just called Napa and they had one in stock for $27.38 and I asked if there was a cheaper one and he said he could get one in by around noon, which cost $19.97....so after I get off of work ill go pick it up.

I'm thinking it might be that sensor, now that I think of it. Because after its started, it will idle at 2,000 and then drop down to a bit less than 1,500 then back up to 2,000 then back down. Sometimes it'll stop on its own and sometimes when I hit the gas, it'll stop. Not sure if the sensor would cause this or not, but that does happen....not all the time, but sometimes.

the sensor can cause this because especially if its reading colder than it really is ### the computer is trying to give it more fuel to warm it up

 

[tsi1991awd]

the sensor can cause this because especially if its reading colder than it really is ### the computer is trying to give it more fuel to warm it up

Ill see what's up with it. Hopefully the sensor is the problem and nothing else. When the car warms up though, is the sensor still reading wrong?

 

[r1991_4g63t]

it just depends on the sensor really, with mine it was reading extremely hot all the time. its also possible if its reading cold at startup it could be reading cold when warm also which will make it run rich as the ecu is trying to war the car up. kinda the same reason you dont wanna put a colder t-stat in, the ecu needs the motor to be a certain temp to run right.

 

[tsi1991awd]

I called Schucks and they had 2 sensors...one the guy said had a gauge...I didn't know wtf that was. It popped up when he looked for the Talon TSI so I don't think its a temp gauge...I told him coolant temp sensor so idk. But I'm still getting the one from Napa...better deal.

Also when I did my radiator, I changed the thermostat as well. The guy I bought it from said he changed it but when I took it out, it was a 180* thermostat. I put in a 195* and its actually running a bit cooler than it was when I first got the car. It could be because I flushed the whole cooling system and put a bigger aluminum radiator in.

 

[r1991_4g63t]

I called Schucks and they had 2 sensors...one the guy said had a gauge...I didn't know wtf that was. It popped up when he looked for the Talon TSI so I don't think its a temp gauge...I told him coolant temp sensor so idk. But I'm still getting the one from Napa...better deal.

Also when I did my radiator, I changed the thermostat as well. The guy I bought it from said he changed it but when I took it out, it was a 180* thermostat. I put in a 195* and its actually running a bit cooler than it was when I first got the car. It could be because I flushed the whole cooling system and put a bigger aluminum radiator in.

there are two sensors, one has 1 wire thats for the guage, the other has 2 its for the ecu, you need the one with 2 wires

 

[tsi1991awd]

there are two sensors, one has 1 wire thats for the guage, the other has 2 its for the ecu, you need the one with 2 wires

Hmmm, maybe the price I got from Napa was for that gauge sensor for $19.97 and the $27 one was for the sensor I need. I have no idea. I guess ill find out when I get there. They have the $27 one in stock and the other was being ordered and will be there at noon. Soooo, maybe I'm going to have to spend a little more than I thought.

Hopefully that fixes the problem then.

 

[r1991_4g63t]

did you test the old one? if you have other transportation take it out and take it in with you and see if they have a multimeter and have them test it against the new one. all you do is put the 2 leads from the tester on the 2 prongs of the sensor and see how much resistance it reads. with it out of the car it should be pretty close to the same temp as the new one so they should be pretty close in resistance.

 

[tsi1991awd]

I took my car to work, sensor is still in...and I didn't have time to check the ohm resistance this morning before work. I might be able to take it out later tonight and then go up to Napa tomorrow morning since I'm off of work and check. Although this is most likely the cause, it would save me money not buying a part I didn't need.

Can you tell me what the ohm resistance is supposed to be when the engine is cold? That way I can check it later and be sure...

 

[r1991_4g63t]

I took my car to work, sensor is still in...and I didn't have time to check the ohm resistance this morning before work. I might be able to take it out later tonight and then go up to Napa tomorrow morning since I'm off of work and check. Although this is most likely the cause, it would save me money not buying a part I didn't need.

Can you tell me what the ohm resistance is supposed to be when the engine is cold? That way I can check it later and be sure...

ive been looking through different things trying to find the chart, i had originally gotten the data from mitchell when i worked at the last shop i was at. it showed what the resistance was supposed to be at all different temps. thats how i knew my car was thinking it was 240*+ when it was really around -20* the higher the resistance the colder. the warmer it gets the lower the number.

 

[r1991_4g63t]

water temps of 32* 5.1 - 6.5k ohms
" " " 68* 2.1 - 2.7k ohms
" " " 104* .9 - 1.3k ohms
" " " 174* .26 - .36k ohms

there ya go, was looking in the wrong spot

 

[tsi1991awd]

Thanks, ill check and see what it says. Maybe ill get a cup of ice water and put the sensor in it and see what it reads. It should read some crazy high resistance if its bad, am I correct?

 

[r1991_4g63t]

Thanks, ill check and see what it says. Maybe ill get a cup of ice water and put the sensor in it and see what it reads. It should read some crazy high resistance if its bad, am I correct?

wrong, in cold water it SHOULD read higher, then the warmer the water the lower the resistance

 

[tsi1991awd]

wrong, in cold water it SHOULD read higher, then the warmer the water the lower the resistance

So what everyone is talking about i s when the sensor takes a crap, say on a 32 degree morning instead of reading 5.1k ohms like it should, it'll read say 174 degrees (.26k ohms)

OR is the sensor reading a lot colder than its supposed to on a 32 degree morning? Say, its supposed to read 5.1k ohms but its reading -100 degrees or something?

 

[r1991_4g63t]

mine was reading like.02k ohms, so really ####ing hot, when it was below 0 outside