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TheEugeneKam
11-06-2010, 08:06 AM
Well here is my story. My Audi will not start sometimes, its turning but not getting to start, when it does the rpm needle slowly climbs to idle. At times i have to crank it a few times, even when i hold it for like 10 seconds it still wont start. I noticed last night that it might only happen when the car is warm, if i stop it and start up 5 min later. Sometimes it start normally without any issues. Before it used to happen once every few weeks or so, now yesterday it happened 3 times in arrow and stopped after. My idle seems to be fine, as for the sound its a little weird but i didn't really notice how it sounded before.
Here is the thing my CEL goes on and off after a few hours, i checked it and every time its the coolant temp censor, but as far as i know it shouldn't cause this issue, should it?? Any help on this matter?

bofa deez
11-06-2010, 09:08 AM
sounds a bit to me like a fuel pump issue. if your loosing residual fuel pressure when you turn off the car, it will take a few seconds to prime and fill the lines again with fuel the next time you start your car.

TheEugeneKam
11-06-2010, 09:56 AM
hmmm interesting I though it might be my fuel pump, last time i had that though my car wouldn't even start, and having this periodically, im not sure. On top of that it works perfectly after, in my experience fuel pump usually will give you issues even when driving.

walky_talky20
11-06-2010, 08:54 PM
Coolant temp sensor can *absolutely* cause this issue. I've seen it happen many times. Sometimes the sensor reads so high (hot) that a cold start is nearly impossible. That happened to my car. Left it sit for 2 days, went to start and it acted like it wasn't getting fuel. Cranking for a long time while pumping the throttle and sputtered just a bit. Pulled up vag-com and the coolant temp reading was pegged hot (160C or something, way hot), with outside temp of like 10C. Popped in a new sensor and it started right up.

The problem is the sensor reads hot, when the coolant is actually cold. This prevents the cold start procedure, and you get no cold start enrichment (aka: choke), leading to a lousy or impossible cold start situation.

Also, whenever troubleshooting issues like this, you want to fix your *known* problems first. Especially when they are less than $20. In other words, don't go pricing fuel pumps until you replace this cheap sensor that you *know* is bad.

TheEugeneKam
11-09-2010, 08:31 AM
Thank you very much, that clarifies things a lot! It makes perfects sense. Im gonna go get that fixed as soon as i am done class. Appreciated :D

mmmjboner
11-09-2010, 09:06 PM
Absolutely sounds like a CTS. See my thread:

http://www.audizine.com/forum/showthread.php/128754-Hot-start-issue-00-A6-2.8L?p=1593039

prizmatik
11-09-2010, 09:45 PM
Bump.

Mr.Black
11-10-2010, 05:07 PM
Coolant temp sensor can *absolutely* cause this issue. I've seen it happen many times. Sometimes the sensor reads so high (hot) that a cold start is nearly impossible. That happened to my car. Left it sit for 2 days, went to start and it acted like it wasn't getting fuel. Cranking for a long time while pumping the throttle and sputtered just a bit. Pulled up vag-com and the coolant temp reading was pegged hot (160C or something, way hot), with outside temp of like 10C. Popped in a new sensor and it started right up.

The problem is the sensor reads hot, when the coolant is actually cold. This prevents the cold start procedure, and you get no cold start enrichment (aka: choke), leading to a lousy or impossible cold start situation.

Also, whenever troubleshooting issues like this, you want to fix your *known* problems first. Especially when they are less than $20. In other words, don't go pricing fuel pumps until you replace this cheap sensor that you *know* is bad.

Ding, Ding - In my past experience this was the prob - exactly.

walky_talky20
11-10-2010, 08:33 PM
Ding, Ding - In my past experience this was the prob - exactly.

This is the more common failure. mmmj had the other failure, where it reads cold all the time, creating a hot start problem. In reality this thing has like 6 different failure modes. It is a piece of junk. I wonder why it's such a problem. I don't think I've ever heard of someone changing a CTS on a Toyota Camry...ever.

TheEugeneKam
11-11-2010, 07:54 AM
Well i changed mine it was like 35$ here in Canada. Interestingly enough... there was a 2006 ish pasat , and a 2001 generation jetta...getting the exactly same thing done. Seems to be pretty common lol