Engine starting problem
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AudiWorld Junior Member
Joined: May 2021
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Engine starting problem
2004 2.7 TT with 101,000 miles, six speed manual. First I had a problem where it would take 10 or so tries to get the engine started, gradually increasing its firing until it started. My mechanic solved it by changing the temperature sensor, which was reading hot and not allowing proper fuel mixture. Then I drove it for a week or so including a 250 mile trip to Vermont, during which it ran beautifully. Parked it overnight and in the morning it would not start no matter how many times I tried. Had to get it towed and wait a week for an appointment with a rural mechanic. He said the spark plugs were fouled and he pulled a low temperature code from the engine. it started up fine and ran 50 miles, no stumbling or misfiring. When I tried to start it the next morning, tow truck all over again. In Williamstown Massachusetts, mechanic backlog is two weeks! I have no clue why it has the starting issue. It seems very different than the first time with the temperature sensor: no firing at all. I suspect the spark plugs were not the issue but something else. Anyone have a clue please?
AudiWorld Senior Member
Joined: Feb 2018
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From: Canada
Crank but no start along with not firing at all could be fuel related. Is the electric fuel pump spinning inside the tank? Can remove connector and check the fuel pump motor windings resistance with an ohm meter - should be around 5 to 10 ohms. Usually when pump motor winding starts to fail it will read high like 50 ohms or more.
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AudiWorld Junior Member
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Unlikely because the fuel pump was changed three months ago.
Someone who is not an Audi person said it might be a sensor such as crankshaft sensor. Since the car is not running yet while cranking, it does not send a code that it is failing?
Someone who is not an Audi person said it might be a sensor such as crankshaft sensor. Since the car is not running yet while cranking, it does not send a code that it is failing?
AudiWorld Senior Member
Joined: Feb 2018
Posts: 1,937
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From: Canada
Three most common causes of crank-no-start for this era Audi engines are:
Fuel Pump
Fuel Pump Relay
Crank Position Sensor
Hot engine crank-no-start is often a failing G2/G62 Coolant Temp Sensor
Fuel Pump
Fuel Pump Relay
Crank Position Sensor
Hot engine crank-no-start is often a failing G2/G62 Coolant Temp Sensor
Thread Starter
AudiWorld Junior Member
Joined: May 2021
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Thanks! I believe it's the CPS, because a) it would not start when cold and b) all the other causes mentioned were from components recently replaced, including the coolant temperature sensor.
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