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Topic
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I recently bought an Audi A4 with the 1.8T. Has had a cranking no start since I purchased it. I was told that it broke a serpentine belt cause the AC locked up. The previous own had the AC removed and a new belt installed however a P0011 was thrown and then cleared.
Since I purchased I have:
– Replaced Cam Sensor
– Replaced Crank Sensor
– Replaced both ECM Relays
– Cleaned Battery Terminals
– Cleaned ALL Grounds
– Replaced all plugs
– Checked ALL fuses
– Checked Compression
– Checked Timing
– Checked Fuel pressure
– Disconnected battery for 5 minutes
– Unplugged and replugged in every sensor.
– Pulled codes (Recently got P0685)I’ve officially ran out of ideas.
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Replies
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It is either going to be no fuel, no air, or no spark. Looks like you covered your bases with the electrical components. I would only look for disconnected harness going to the plugs and things like that though for all of them to fail to where you have no start is unlikely. Check your fuel pump fuses, then relays, then check for clogged fuel filter or clogged injectors. In that order as the others are not as likely to give you this big of issues. If it throws codes, I would look at those systems first as it could be a bad sensor that is disabling your engine from starting. Sometimes one harness being disconnected can give you many other codes that are not even related so make sure everything is connected. I have seen on some ford vehicles where a mass airflow sensor was disconnected and it gave a code for crankshaft position sensor. Just a good idea to check everything….
I have fuel just no spark I have checked the harness all the way back to the ECU it looked good. The no spark issue is what prompted me to change crank and cam sensor. I did noticed that when cranking there is no output by the MAF sensor however the MAP sensor is working.
The only thought I have right now is ECU as I was told jumper cables were hooked up backwards once. However I dont understand why I would have injectors and not Spark if it was the ECU
Time to look at a schematic. May have to check wiring going back to the ECU. My guess based upon your description would be something in the harness, or possibly something with a security system, if so equipped.
Also, the reason you may have fuel and no spark is that on many modern cars (not sure about Audi) is that the crank position sensor signal turns on the fuel pump and the Cam position sensor signal allows the spark. May start at the Cam position sensor and work back…
Good luck,
Karl
I noticed the throttle body is completely silent until I manually jump 12volts to the coils when I jump 12volts to the coil the throtle body buzzes and responds to input. without the 12volt jump to the coils the throttle body is silent and dosent respond to input. The fuel pump is also alot loaded when coils are jumped pin 1 to 12 volts
Is there a unit that disables the car if the chip from the key is not present on the car? check the chip on the key and check the killing unit see if there is an issue there. That is what it sounds like to me if it has one. I cant think of another reason it would fail honestly. You may have to bite the bullet and take it to a dealer or try deciphering a wiring diagram and see where you may be losing connections or what it could possibly be.
the US Audi’s of this year do not have an immobilizer. If it did and it was the Audi immobilizer allows to engine to run for about 5 seconds and then kills it and puts a Yellow Key icon on the dash.
I am gonna try replacing the under hood loom as the wire coatings are kinda crispy. Might be grounding somewhere.
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