VW 2.0TDI SPECIALIST

[costyrzv]

Hi, I have a 2007 a4 b7 with a rebuilt engine, so it goes like this , first start, engine started runned like a dream until it reched 90° , when engine was up to temp the engine started to act up, sloppy idle and wouldn't rev up anymore, stopped the engine, car didn't start again . Now somebody heated the ecu , plugged it back in, car ran fine until it reached 90° again and the same issues, not revving, sloppy idle, after stop , no start . After this , new ecu immo off , car won't start at all . Edc16u31 ori file with immo off and 2.0tdi BRE or BLB .
Anybody has any idea why it would only start after heating the ecu ? And not starting eith the new one ? No codes on VCDS .

[Mario6]

Hi, I have a 2007 a4 b7 with a rebuilt engine, so it goes like this , first start, engine started runned like a dream until it reched 90° , when engine was up to temp the engine started to act up, sloppy idle and wouldn't rev up anymore, stopped the engine, car didn't start again . Now somebody heated the ecu , plugged it back in, car ran fine until it reached 90° again and the same issues, not revving, sloppy idle, after stop , no start . After this , new ecu immo off , car won't start at all . Edc16u31 ori file with immo off and 2.0tdi BRE or BLB .
Anybody has any idea why it would only start after heating the ecu ? And not starting eith the new one ? No codes on VCDS .

If you have VCD$ or Delphi/Autocom, check the blocks of measured values 13 and 23, maybe the injectors do not work properly after the engine warms up. You can also remove the plug from the coolant temperature sensor when the engine is heated to 90 * C and try to start it.
Does the engine start normally when cold?

[costyrzv]

If you have VCD$ or Delphi/Autocom, check the blocks of measured values 13 and 23, maybe the injectors do not work properly after the engine warms up. You can also remove the plug from the coolant temperature sensor when the engine is heated to 90 * C and try to start it.
Does the engine start normally when cold?

Engine starts and runs normally when ecu is heated up with heatgun, but when reaching 90° does not rev up or anything, if ecu is not heated up car does not start, hot or cold, water temp sensor removed and car does not start either , will remove glowplugs to see if injectors are fiering and will check injector blocks, but it's just too weird what is happening with this, I got vcds and ODIS aswell .

[costyrzv]

Removing the water temp sensor does not help

[Mario6]

Removing the water temp sensor does not help

Replacing the ECU with IMMO disabled also did not help?

[costyrzv]

Replacing the ECU with IMMO disabled also did not help?
No , no change, car won't start . I'll try and hook up diagnostic tool today and see if something comes up now, will also try to remove the camshaft position sensor.

Thank you all for help , other suggestions ?

[johnnybeast]

Hey,

Need to check live data on all the temperature sensors, there's 2 coolant ones (engine and radiator), air intake temp, fuel temp, and an ambient temp sensor inside the ECU. There are other ones, but they won't effect the running/starting of the engine.

What work has been done to the engine, you say rebuilt, but to what extent? Was it removed

J.

[costyrzv]

Hey,

Need to check live data on all the temperature sensors, there's 2 coolant ones (engine and radiator), air intake temp, fuel temp, and an ambient temp sensor inside the ECU. There are other ones, but they won't effect the running/starting of the engine.

What work has been done to the engine, you say rebuilt, but to what extent? Was it removed

J.
Removed, engine came stripped, put everything back on it from the old engine, old engine was siezed , timing and everything done correctly, car just spins, no start no codes , will check every temp sensor .

[costyrzv]

SOLVED !!
So the thing with these a4 b7 tdi , if you have the fuse inside the car good it will connect to diagnostic tool , but won't throw any codes and car won't start, nou i removed that fuse and had same results as earlier, like there was no change so I thought the ecu was not getting any power , went and there is another fusebox/relaybox inside the ecu box, fuses good, but I was suspecting the small black relay, wich was the main relay , now after removing the relay it looked dodgy , so put a new one in , car started right away !

[costyrzv]

940525

The small black one on the left, thanks to all of you for help, let'keep this comunity together!! 👍👍

[costyrzv]

940525

The small black one on the left, thanks to all of you for help, let'keep this comunity together!! 

UPDATE: Car was not running right when getting to 90° C , engine wobbly, gas pedal not responding, after stop, no start, so the reason that relay was fried it's because someone forgot to tighten the ground cable , in this a4 b7 in the engine bay area following the main ecu wiring harness you will find a broun cable that goes on the chasis with a 10mm nut, make sure it's tight and it's making good contact, old ecu was fried, relay was fried.
Have a good one everyone !!