AUDI A4 ALZ PROBLEM

[pandelis]

Hello friends i have a audi a4 2002 alz engine in my garage, sometimes don't start and hear popping in the air filter housing
and sometimes starting well. no fault codes
check the timing is ok i replace MAF , CRANKSHAFT SENSOR , CAMSHAFT SENSOR , TEMPERATURE SENSOR , IGNITION COIL , IGNITION CABLES ,
check the oxygen sensor with a simulator , check the camshaft , the compression ,egr, the gear of crankshaft with a mirror,manifold for leaks,
check the signals with oscilloscope in the ecu, and i dont remember what else .

any idea for this problem.

sorry for my english.

[rideon]

Fuel pressure?...............

[pandelis]

yes i have cheked it.it's ok

[doktorabg]

yes i have cheked it.it's ok

When is 100% ok than you have any mechanical problem.
Check valves, camshaft, injectors, cat.

[autoden]

sticky valves or wrong oil jacking up the lifters, and a lot of time and money spent on parts it don,t need. Hope your customer isn,t going to pay for all this!
autoden

[pandelis]

When is 100% ok than you have any mechanical problem.
Check valves, camshaft, injectors, cat.

i have checked camshaft , injectors , and cat not the valves but i have checked the compression

[pandelis]

sticky valves or wrong oil jacking up the lifters, and a lot of time and money spent on parts it don,t need. Hope your customer isn,t going to pay for all this!
autoden

not the customer will not pay for all that autoden. If the problem is in the valves would have good compression 13 bar ?

[pandokrator]

first of all , remove fuel pump rellay,
with diagnostic live data go to crank rpm option,
crank engine and see if the rpm from live data matching
with the dashboard's rpm.
most times this symptoms comes from deffective crank sensor,bad rellay
or pure wire contact.
bR

[pandelis]

first of all , remove fuel pump rellay,
with diagnostic live data go to crank rpm option,
crank engine and see if the rpm from live data matching
with the dashboard's rpm.
most times this symptoms comes from deffective crank sensor,bad rellay
or pure wire contact.
bR

pandokrator as said i have checked the rpm from live data and matching with dashboard's rpm.
I have checked the relay with a lamp at 87 and it's ok
Crankshaft sensor has been changed and check the signal on the unit.

[pandokrator]

i have read carefully your post my friend,
that i say is check with live data when the start problem appear.
and of course try identify the cause when the problem appear ,,
..eg loose spark,loose injectors ?
that will lead faster in the real problem and solution of this.
also check when car not start if your central rellay is on or off.
many loom of this cars have factory problem on one ground behind the column of the driver's side.
bR

oh,and Never don't trust "lamp test" ;-)

[pandelis]

pandokrator sorry i meant as you told me i have checked the rpm from live data and matching with dashboard's rpm.
the relay checked when the problem appear.
i will check the ground.

[pandelis]

and the ground is ok . I gave ground from the battery and the problem still exists.

[alessioblaupunkt]

Procedure from doNotTrust 'RongAutodata?:
No fault code ---> Do you have strong blue spark at spark plug?

Answer this then we could go 1 step further. Or back.

[pandelis]

Procedure from doNotTrust 'RongAutodata™:
No fault code ---> Do you have strong blue spark at spark plug?

Answer this then we could go 1 step further. Or back.

yes i have

[doktorabg]

How many times the car can't start in the day?
Always is the same or not.
What is lamda value and maf and all important sensors when don't start and you hear popping in the air filter?
Which tool for diagnostic do you use?

[alessioblaupunkt]

Now we assume the High Voltage leads are fitted.
It's time to check fuel pressure. Take a look at the picture.
269719
These are generic value.



Tomorrow I'll give you the schematic so you could check if the crankshaft sensor is supplied when the car doesn't start.


I think Lambda and MAF are not strictly necessary to start the engine.
You could disconnect them (they could be shorted).

[pandelis]

How many times the car can't start in the day?
Always is the same or not.
What is lamda value and maf and all important sensors when don't start and you hear popping in the air filter?
Which tool for diagnostic do you use?

When it's cold usually start well, when the temperature is 90 degree it doesn't start one or two maybe and five times and then start o.k.
if started well it working well and on the road.
i use carman and texa
this time i don't remember the value from lamda and maf but i use a simulator for the lamda and i was sent different values to ecu and Nothing happened.


sorry for my english

[pandelis]

Now we assume the High Voltage leads are fitted.
It's time to check fuel pressure. Take a look at the picture.
269719
These are generic value.



Tomorrow I'll give you the schematic so you could check if the crankshaft sensor is supplied when the car doesn't start.


I think Lambda and MAF are not strictly necessary to start the engine.
You could disconnect them (they could be shorted).

The fuel presure is ok and it's not 3 bar without vacuum and 2,5 with vacuum but 4 and 3,5
maf and lamda i had disconnected and nothing happened

[alessioblaupunkt]

Alessio's™ hint:
If the engine is hot and doesn't start disconnect the coolant temperature sensor and see if the engine start.
If the sensor is bad the ECU told to the injector to deliver more fuel than necessary and the engine might not start.

Disconnecting the coolant temp sensor the ECU use the air temp and other info such as intake manifold pressure, rpm, etc.

'RongAutoData™ hint:
If the engine doesn't start:
Check for supply at the fuel injector terminal whilst cranking.
Is the supply voltage more than 9 Volts?


Answer this question and we will move one step further.


Forget the test at the crankshaft connector: you got rpm in the speedo so there all is fine.


Attached is the engine wiring diagram.

[doktorabg]

Alessio's? hint:
If the engine is hot and doesn't start disconnect the coolant temperature sensor and see if the engine start.
If the sensor is bad the ECU told to the injector to deliver more fuel than necessary and the engine might not start.

Disconnecting the coolant temp sensor the ECU use the air temp and other info such as intake manifold pressure, rpm, etc.

'RongAutoData? hint:
If the engine doesn't start:
Check for supply at the fuel injector terminal whilst cranking.
Is the supply voltage more than 9 Volts?


Answer this question and we will move one step further.


Forget the test at the crankshaft connector: you got rpm in the speedo so there all is fine.


Attached is the engine wiring diagram.

He said that the temperature sensor is new and is the same.
Crankshaft sensor can do the problem when hot is but must be stored error code for this
The car start but hard when warm is

[alessioblaupunkt]

:top: Ok let's see how many voltage he got in the injector when the engine doesn't start.

[pandelis]

The voltage in the injector is 11,7 when the engine does't start and the same when starting on the cranking
the maf signal is 1.3v at idle and the same when cranking.
The car is like have wrong firing order .
today i'am doing road test and the car haven't power until 3000rpm after 30 km i was have fault code 16555 system too lean bank 1

sorry for my english

[rideon]

............
Again ,fuel pressure,fuel injectors - removed and checked - one or more might be leaking or jammed,catalyst broken or burned...
Running out of ideas ....

[rideon]

The fuel presure is ok and it's not 3 bar without vacuum and 2,5 with vacuum but 4

If your pressure gauge is calibrated..... 4 bar seems to me a little too much ,that means that the fuel pressure regulator is not working quite right....

[alessioblaupunkt]

16555 = air leaks
With 16555 you'll fail the emission test because of high HC.
Take a look at these before putting your hands on the engine.
It's not the same engine but the concept is the same.
VW and AUDI Engine code P0171 P0174 P1136 and P1138 - YouTube (http://www.youtube.com/watch?v=NY0PZr_RWk8)

Smoke testing for codes P0171 P0174 - YouTube (http://www.youtube.com/watch?v=kZsqEfP-5zM)
For the rest:
11.7 volt is fine, also the 4 bar are ok, mine was a generic value.

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