NefMoto

Hi

Problem description:
After deleting the DTC / resetting learned values, the idling speed remains at 800 rpm for a certain time. The idling speed (nmot) then starts to rise to 920 rpm. The target idling speed (nsol) also increases to 870 rpm.

From this point on, it is difficult to increase the engine speed to 1400 rpm with the accelerator pedal when the vehicle is stationary. At first, the engine does not respond to the accelerator pedal and then starts to fluctuate between 1200 rpm and 1600 rpm.

These problems occur when the air conditioning is switched off. When the air conditioning is switched on, the idling speed remains at 800 rpm. In addition, the engine speed can easily be increased and held at 1400 rpm with the accelerator pedal when the vehicle is stationary.


Baseline: S4 B5 D-Box
- MAF OEM
- Throttle valve OEM
- Thicker cylinder-head gasket
- Larger fuel injectors
- Larger turbochargers
- KFMIRL --> up to and including 60% relative torque unchanged.
- KFMIOP --> up to and including 50.251% cylinder filling unchanged.
- KFZWOP --> up to and including 50.251% cylinder charge unchanged.
- KFZWOP2 --> up to and including 50.251% cylinder filling unchanged.
- KFZW --> up to and including 50.251% cylinder filling unchanged.
- KFZW2 --> up to and including 50.251% cylinder charge unchanged.
- WDKUGDN --> up to and including 760 rpm unchanged.



Analysis:
First spark advance is decreasing before throttle plate angle is increasing.


After engine start (timestamp 9 sec.) up to timestamp 37 sec.
----------------------------------------------------------------------

• Ignition angle --> 2.25 - 11.25 BTDC
• EngineLoadRequested (rlsol_w) --> 12%
• EngineLoadRequested (rl_w) --> 10.2% - 10.8%
• fkmsdks_w --> 0.843751

Timestamp 37 sec. up to timestamp 57 sec.
-------------------------------------------------

• Ignition angle --> Spark Advance is decreasing
• EngineLoadRequested (rlsol_w) --> 12%
• EngineLoadRequested (rl_w) --> 10.7% - 11.2%
• fkmsdks_w --> 0.843751

Timestamp 57 sec. up to timestamp 69 sec.
-------------------------------------------------

• Ignition angle --> Constantly 2.25 BTDC
• EngineLoadRequested (rlsol_w) --> 12%
• EngineLoadRequested (rl_w) --> 10.7% - 11.2%
• fkmsdks_w --> 0.843751

Timestamp 57 sec. up to logfile end (timestamp 88 sec.)
---------------------------------------------------------------

• Ignition angle --> 1.5 - 2.25 BTDC
• EngineLoadRequested (rlsol_w) --> 12%
• EngineLoadRequested (rl_w) --> 11.2% - 12.4%
• fkmsdks_w --> 0.843751

Questions:
Why does the ME7 behave like this? Is it because the engine control unit is trying to match rl_w to rlsol_w?

When the air conditioner is on, the idling speed remains at 800 rpm. In addition, the engine speed can easily be increased and held at 1400 rpm with the accelerator pedal when the vehicle is stationary.

At timestamp 5,750 sec.
---------------------------
--> The air conditioning compressor is switched on


Between timestamp 22.27 sec. and timestamp 49.712 sec.
------------------------------------------------------------------
--> idling increase with accelerator pedal --> the engine speed can be easily controlled with the accelerator pedal.


Between timestamp 49.712 sec. to end of log file (timestamp 57.901 sec.)
----------------------------------------------------------------------------------
--> idling with air conditioner on

If its your own car revert latest change back to stock
If the car came with this problem flash stock file with changed injectors and log again.

Any reverse flow in the maf? Is air intake stock?

Thanks for your time.

air-filter housing --> stock
air-filter --> stock
maf --> stock
throttle body --> stock
intake camshaft --> from 2.8L naturally aspirated engine
cylinder bore diameter --> 82.0mm instead of 81.5mm
Thicker cylinder-head gasket


What exactly do you mean by that? Apart from the possibility that the air flow is pulsating, I am not aware of any backflow.


I have made several dozen adjustments to the software. But only now I became aware of the problem with the idling speed, because the vehicle has been idling for a longer time with the air conditioner off.

I hope that someone in the forum can tell me why the engine control unit is behaving like this. There must be a reason why first the Spark Advance is decreasing and then the Ignition angle stays at 1.5 - 2.25 BTDC. It seems to me that the engine control unit wants to build up a torque reserve.

If nobody can explain this behavior of the engine control unit to me, I will try to find out with which adjustment step I caused the strange behavior by undoing my adjustment steps step by step.

Update:

OK. I went back to the D-Box 8D0907551D 0261206382 350243, downloaded from this forum (http://nefariousmotorsports.com/forum/index.php?topic=1494.0) and changed the following areas (see Tune 88 in the attachment):

• - KRKTE
• - TEMIN
• - TVUB
• - FKKVS

The problem persists even with Tune 88.

After flashing Tune 88, disconnecting the battery and reconnecting the battery, I created the log file "Idle after disconnecting battery.csv":

- From engine start to timestamp 86, the value of nsol (RequestedEngineIdlingSpeed) = 800 rpm.

- Between timestamp 86 and timestamp 107, I gave several throttle strokes to check how well the idle settles again. The value of nsol remains at 800 rpm.

- From timestamp 113, the engine control unit starts to change the value for nsol continuously. As a result, the idling speed of the engine begins to oscillate.

- From timestamp 131, I switched on the air conditioning control unit and the air conditioning compressor. The value goes from nsol = 800 rpm. The engine then runs constantly at 800 rpm.

- From timestamp 176, I switched off the air conditioning control unit and the air conditioning compressor again. The value of nsol increases again. The engine control unit changes the value for nsol constantly. As a result, the idling speed of the engine starts to oscillate.

- From timestamp 220, I switched on the air conditioning control unit and the air conditioning compressor. The value of nsol = 800 rpm. The engine then runs constantly at 800 rpm.

- From timestamp 227, I only switched off the air conditioning compressor (ECO button on). The value of nsol increases again. The engine control unit changes the value for nsol constantly. As a result, the idling speed of the engine starts to oscillate.

- From timestamp 231, I have switched on the air conditioning compressor (ECO button off). The value of nsol = 800 rpm. The engine then runs constantly at 800 rpm.

So open the FR and log all the variables that go into nsol.

To be able to exclude a hardware malfunction of the ecu as cause, I took a second D-Box ecu, flashed the same tune and tested it again. The same problem also occurs with the second D-Box ecu.

Hi prj

Thanks for your advice. I'll try to apply it and get back to you.

Hello everyone

Problem solved. The vacuum hose between the intake manifold and the brake booster had a small crack.

After replacing the vacuum hose with a new one, the problem no longer occurs.