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dx4picco

Idle control, VW IACV and frequency

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Hi,

a friend on mine is running an ATOM G4+ on his bmw M20 engine. He put  a VW ISCV from a vr6 (solenoid type, two poles on the plug, ref 0280140559), wired on aux2 output.

I can't get the idle tuned finely, the idle control vavle doesn't feels right.

How do you define a good control frequency of the ISCV? I've read ranges from 30Hz to 300Hz for different iscv. How should I proceed to find what frequency is the best for this one? I didn't find any data about these.

Thanks!

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I'm seeing a wierd behaviour that I have a hard time to explain.

After a cold start, post start enrichment does its job and decreases as supposed to. but then the car runs lean.

At one point it stalls by itself. I restart and then it runs to the lamda 0.9 it should for the 60+ ect in modelled mode.

How come such a difference with no changes? running lean at 1.2, then stall, restart and gives the awaited 0.9.

 

Someone to shed light on this?

Because of this I can't say yet if the 200hz made it better.

M20alphanV2.pclr Teste V2 départ froid.llg

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There are a couple of small differences I see but im not sure all of the lambda change is explained.

Before the stall your charge temp was 30°C, after restart it had increased to 41°, this would make about a 4% increase in fuel pulse width.  Also before the stall the engine was running in a VE cell of 50%, after restart the VE from the fuel table is 53.6%, so this is about a 7% increase in fuel.

Having said that, Im not sure I believe your lambda device as the injector duty cycle is actually quite a bit shorter after restart than before it stalled yet the lambda shows richer.  Inj DC dropped from 4% to about 2.5%.  What brand is the Lambda device and do you trust it?  Not many cars would actually idle at  1.2/1.3 lambda so it seems a little unbelievable.

 

Im not convinced your idle valve is working at all as in the first few minutes it goes from 70%DC to 30%DC with barely any change in idle speed.  Does it click when you set the output to test mode?

 

Now a questions:  

For the first 60 seconds the engine is revving up but the throttle shows zero.  Also at time 2:30 the engine starts revving but the throttle shows zero.  There must be some air coming from somewhere for the RPM to increase like this? 

 

Also, forgot to say, you should update your firmware, you are on a very old version that has had many improvements since.

 

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Thank you for your heads up.

My friend bought this ecu a while back got it tuned by someone who didn't know really link ecu and didn't run that great.

After I tuned my subaru on link and learnt the plateform, he asked me to retune his car.

I was not aware that his SW version was that old. I started back from scratch and used modelled fuel as well as tps based (was traditional + map, with his big cam and MAP directly on plenum, signal was pretty bad).

I'm trying slowing to get a hand on his engine.

The wideband is a Zeitronic, regular gauge + 0-5V signal. I would trust it and checked for exhaust leaks around the 02 sensor.

I was also surpised to see it run with such a high lambda, even more on this very sensitive engine. For the subject of the IACV, when I compare how crisp are the changes on my Ver4 subaru engine even 0.4% duty, and how not responsive is his IACV, I may tend more and more to think something is going on with it. I did not run a test mode as you mentioned. need to try that.

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So firmware updated.

Tested the ICV with aux2 and some noise did come out. I don't know in what extent that proves that it work, because I tried again afterwards to change de duty and the rpm din't really change.

What should be the wiring of such ICV? + on fixed 14V and - on Aux 2? or Aux2 on + and - to gound (if yes chassis ground? ecu ground?).

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12 hours ago, Adamw said:

For the first 60 seconds the engine is revving up but the throttle shows zero.  Also at time 2:30 the engine starts revving but the throttle shows zero.  There must be some air coming from somewhere for the RPM to increase like this? 

Idle igntion control made that.

it went over the 1600rpm threshold on its own and then went from the 14° idle to 20 something of main ignition map.

 

I made a cold start again and did get a good lambda curve this time. I did check for electrical gremlins but didn't find any bad contacts there.

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