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 Inläggsrubrik: Missfire with standalone
InläggPostat: sön aug 12, 2018 5:17 pm 
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Blev medlem: sön jan 05, 2014 8:54 am
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Hi guys,sorry for writing in english,my swedish is not to god to explain this.
I have small random misfire on idle,only when car starts to be worm,so nothing when cold.
The car has Maxxecu together with Audi red ignition coils,and flex sensor for ethanol.
What i noticed is that when i turn on high beams(helljus) or cooling fans kick in,missfire dissapears completely.
I thought that generator is creating some electrical noise and i change it but problem remains.
Did anyone had problem like this,or if someone knows what can be the problem?

Thanks a lot in advance


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InläggPostat: mån aug 13, 2018 7:03 am 
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Blev medlem: ons okt 22, 2003 10:25 pm
Inlägg: 9788
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What fuel injectors do you have?
I'm guessing you have lambda 1.0 as your target at idle, what happens if you change your target lambda down to 0.90-0.95?

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InläggPostat: mån aug 13, 2018 8:28 am 
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Blev medlem: sön jan 05, 2014 8:54 am
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Injectors are high ohm Siemens Dek 870 ccm.
Lambda target is 1.
I can try changing it so we see what happens.
Is it possible that spark plugs that j have are not working well with this audi ignition coils ? What plugs should i use with them?


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InläggPostat: mån aug 13, 2018 3:45 pm 
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Blev medlem: ons okt 22, 2003 10:25 pm
Inlägg: 9788
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A high power turbo engine can require a quite small spark plug gap of 0.40-0.50 mm which can have a detrimental effect on idle quality. Also changing spark plugs once every season is usually a requirement with cold plugs if you run them a lot in a daily driven summer car. What spark plugs do you have?

If you are very picky about idle quality you should be aware that it requires _everything_ to be in order, especially with large injectors. I'm quite sure that if you let it idle a bit richer the issues will go away. This is mainly caused by small differences in fuel injectors (low pulsewidth), cylinder sealing (rings, valves) and lots of other things (not only software). Even with a lambda reading of 1.0 you can have one cylinder running richer than 1.0, and another running leaner with a mis-fire now and then.

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Mattias Sandgren
Säljer, installerar, mappar och justerar motor-styrsystem och tillbehör. Link, MaxxECU, ECU Master, VEMS, m.fl.
Egen nav-dyno och motor-bänk i Sävar.
Säljer, flödestestar och tvättar bränsle-spridare.
Bild
Skicka mail, PM eller ring vid intresse. Innehar F-skatt. Jobbar mest i norr.


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InläggPostat: mån aug 13, 2018 4:47 pm 
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Blev medlem: sön okt 26, 2014 6:25 pm
Inlägg: 1471
I once experienced similar problems with Megasquirt. Solution was less voltage correction and richer idle.

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InläggPostat: tis aug 14, 2018 11:39 am 
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Blev medlem: tis nov 11, 2003 1:23 am
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bojke skrev:
I have small random misfire on idle,only when car starts to be worm,so nothing when cold.

What i noticed is that when i turn on high beams(helljus) or cooling fans kick in,missfire dissapears completely.

How is the fuel compensation against engine temp?
Do you have misfire when the engine is really hot?

What does the log on the battery voltage indicate when turning on the main beam
or the cooling fan is running

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InläggPostat: tis aug 14, 2018 4:19 pm 
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Blev medlem: sön jan 05, 2014 8:54 am
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I am using NGK BCR8ES spark plugs with gap 0.5 mm,and they are new.
The engine is 5 cylinder turbo Fiat with GTX3076 turbo.I already checked vakum leaks,ignition coils,spark plugs etc,even compression.
Everything seams to be ok.
The car worked good without missfire with original ECU.Then i switched to Maxxecu Race and after a while i noticed that small missfire.
I tried 2 sets of injectors also,without change,still same.
I am total beginer regarding standalone,which means,i do not know what voltage correction to change,or what to do,unfortunatelly.
I wonder if its possible that someone can check it thru Team viever or something similar


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InläggPostat: tis aug 14, 2018 4:39 pm 
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Blev medlem: tis nov 11, 2003 1:23 am
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Can you mail over a map and I can look at it
is something strange.

super7@hakmark.net


//Nisse

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InläggPostat: tis aug 14, 2018 5:50 pm 
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Blev medlem: sön jan 05, 2014 8:54 am
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I can do that tomorrow because the car is in a distant garage.


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InläggPostat: fre aug 17, 2018 8:41 pm 
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Blev medlem: sön jan 05, 2014 8:54 am
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I can only say that i tried to change lambda from 1.0 to 0.9 at idle and then it worked.The engine was working without missfire.
What is actual problem here and why it needs richer idle,or can it be fixed so i do not have problems on besikt with rich idle or gasses


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InläggPostat: lör aug 18, 2018 10:59 am 
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Blev medlem: sön okt 26, 2014 6:25 pm
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As already told, there may be differences in each cylinders lambda-value even if the total sum is 1. You "need" sekvential injection to correct that. Try lamda target 0,97 or something like that, ethanol, hotter plugs with smaller gaps, and or smaller injectors.

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InläggPostat: lör aug 18, 2018 8:35 pm 
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Blev medlem: sön jan 05, 2014 8:54 am
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Regarding injectors,i already had Siemens Deka 630. But they were acting absolutely same way.
So you are actually saying that if i install egt sensors on every cylinder i can use that to correct cylinder mixture separately and fix problem.


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InläggPostat: lör aug 18, 2018 10:38 pm 
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Blev medlem: sön okt 26, 2014 6:25 pm
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No. Even if the injectors are mached, difference may occure to uneven cylinder wear.

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InläggPostat: sön aug 19, 2018 4:16 pm 
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Blev medlem: sön jan 05, 2014 8:54 am
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I checked compression and its same on all 5 cylinders,also engine works normal with original ECU.
So i doubt its engine wear,but only some kind of adjustment.


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InläggPostat: sön aug 19, 2018 5:42 pm 
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Blev medlem: sön okt 26, 2014 6:25 pm
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I mean, the cylinders work under slightly different circumstances (wear, flow in and out, carbon build up, etc.) And therefor it may be hard to get the engine idle at a total lambda of 1, especially with big injectors.

Although I had the same problem, I did pass the exhaust test and even with a bad cat. The trick was very much retarded ignition (almost 0) and E85 and lambda target very close to 1.

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