Missfire with standalone

Insprutning, Tändsystem och Elektronik

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bojke
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Missfire with standalone

Inlägg av bojke »

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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mattias
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Re: Missfire with standalone

Inlägg av mattias »

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?
Mattias Säfsten (fd Sandgren)
Säljer, installerar, mappar och justerar motor-styrsystem och tillbehör.
Återförsäljare för MaxxECU, Link, ECU Master, VEMS, m.fl.
Nav-dyno och motor-bänk i Sävar vid E4.
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bojke
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Re: Missfire with standalone

Inlägg av bojke »

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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mattias
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Re: Missfire with standalone

Inlägg av mattias »

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.
Mattias Säfsten (fd Sandgren)
Säljer, installerar, mappar och justerar motor-styrsystem och tillbehör.
Återförsäljare för MaxxECU, Link, ECU Master, VEMS, m.fl.
Nav-dyno och motor-bänk i Sävar vid E4.
Säljer, flödestestar och tvättar bränsle-spridare.
Skicka mail, PM eller ring vid intresse. Innehar F-skatt. Jobbar mest i norr.
mauser240
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Re: Missfire with standalone

Inlägg av mauser240 »

I once experienced similar problems with Megasquirt. Solution was less voltage correction and richer idle.
//MartinL
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super7
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Re: Missfire with standalone

Inlägg av super7 »

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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bojke
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Re: Missfire with standalone

Inlägg av bojke »

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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super7
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Re: Missfire with standalone

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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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bojke
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Re: Missfire with standalone

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I can do that tomorrow because the car is in a distant garage.
bojke
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Re: Missfire with standalone

Inlägg av bojke »

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
mauser240
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Re: Missfire with standalone

Inlägg av mauser240 »

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.
//MartinL
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Re: Missfire with standalone

Inlägg av bojke »

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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Re: Missfire with standalone

Inlägg av mauser240 »

No. Even if the injectors are mached, difference may occure to uneven cylinder wear.
//MartinL
bojke
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Re: Missfire with standalone

Inlägg av bojke »

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.
mauser240
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Re: Missfire with standalone

Inlägg av mauser240 »

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.
//MartinL
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