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Author Topic: RS4 B5 8D0907551K Idle Missfire  (Read 3208 times)
OberlandRacing
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« on: April 04, 2023, 12:43:34 PM »

Hello,
I´ve bought an RS4 with a Tune.
Car has TTH510 Turbos and 2.8 Heads with ori cams. 
Also its converted to TFSI Ignition Coils and an Additional Harness, so no more "power amplifier" on the Airbox.

I have problems with idle Missfire on Cylinder´s 2, 4 and 5.
I´ve checked the flash and the most ones are Stock.
TVUB, FKKS, TEMIN (Car has stock injectors), MLHFM, MLOFS, MLMAX are stock, so i assume there is a mechanical problem.
Car runs great when u leave idle. 

But, someone maybe know what maps i should also check?
Just to make shure there is nothing wrong with the maps. But i think i have to search for the issue on the car  Huh
Thanks

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Audi S4 B5 2.7 AGB FL
Audi A4 B5 1.8T ANB FL
prj
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« Reply #1 on: April 04, 2023, 02:00:14 PM »

Upgraded turbos but stock injectors? KRKTE also stock?
The car is out of injectors on stock turbos already, if you just tighten the wastegate springs a bit...

The 2.8 heads are not helping you, and if injectors are stock, get them bench tested.
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OberlandRacing
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« Reply #2 on: April 05, 2023, 02:20:42 PM »

KRKTE is also Stock.
LAMFA is touched by the last to rows to 0.82 for safety i think..
KFLBTS also slighty adjustet to run rich..
KFLDHBN is just in the middle adjustet by 0.2

The 2.8 Heads were installed becauses the original ones had cracks between Plug and Valve-Seat.
But, all those Maps are not for Idle..
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BlackT
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« Reply #3 on: April 05, 2023, 03:31:53 PM »

Check injectors
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prj
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« Reply #4 on: April 05, 2023, 04:19:39 PM »

Bench test injectors and use logger to check injector duty cycle. Log ti_w vs rpm and calculate it.
It's either running super lean (out of injectors) or making fuck all power. No two ways about it.

For idle, if injectors turn out OK then it's the heads and injector angle not agreeing.
Only thing you will be able to do is raise kfmres a bunch. But I would not recommend it until you make sure that the injectors are ok. This super lean setup and a malfunctioning injector can easily lead to molten cylinders.
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