All Things Mk5 > Performance Modifications

Timing pull, knock?

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Zephyr:
Hi guys, I have a Stage 2+ CDL TFSI and when logging I see some timing pull of around -5 degrees.

When I add some octane booster these values drop to around -1.5 to -0.5, is this likely genuine knock the ECU is picking up on?

There are no misfires etc when driving but it does sometimes feel like its holding back.

Is -5 too high and dangerous for the engine? I have read that the stock software can pull up to around -9 but I dont know how true this is.

Please see the logs here - http://www.mediafire.com/file/19kfjv3kuydt4mh/TFSI+LOGS.rar/file

Thanks!

pudding:
Knock control is weird in the Bosch Motronic/MED ECUs.  The numbers you see in the logs are units of retard, one unit is 0.75 degrees, so -5 would be -3.75 actual degrees. Don’t ask why Bosch do it that way as I have no idea!

Anyway, yes stock engines run on the edge of knock, but -9 sounds far fetched to me. My stock map shows nothing on a good day and -3 on a bad one. Remaps can easily run higher levels of retard. Loads of fuel smoke out the back is usually a sign of timing pull and/or EGT control dumping fuel in.

-3.75 isn’t a lot tbh. What map is it? Can you trim the timing with it? That’s one advantage of the Revo map if you have an SPS.

A good timing target is around 15 degrees advance in boost, so if it’s pulling back you will definitely feel it. 5+ real degrees is when I would look to adjust the map personally.

Zephyr:

--- Quote from: Pudding on September 11, 2020, 03:48:30 pm ---Knock control is weird in the Bosch Motronic/MED ECUs.  The numbers you see in the logs are units of retard, one unit is 0.75 degrees, so -5 would be -3.75 actual degrees. Don’t ask why Bosch do it that way as I have no idea!

Anyway, yes stock engines run on the edge of knock, but -9 sounds far fetched to me. My stock map shows nothing on a good day and -3 on a bad one. Remaps can easily run higher levels of retard. Loads of fuel smoke out the back is usually a sign of timing pull and/or EGT control dumping fuel in.

-3.75 isn’t a lot tbh. What map is it? Can you trim the timing with it? That’s one advantage of the Revo map if you have an SPS.

A good timing target is around 15 degrees advance in boost, so if it’s pulling back you will definitely feel it. 5+ real degrees is when I would look to adjust the map personally.

--- End quote ---

Thanks for the reply :) Looking at the logs with octane booster I have 16-17 degrees of timing at redline, even without the booster lambda request vs actual stays at .82 so I dont think its dumping in fuel. The car is tuned by Revlimit GR in greece.

MichaelRew:
I am building a twin tubo 408W with a blow through carb. I would like to add a knock sensor to retard the timing. Anyone out there have info on DIY knock sensor/timing control for carb aplications?

variant4

pudding:
I think you are confusing ancient old American V8s with modern DI engines  :grin: 

German engines haven't run carbs since the 1980s.  Wrong car, wrong forum fella.

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