Alright guys. Took the recently computer tuned car to the track. Previous best was 14.4@96.5 or so. Car was running 14.3's at a little over 97. Didn't understand it, so I took a datalog of the last 3 runs i did. To my shock and horror I was seeing up to 10.4 degrees of KR, ONLY directly after my shifts. This was obviously killing some performance. I have done some searching and come up with some things. I wanted to run them by you guys, as well as what I think of them:

Max retard vs MAP: I've heard that you can zero this table out. Now I am concerned that if I do this, and I get ACTUAL knock off WOT, it won't retard for me. Is this a valid concern? Any comments here?

Knock fast attack rate down, and knock retard recovery up: Seems to me this will slow the problem down and hasten recovery, but I will still get the retard.

Burst knock enable % differential air flow threshold: WTF? 3.1%? I don't understand this one. Can someone help here?

Burst knock enable coolant temp: 80 C, which is just under where I run. I have seen people recommend to raise this to a temp where you don't run (ie for me, I'd raise to 95). Not knowing the exact mechanism for burst knock, and the thought process behind it, I'm reluctant.

A few questions:
What is the difference between the spark retard tables and the knock retard tables? Is it that the KR tables are used if knock counts go up, and the spark tables are used for the spark correction vs map vs coolant temp?

Anyone have a good explanation of burst knock and how to use it?

Thanks guys
Jonota

 

Is that crickets I hear, or the higher ups don't want to share trade secrets???

Jonota

 

I feel your pain It's hard finding good information on our PCM's that relates to programming the pcm.

Sound logical to me about the knock retard and such. I have no idea what burst knock is... Do you have a LT4KM installed already?

Perhaps you want to find out why the knock is happening in the first place. I figure anytime you have to modify a spark retard table of any time you face the posibillity of reducing the protection it is trying to provide in the event of actual knock.

 

the problem you have is the sudden change in map pressure do to the closing of the throtle blades on the tb at the time of the shift. you can disable it with tuner cat theres a table fro knock retard vs map. just zero it out. and diable the burst knock thats has to do with the map pressure to (burst knock is in the constants table

 

So the spark retard vs Map table, I should turn the whole table to 0?

And the burst knock, set the coolant temp enable to higher than I run?

What were these tables intended to be used for?

I will certainly try these, thanks for the input.

Could a way to ascertain if this is the problem be to power shift, ie not let off the throttle when I shift? This would keep the map from going down enough to cause it to happen, wouldn't it?

Just some thoughts...

Jonota

 

no not REALLY BECAUST THE DROP IN RPM WILL CUASE A CHANGE IN MAP AS WELL. WHEN THE RPM DROPS IT CHANGES HOW MUCH AIR THE ENGINE IS TAKING IN. YOU CAN WATCH IT WITH DATAMASTER BY LOOKING AT THE AGPS THAT THE MAF IS READING.

I THINK THR STOCK BURST KNOCK TABLE IS SET AT 3%, MEANING THAT IF IT SEES A 3% OR MORE SUDDEN CHANGE IT WILL RETARD TIMING. I DONT KNOW HOW MUCH TIMING IT TAKES OUT PER AMOUNT OF % OF CHANGE SEEN.. THIS IS WORSE FOR SIX SPEEDS. IT JUST SEEMS MORE PREVILENT BECUASE A A4 JUST KEEPS THERE FOOT ON THE FLOOR.

 

So is it burst knock that I am experiencing? I would like to leave as much of the knock retard programming stock as I can, as I feel this is good protection for the engine. If I can just program out burst knock to fix this and leave the retard vs map tables only, that would be great...

Jonota

 

I'll try to offer advice from my experience.

If you want to reduce the max retard vs MAP, then you could drop it to 0 for 70-75kpa and above. That ensures that there is no retard based on the MAP for higher kpa regions.

I have the max retard vs RPM set to 0 from 3200 and above. It's set to a reasonable level below 3200, as is the MAP table for cases of high load, low RPM (real knock).

Reducing the KR attack rate to .750 and increasting the decay rate to .988 for 3200 and up will also help reduce the effects.

Setting the enable temp on burst knock will help keep that from becoming an issue as well. Also, reduce the number of DRPs for burst knock and it should go away quicker when it comes in.

I'm no pro, but I've made these changes or similar ones to my car and they seem to be working.

 

That sounds like my best option there. I think I will program in one of those things at a time and see how my retard during shifting responds....

thanks guys!!!

Jonota

 

It sounds like you just want to limit the amount of timing the car can take away with the knock sensor.

Why don't you just pull timnig and add fuel to the areas where the car is coming down to from a shift? Probally help with torque