NefMoto

I have a very annoying lifter-like noise on my 1.8T S3. I know for a fact that it's not the lifters, it's not the cam valve, nor the cam chain (all new and/or tested separately). I also have just rebuilt my engine and there's no piston slap as well since block and pistons came from a perfectly working and quiet car.

The weird thing is that when I set the idle rpm to stock (720-760) the chatter goes away. However, since I have a solid steel flywheel I get a really annoying gearbox rattle at this rpm, despite the sprung clutch plate, so I keep it at 960 (but then I have that lifter-like noise again). Also, when the A/C is on and idle load goes up to about 30%, that noise almost disappears. With a slight throttle up to about 1600 rpm the noise persists, and above 1600 it completely goes away.  I notice only very slight improvement when oil gets hot > 90C.

I tried playing with load via KFMIRL and KFMIOP at idle just for the heck of it, got it up to about 30% (same as when a/c is on), but that did not help. Played with ignition timing at idle, went from about 1KW retard to about 9-12 advance, did not affect anything. The only thing is lowering the rpm.

First question is has anyone experienced something like this and if not, maybe what should I look at to possibly make the idle at low rpm little smoother to possibly reduce that gearbox chatter?

I run 630cc Bosch injectors, my injector times are about 1.36-1.70ms at idle and load with stock KFMIRL/KFMIOP is about 18-20%. I have perfect idle and no gearbox chatter at anything between 860-960, but below 860 it starts to rattle.

Thanks

2500 rpm idle.  Job done.

Tried about 1600, but did not like it at all :)

Do not change IRL/IOP if you want more idle load. Bump idle torque reserve.

I've upped from 1.27 to 1.82 at the rpm of interest ... what are appropriate limits? 10x

;D ;D ;D ;D

99% sure it will be the evap system

Is it coming from the drivers side? (UK)

And the 1% wins :) I don't have EVAP on my car and the noise is coming from the exhaust side of the engine, not the side. I am getting tired of these little problems and unless I manage to make the car idle at about 30% load "the right way" and feel right, I will just let it go. The torque reserve did not seem change my idle load. If IRL/IOP are not ok to tweak that, what are my other options?

fix exhaust

The exhaust is not leaking, I am just saying that this is the direction where the noise is coming from, but it's definitely on the engine's side, not exhaust manifold. I wonder if it can be any spark related noise, I tried different spark plugs though, no change. I will post a video or something when I get the chance.

The question is can anyone give me some pointers how I can make the car run about 30% load at idle the correct way. I'd like to try how that feels and if it kills the noise like it happens when the A/C is on. It was brought up that KFMIRL/KFMIOP is not the right way to go and torque reserve did not help. What are possible other options?

try increasing a little bit more..say all the revs at 2.5...and see.

Went to 5, then to 10, idle was 21-22% with both settings, don't think that's it.

Went up to 25, but still did not see a change in load, only slight ignition retard. Wanted to log dmrllr_w to see what's the actual torque reserve output, but I don't seem to have this in the variables list for Me7Logger. Has anyone logged another variable related to torque reserve to possibly see if changing KFMRES produces expected result?

Aside from that I raised the idle rpm to 1100 and when warm the car is not so noisy anymore.

The reason why torque reserve did not work for me was because my KFZWMN -  Minimum ignition angle table was set too high for some reason. This prevented timing to be pulled back and therefore no effect from the torque reserve. After setting KFZWMN to stock everything started working as expected. I was actually able to get a more buttery idle with more idle load, about 26% at a more reasonable 960rpm.

Why would one increase Minimum ignition angle table, isn't that a safety table? Mine was set like this:

1.50   1.50   1.50   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   6.00   6.75   7.50   8.25   10.50
1.50   1.50   1.50   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   6.75
1.50   1.50   1.50   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25
5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25
5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25
5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25
5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25
5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25
5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25   5.25
4.50   4.50   4.50   4.50   4.50   4.50   4.50   4.50   4.50   4.50   4.50   4.50   4.50   4.50   4.50   4.50
3.75   3.75   3.75   3.75   3.75   3.75   3.75   3.75   3.75   3.75   3.75   3.75   3.75   3.75   3.75   3.75
3.00   3.00   3.00   3.00   3.00   3.00   3.00   3.00   3.00   3.00   3.00   3.00   3.00   3.00   3.00   3.00

and stock is:

-7.500   -7.500   -6.750   -6.000   -3.000   -0.750    1.500   3.000     3.750    4.500    5.250    6.000     6.750     7.500   8.250     10.50
-8.250   -8.250   -7.500   -6.750   -5.250   -3.750   -2.250   -0.750   0.000    0.750    1.500    2.250     3.000     3.750   4.500     6.750
-9.750   -9.750   -9.000   -8.250   -7.500   -6.000   -5.250   -3.750   -2.250   -0.750   0.000    0.750     1.500     2.250   3.000     4.500
-11.25   -11.25   -10.50   -9.750   -9.000   -8.250   -6.750   -5.250   -3.750   -3.000   -2.250   -1.500   -0.750   0.000   0.750     1.500
-12.00   -12.00   -11.25   -10.50   -9.750   -9.000   -7.500   -6.750   -5.250   -4.500   -3.750   -3.000   -2.250   -1.500   -1.500   -0.750
-12.75   -12.75   -12.00   -11.25   -10.50   -9.750   -8.250   -7.500   -6.000   -5.250   -4.500   -3.750   -3.000   -2.250   -2.250   -2.250
-13.50   -13.50   -12.75   -12.00   -11.25   -10.50   -9.000   -8.250   -7.500   -6.750   -6.000   -5.250   -4.500   -3.750   -3.750   -3.750
-14.25   -14.25   -13.50   -12.75   -12.00   -11.25   -9.750   -9.000   -8.250   -7.500   -6.750   -6.000   -5.250   -4.500   -4.500   -4.500
-15.75   -15.75   -15.00   -14.25   -13.50   -12.75   -11.25   -10.50   -9.750   -9.000   -8.250   -7.500   -6.750   -6.000   -6.000   -6.000
-16.50   -16.50   -15.75   -15.00   -14.25   -13.50   -12.00   -11.25   -10.50   -9.750   -9.000   -8.250   -7.500   -6.750   -6.750   -6.750
-17.25   -17.25   -16.50   -15.75   -15.00   -14.25   -12.75   -12.00   -11.25   -10.50   -9.750   -9.000   -8.250   -7.500   -7.500   -7.500
-17.25   -17.25   -16.50   -15.75   -15.00   -14.25   -12.75   -12.00   -11.25   -10.50   -9.750   -9.000   -8.250   -7.500   -7.500   -7.500

There is NO reason to reduce minimum ignition angle. Terrible.

That could easily grenade your motor if KR isn't allowed to do its thing.

Fire your tuner :)

I had 630cc Siemens Deka at some point and my idle was simply awful. The 20v motor does not like the Dekas. At this point he was trying to fix that for me and I assume this change was part of that and he simply forgot to bring it back once I changed the injectors with correct ones (630cc Bosch 0 280 158 123, dual cone spray pattern). With these the idle is 100% stock.

Unfortunately I will never know, my tuner passed away not long ago, may he rest in peace!

Also it might be worth mentioning if idle torque reserve is increased, KFMDKO - map for torque needed for air condition should be decreased accordingly. Otherwise you get crazy high load and injection timing on idle when the A/C is on. At least this is my understanding, correct me if I'm wrong.