erratic idle after tune and general question about global knock count

[samurai_79]

I have a modified Mini R53 engine (aftermarket Thumper TPR2 head, TVS 900 supercharger and Schrick Cam) for which I recently had a G4+ installed.

For reference, additionally to the ECU the following components were also installed prio to the tune:

• AEM X-Series Breitband UEGO AFR wideband controller 30-0300A
• CatCams 469 cam
• 550 injectors
• smaller SC pulley (60mm, coming from 70mm)
   

The car was running fine with the OEM ECU and previous parts. The tune it got on the G4+ + having the new parts installed obviously helped it a lot and it is also running well overall and I am really happy so far,  BUT the way the engine now comes back to idle after coming off the throttle is quite odd IMHO.

IDLE Questions
The following idle issues occur (please bear with me as I am firstly a noob to ECU tuning altogether and my technical/engineering background is limited - so basically some of the worst credentials to be doing a deep dive into this whole topic in general):

1. When coming off higher engine loads (throttle position usually > 50% & always  > 3,000 RPM) and letting the engine "run out"  (throttle position = 0) idle rpm drops well under 1,000rpm and the engine almost dies/stalls (EML light shortrly lights up as when it stalls). It then feels like it tries to counteract that by reving up shortly with a short "blip" up to 2.000 rpm. The engine/ECU keeps doing that over and over again if I let it.
2. When @ < 3,000rpms and laying off the thottle it only slightly dips under 1,000rpm and then also only slightly goes up as above but only once and only up to about 1.200rpm - and then is stops doing it (as opposed to the above described behaviour). With this I could live - the afore mentioned issue #1 is a real pain though...
3. When in lower rpms (<3,000rpm) and during mellow driving / cruising and changing gears and as soon as I lay off the throttle, the rpms shortly "blip" up or hover before I change into another gear.

I've tried looking at idle control but can't seem to find any anomalies. Could it be realted to the wideband sensor/controler? (.pclr file and log attached for reference)

Knock Count question
Also, I've gotten a global knock count of 10 on my last logged drive (including spirited revving up to the limiter) Is this something to worry about or can I disregard this? I'm told these knocks can be disregarded - if so, the only question is how can I tell when it's becoming critical? For me personally, any number > 5 in my global knock count after a short drive is critical or am I being to picky about it?

Log 2019-05-6 8;39;17 pm.llg

 

 

Thank you in advance for any input you might have on how I could get this sorted out (specially the above mentioned idle issues)

Cheers

[Adamw]

I would say the knock threshold is set up a little too conservative as there is not much of a margin above the normal engine noise in your log.  Also, it has been set up to not take any action - it is only logging knock - not trying to control it by retarding ignition.

As for the idle there is no idle recorded in it and there are not enough idle related channels being logged to see the cause.  It would be better to do a PC log to capture a fuller picture.  I see a couple of settings that are probably contributing though so you could try correcting these initially:

Change the AP/TP lockout to about 1%.  Set the RPM lockout to about 400RPM.  Set the speed lock out to driven wheel speed and 4kmh.  With the current settings it will be closing the throttle trying to control the idle when you are still coasting.

 

In the E-throttle target table set the two cells in the Top left to 3%, the current 8% is probably causing the blip when it nearly stalls.

 

 

[cj]

Adam beat me to it but i'd already written out most of this so here goes...

There are a fair few things "different" with your idle tuning. That log only contains a dozen parameters so we cant fully understand what's going on, but comparing it against the tune a few things jump out. As a basic rule, air(throttle) + timing = more power. If you take either one away, you lose power, and fundamentally, idle is just maintaining a constant (quite low) power output.

1) you have a 4D ignition table that is set to pull anywhere from 5 to 24* of ignition timing as soon as you get off the throttle. It looks like this was set up kind of to replace ignition idle control but i'm not sure why. It means that at pretty much any time you are off throttle, you are running at near 0 ignition angle (between -5 and +5 most of your log), and it will want to stall unless you have HEAPS of throttle open (probably ~10% at a guess). Your ethrottle target table is within the normal range (~3% TPS at idle), so you should probably have 10-20* of timing to match this.

2) your throttle idle control is set up with no speed cutout (so its always active if the RPM +throttle criteria match). Normally you dont want this and would set it to 20kph or similar.

3) your throttle idle control RPM limit is set to 1400rpm. This means throttle idle control is active at any point under about 2500rpm (~1k target + 1400). this rpm lockout should probably be more like 4-500.

4) throttle idle control AP/TP lockout is set to 4%. on an ethrottle like this that means 4% AP, which is actually quite a bit, and means at any low-ish throttle pedal angle, its still going to try and idle, rather than go slowly. Normally this is set to <1%.

5) your ignition idle settings do not line up with your throttle idle settings. Ignition idle values essentially replace any IGN1 table or 4d table values when this is active. It is currently very aggressive however (ign=0 when 500rpm high, and 40 when rpm is 500 low), and again has a 6% AP threshold which is quite high, and because it comes in at 1800rpm, as soon as you drop down into this range it will cut timing quite savagely making it want to stall.

All this adds up to at least 3 different parts of the tune pulling a LOT of timing whenever you are off the throttle, even for a bit. even if it doesn't stall its got to make it feel a bit flat as far as throttle response goes. First thing i'd do is turn off that 4d ignition table, then set the thresholds for idle control to 1%AP, 400rpm, and 20kph, and ignition idle control to 1400rpm, 1%AP, and 20kph. I'd then set the idle ignition table to only add/remove 3-4 degrees per 100rpm instead of the 10 or so per 100rpm it does now. Also, temporarily change the idle control from closed loop to open so you can get the bascis right, then turn closed loop back on just to keep to steady (if you even need to, it can be quite happy on open loop idle)

This will all make it feel quite different, and might be worse in some regards, but its a lot better starting point to fix it up from.

[samurai_79]

Brilliant! Thanks so much for your answers/recommendations - they are VERY much appreciated.

I will give them a try it and will report back on how they worked for me.
Cheers