Link E36G4X Idle Questions

[Ryno]

Need some schooling on my recent Turbo E34 (m50TU) project. This is my first build using a link ecu. 

I have the car up and running on 5psi. I have worked from the base map to get the car driving but I cannot get this consistent engine stalling to correct. I found a previous thread (linked below) addressing the same issue but the windows to make the adjustments discussed are nowhere to be found on my software. Maybe I am looking in the wrong places... I ran a log file of a warm start up and rev to 3k. Once throttle is let off engine will fall below idle and stall. Occasionally the engine will recover and not die but it is rare. 

Can someone take a look at my files and point me in the right direction. Any and all advice would be appreciated. Also point out any other issues that are possibly in my tune... again I am new to link tuning software. Looking forward to learning more!

E36 dying after warmed up and reving - G4+ - Link Engine Management Forums (linkecu.com)

 

[Adamw]

Start with these changes in orange for the fuel settings:

 

Calibrate your TPS so it is reading 0% at idle. 

Then the changes below for the idle settings.  The dashpot offset, hold and decay you just need to experiment with to get the nice entry into idle conditions without undershoot.  The target RPM may need to come up a bit, 700RPM is possibly a little on the low side.  

[Ryno]

Thanks Adam. Testing your settings this morning. 

[Ryno]

I made the recommended adjustments. Engine is still stalling. Here is a new log rev to 4k. From what I can tell as soon as the engine speed gets close to idle right before stalling it leans out. My AFR will go from 12-13 to 19-20. Adding fuel to the VE table from 0 to 500 engine speed has no noticable effect.

 

Let me know what you guys think.

 

*edit Also adjusted the target idle speed table to 800 rpm.  TPS is calibrated showing zero at closed.

 

 

[Ryno]

Made a few tweaks and it seems to be getting better now. Engine speed will still fall into the 3-400 range off rev. Stumbles for a second then returns to stable idle...

[Adamw]

15 hours ago, Adamw said:

Start with these changes in orange for the fuel settings:

Your log still shows no accel enrichment and overrun fuel cut is still active, so it doesnt look like you followed these instructions.  

You will also need to adjust your idle base position to match the new target RPM and the rest of the stall issue I would say just needs the dashpot function tuned.  

 

[Ryno]

1 hour ago, Adamw said:

Your log still shows no accel enrichment and overrun fuel cut is still active, so it doesnt look like you followed these instructions.  

You will also need to adjust your idle base position to match the new target RPM and the rest of the stall issue I would say just needs the dashpot function tuned.  

 

Completely missed the overrun fuel cut setting/ accel enrichment. Must of got confused. Thank you for the clarification. 

[Ryno]

On 5/21/2023 at 7:14 PM, Adamw said:

Your log still shows no accel enrichment and overrun fuel cut is still active, so it doesnt look like you followed these instructions.  

You will also need to adjust your idle base position to match the new target RPM and the rest of the stall issue I would say just needs the dashpot function tuned.  

 

Updated all the settings and the engine is no longer stalling. Thank you for your help and patience! 

[Ryno]

Update. Fuel and idle settings have corrected the engine stalling at stops/ coming off rev but now there is a new issue I am trying to correct.  Are the idle base position table values of 33 and 5% dashpot offset value causing my idle to now be about 1100 or so at full running temp? This is happening now when driving. Idle base position values are a percentage of the idle control valve open (if I am understanding correctly) so reducing this number will slow the idle down to a more acceptable sub 1k range? 

[Adamw]

Will need to see a log.  

[koracing]

PC log and the tune file ideally.

[Ryno]

 Correct me if I am wrong but I am guessing this has to do with speed lockout settings? The engine will idle up and surge but only when the car is moving. If the car is not moving the idle will stabilize within a second or two. In neutral (obviously) this will occur when coasting to a stoplight ect...

 

[Ryno]

Also still getting this as a result when revving the engine over 3k or so it seems. Engine will not return to idle. Stalls instantly. Adjusting idle base position seems to not have helped after all. The second log show the ECU almost lets the engine die. Battery light comes on just for a split second then recovers.

 

 

 

Sorry to be a pest guys. Im coming from MS1 and MS2 tuning software. I chose link because its a very powerful ECU that is tunable to be as reliable as my stock ecu. Lots of layers to learn... 

[Adamw]

You now need to tune the dash pot function so that it enters idle conditions nicely.  It is best to just do this using trial and error, set up a time plot with Eng speed on top of idle target, give the throttle a blip, watch how the RPM comes down and transitions to idle target - how much undershoot etc, then adjust one dash pot setting and give it another blip to see if its better or worse.  Repeat until you have got the right balance of offset/hold/decay.  

[koracing]

In all of those logs your base position is lower than that it takes to actually idle the motor.  I would set the base position 2-3% over what it actually idles at.

Further explanation: When you're idling at your target of 800rpm - your idle position is 36% in the logs.  Your base position at the same time is 33%.  So when it drops to 33% after you rev it falls below idle speed target.  I would set your base position to about 39-40% and let the closed loop timing and idle control bring the idle speed down to target from a point slightly over rpm target.  Basically just log idle position versus base when idling properly and make sure your base position is at or slightly above the reported idle position that is providing proper idle speed.  I would do this with dashpot of 0% and then work on adding some dashpot as well as play with the hold and delay times on dashpot to get a satisfactory return to idle. 

[Ryno]

 

log deleted

[Adamw]

Is there a question?  We need the tune file that was in use when the logs were made also.  

[Ryno]

Adam,

Sent you a PM last night with details.  I am still trying to sort out an engine stall on decel.  

Quick summary of where I am at as of now.

1. Idle base settings from 33 to 41 tested.

2. Dashpot hold/decay and offset tested from 0 to 10.

3 Stalling occurring (more when engine is fully warmed up). Example: Engine is coasting in gear coming to a stop 1500 to 1300 engine speed. Clutch depressed to shift out of gear into neutral. Engine immediately stalls. 

4. Log shows idle dropping below target when throttle is blipped. 

5. Speedlock out turned off (idle was raising to 1400 ish when car was moving at slow speeds) 

 

 

[koracing]

If you're holding it in gear until 1300-1500rpm, the idle control is trying to reduce the idle by decreasing base position but the drive train is keeping the rpm up.  So it keeps lowering idle postion then you push in the clutch and it dies.

So 2 things you can do after warming up fully:
1. raise up base throttle position or idle air bypass (mechanically add more air) until idle is close to warm target with idle base position in the 10-20% range.

This would require reworking your base position table as it will be off at all engine coolant temps, but this is the *best* approach I feel.

2. see what idle position provides good target warm idle and raise your minimum clamp to something just below this value. 

For example based on your last log the engine was idling at 800 rpm at about 36-37% idle duty/position.  When you coasted in gear until it was at 900 rpm and the idle control had worked the idle position down to 12% duty - then you pushed in the clutch and there wasn't enough air to keep the motor running.  So I would set your min clamp in this case to 37%. 

[Ryno]

Ok so min and max clamp settings here.

[Ryno]

^ Setting correct Min clamp fixed the stall issue. Thank you for your help Kris!!!

[Adamw]

10 hours ago, Ryno said:

Speedlock out turned off (idle was raising to 1400 ish when car was moving at slow speeds) 

This is your main problem, causing what Kris describes in his first sentence.  The purpose of the speed lockout is to stop the idle control winding the valve closed when you are rolling up to a stop in overrun.  

[essb00]

Enable your speed lockout, then maybe set it at 15-20km/hr.

You will be needing to fine adjust your idle base position table so it also does not raise your idle too much while slow coasting.

[koracing]

I believe he was having some erratic speed signal issues so disabled the speed lockout for now.

[Ryno]

Wondering if someone could take a look at my log file and give me some advice... Apparently still chasing the same issue where the engine will stall out (only when its hotter. it seems engine will not stall driving to work in the AM) 

I raised my idle set point to 43 from 37 to try and get the issue to correct but still same results. Could there be something else wrong here that I am missing?