Idle and dipping/stall issues

Hi all, greetings from the Netherlands. I’m new on HPA and enrolled on some courses (fundamentals EFI, AFR and practical standalone tuning). I have many videos to go but I want to understand what is happening with my car and learn from these forums and courses. I have no experience with mapping, so a lot to learn.

At the moment I have some idle issues with my car The car Opel Kadett GSi. It is a modified 2 liter turbo engine (C20LET/Turbo’d C20XE) sequential gearbox and running EMUBlack. With the previous antique standalone (KMS) and mechanical TB and ICV and different tuner the idle issues where way worse and almost undriveable on the street.

The car has now been mapped by a different tuner in Germany who also mapped my daily cars but maybe they are not familiar with ECUMaster. During cruising and under power it runs smooth/good and has enough power (500hp) available. For some reason I keep having idle issues even after a second map check.

Engine is built with complete forged internals, modified pistons, cams etc. etc. Running DBW now with a Bosch 74mm TB. The tuner says, that may be a little to big for the 2 liter, but others have also this size. Flywheel is also very lightened because of the sequential gearebox. I know the tuner tried to get the idle better, and after the second map check it is better, but not good enough and now also running way to rich.

The issues I have are:

- Idle is a bit high and stable, but Lambda is way too low/rich and not at target from what I can read in the software. Best idle RPM (also due to yearly test) should be 1000-1100 max. But I do not know if that is possible with the cams. I do not (yet) understand why it is not at target.

- After tapping the throttle it is idle dipping/wants to stall after getting back to idle. As it is not picking up the idle target. Same when hitting the clutch fe.

- I see different settings in the map 1 and 2 regions at lower rpm. Why would that be? (the map switch is for low boost and high boost

When it is idling and for example I turn my wheels, so the steering pump is asking power from the alternator, the car won’t stall and does correct the rpm a bit, that is why I do not understand why it wants to stall or stalls after tapping the throttle.

Attached the map and log file. (at the end of the log file I drive the car back in the garage, so that’s why the TPS changes)

I hope someone can point me in the right direction and help me with the issues.

Thanks in advance and best regards,

Roger

Hi guys,

Back again. I followed multiple courses and I have a bit more understanding from what the ECU and figures are telling me. So great courses! But to get back to topic, I really do not understand why the car is still dipping/stalling. I've tried some things but I can not get it better. The last test with minor changes did not make it any better (see attached).Driving the car is good and I have no issues with that. I know it is a difficult engine to run idle idle, also due to the very light flywheel, but the only problem I have now is after throttle dip/stall.

It still dips and often stalls after I give a bit of throttle, especially when it goes a bit up in MAP. When I slowly go up in rpm and let go it can handle it just, but more tapping the throttle (so fast change) it drops down to the 750RPM scale and stalls.

The engine does not want to run low in RPM due to the camshafts, so i have to accept the idle of 1100. Which is running smooth, although way to rich.

The other part I still not understand is why it is so rich at idle. When I adjust the VE table, it starts to hunt. (I switched off the PID in the idle section when adjusting the VE)

I found the warmup enrichment was still at 110 at 90 degrees, so I have changed that to 100. But no change at all.

Can anyone please push me in the right direction for what I can try?

Attached the complete log from today, but from 23:00 to the end is test map also added.

Thanks!

Hello everybody,

Many readers, but no reply's unfortunately. I wanted to give an update on my test this week. I drove the car to a quite place with a lot of wind to keep some cooling in to my radiator with the idea to keep the engine temp relatively stable at idle.

I started to uncheck the PID control and ign. correction and changed the settings in VE to get the base a bit less rich. After that tried to get the idle ref table as close to rpm target as possible. Unfortunately during the way I got lost in the settings and it started to oscillate more and more. Some how it just does not want to idle less rich and stable. the after throttle dip/stall was still there what ever I tried.

After this I reupload the original file and just drive a bit to see how that went. Driving, getting on throttle etc etc. is working perfect and the car runs smooth for exception for what happening is when driving with minimal load in lower gears at 2000-3000rpm the car is humping like hell. Is there a possibility that it goes in and out of idle control?

What is partially solved is when driving and hitting the clutch it stays 200 rpm above idle target and does not stall anymore. This is also in the settings.

But another issue I have now is something I do not understand. It is visible in the log at 1.13:00. The engine sometimes keeps running at 2000-2200 rpm with no tps and low wheelspeed. also when stopping it stays at that rpm. Giving it a throttle blib not always settles it down to idle speed and sometimes takes few seconds.

I noticed the wheelspeed sensors sometime show at lot of noise but I think my sequential gearbox vibrations are causing this, and need to check that but that should not be causing the >2000rpm rise.

thanks!

have you checked for vacuum leaks? This can cause some odd idle behavior

Also with your wheel speed sensors. I can't imagine vibrations should cause noise. Wheel speed sensors are a high frequency sensor which means they are susceptible to electrical interference. Usually with most wheel speed sensors they require using shielded wire, with the shield property grounded at one end as well has having a reliable power source that's clean. Eg an output from the ECU.

And now that you are using a DBW throttle body, what did you do to remove the old idle control valve? Is it blocked off on both ends, or was it left in place?

When the idle control valve is not part of the throttle body you have to make sure its properly blocked off, as if it lets air through it can cause your idle to be all over the place as the DBW is chasing a ghost so to speak

Hi Paul,

Thanks for your reply.

Everything is checked for possible leaks, as that was my first thought too.

I've installed the speed sensors with shielded wire. Rears are oem, fronts are oem, but changed position due to Pilbeam strut setup. But I will investigate that in a later stadium. It is originally a car from the 1989, although the sensors are brand new, it's old technic. The only thing I can imagine is the vibration through the shafts in to the pulse wheel. That could fe. mean the distance between the sensor and pulse wheel is not correct.

The DBW is installed instead of the old cable TB. The C20XE/C20LET old set up had a bosch 2 pin ICV which was connected via hoses. Every thing is modified, and no connections left to create a leakage path.

Something tells me there are some settings or mis reading which is causing al these problems, but my noob knowledge is not yet finding it haha.

Is the ecu set up with idle fuel and ignition tables separate to the main map? These seem to cause more problems than anything in most cases.

If there was closed loop ignition control that may have been part of the problem with the high rolling "idle" seeing different ignition timing.

To assist in stabilising idle you probably want to create an ignition timing "hole" around target idle speed, if it drops it generates its own additional recovery torque.

may not be what you want to hear if it has to pass emissions testing but an engine with aggressive cams and lighter rotating assembly will probably be more stable around 0.87 lambda than stoic too.

Hi Michael,

Yesterday evening some one remotely checked in while I drove to a location. He managed to get some things better and most of the issues are solved.

I do not know exactly what is changed, but will ask him a short summary.

There were some changes in different areas and set points. I need to change my plugs to see if it gets a bit better and a followup is planned. (Due to long rich idling the plugs may be fouled a bit)

About the emissions test, It is now running 0.90. When I refit the cat.converter for the test I expect it to pass.

Only thing that is left that I have a missing tooth error at wot from 3000rpm upwards. I just checked the wiring and that is good. New sensor is ordered and than I will make a new test.