Anyone else have this problem?
 

Hey guys and gals, so I’ve been battling this for months now but I just can’t get it. Only with the AC on, when depressing the clutch to come to a stop or whatever, the idle dips on return to idle speed and sometimes it’ll kill the engine. I’ve tried everything from adding more idle effort on the AC and verified my closed loop setting are good. Clutch switch is working correctly as well as the neutral switch. Kind stumped as it only happens with the AC on. With the AC off, it returns to idle without dipping or stalling the car. Fuel map is good and was tuned.

One thing I do notice which I believe might be the culprit is that only with the AC on, when depressing the clutch to come to idle, I see the “Overrun” flag pop up which leads me to believe is what’s causing the dip. It also shows the flag when free revving with AC on and will dip/try to stall coming down.

It’s a S8 PnP Adaptronic modular on a 1996 FD.

Thanks!

Look into idle ignition control. It’s a very good tool.

Hi Johnny,

It sounds like you have tried a few amount of different things. I would suggest first off doing a vacuum / boost leak test - For the stock twins you block off 1 intake and use a PVC pipe cap with a universal valve stem (all things you can get from a hardware store) I suggest using an air chuck that allows you to see how much pressure you are adding into the system. You should be able to hold 10 psi for about 5 seconds or so.

Secondly I suggest you warm up the car to operating temps. Then unplug the IACV. If the car dies you will need to raise the Mechanical idle to match the target idle. My suggestion is to set the mechanical idle with the FANs OFF and the AC OFF. Essentially no load. Then re-calibrate your TPS and set your load offsets so that when they turn off you do not get a stall.

Once these have all been done you can also check the check box Automatically detect neutral. I find this helps the ECU go into Neutral state more effectively.

Hope this helps.

Cheers,
Shawn Christenson

Not sure in what world this would be caused by a vacuum leak when it idles fine without the AC off, it seems to me that it is mostly tied to something electrical in the ECU triggering the over run condition only when the AC is on. Whether this be hardware failure or tune file setup, I can't say. Unless the overrun condition is somehow flagged for different settings when the AC is active and causing it to be active way too low, then those items shouldn't be related. Regardless of what rpm the car is idling at and how much ISC idle effort is being used to hold that, the overrun-flag-in-AC-only event should not be happening and won't be solved by fixing a vacuum leak or resetting idle. Comon' now.

Has it worked fine prior to now and this issue just start happening? If that is the case I'd think it would most likely be a hardware failure. If you'll send me the ecu file that you're using I can take a look and least determine if its an issue with the tune file setup or rule that out.

Skeese

Skeese

Thank you for this information, I will try it out and see what happens. I have set my mechanical idle to just below target idle with no load. Then set up my idle effort gains for my fans and AC afterwards. It’s really weird as it only happens with the AC on.

when I first got the modular ecu (September 2018?) and had it tuned while I was still running the stock twins, it worked just fine. Then in 2019 when I went single turbo and had it tuned... it started doing this problem. Only with AC on. Very weird as without AC it doesn’t dip or try to stall. Been banging my head as to what this could be. I’ll try and send you a ECU file during my days off this week. Thanks for the help!

I'm wondering if there is a bug in the software that came from one of the updates since then? Do you know if you've updated the software/firmware since. If so, you could always try reverting back to the old version to eliminate the potential that it was related to a bug in there. I don't keep on on all the adaptronic update so I can't say but I'd think that between a check of the ECU file to ensure nothing was tied to AC that shouldn't be and verification that it didn't come from a software/firmware update bug that would rule out all the options but a failure of the hardware.

Skeese

I doubt there is a bug in the software or we would see more problems with this, at minimum I would not suspect this first. since you are getting an overrun flag with the a/c on look at your overrun settings, how close is "disable fuel cut below" to your target idle with a/c on? if it is close it may not turn fueling back on in time to catch the engine causing a dip/ stall. there is an option to turn off overrun with the a/c on but it shouldn't be necessary with the right settings.

This is why I suggested posting or checking the file to determine if anything is tied to the overrun that shouldnt be. I can't make that assessment without a file so the next question becomes when did it start to determine if that can be tied to software update bug or hardware failure, both of which are excessively common with this platform so it warrants consideration.

Skeese

agreed posting the file up will lead us in the direction of the problem. a bug is worth consideration but as I think we agree, it would be wise to rule out a simple settings problem before going down that rabbit hole that we have no way of fixing. that is unless Adaptronic decides to open source the code.

Hey guys, as promised here is the ecu file. Sorry for the delay as it's been hectic out here for me. Thanks again for all the info you guys are throwing my way!

I took a quick look over your file and everything seems ok except your a/c effort looks a little low to me but may be ok and your neutral timeout looks long, I don't see any reason why the ecu should wait 5 seconds before entering closed loop and waiting that long may stall the engine before closed loop corrects the idle duty. try 3 seconds there and see how that works, also a log of the problem may provide insight into what the ecu is doing when the problem happens.

it was at 3 seconds before and I upped it to 5 seconds per Andy’s video on closed loop idle control. I’ll try to bring it back down. My car is in the shop for inspection now so when I get it back next week I’ll post a log of the problem. I’ll look through my recorded logs as I believe I may already have one showing the symptom.

yea not sure that is going to fix the problem but that did stand out to me as a bit long. a log of the problem will be best to see what the ecu is commanding when the problem happens.

Well i got my car back from inspection and i went out for little drive with the AC on the whole time. I've attached both log file and the tune file. You can see where i accelerate and then just throw the clutch in and it will dip down and then come back up and settle back down to idle. Somewhere in the middle of the log you will see one time where it actually stalled the engine when i threw the clutch in. Towards the end of the log i was free revving the engine to about 4k and letting go of the throttle and you'll see it want to die out. Thanks again for all your time and help! :)

Hi Johnny,

If you have confirmed you do no have a vacuum leak my next suggestion is to go to - idle settings - closed loop control - Click View / Edit Table on the idle ignition timing trim - Zero out the negative timing. What I have found is this drops the tq so much in some applications that it stalls the engine. I find most rotaries do not need this negative trim.

Cheers,

Shawn Christenson

From the log you posted it looks like it is going into overrun and not recovering. I am not certain that is the case because the .csv files leave out a lot of useful information, could you post the original .alg file of that same log. agreed about zeroing out the negative timing on idle ignition trim.

Thanks for that info Shawn, but i have confirmed there are no vacuum leaks and i have tried and zero'd out the negative ignition trim in the idle control section before and no luck as i saw you post that in another thread, and I changed it back to how it was due to it not working for me.

7sins, i compressed the ALG file into zip as it was telling me a .alg file is unsupported for upload.

ok i played back your log and it looks like it is going from overrun cut into lean out cut when the engine dies. try turning off lean out margin under engine protection and see if it still dies, also try removing that negative timing and see if that helps with the dipping on idle return. if that stops the dying we will adjust your lean out margin settings in your overrun ranges as your wideband outputs a large range, i was seeing almost 80 when the engine dies which is triggering your lean out margin protection.

thank for that info! I was having Problems with the lean out margin before and I fixed it. Gave me a dead spot around 3-4K Rpms when inputting throttle again. I’m taking my bike forks to the shop right now to redo the oil seals. I’ll take my car and log the trip with the lean out Margin protection off.

Took two logs going to and from the shop. In the first log ending in 144 you will see that it stalled out on me sometime around the first couple minutes of the drive. Unfortunately still showing the same symptoms. Before heading out i double checked my mechanical idle and raised it up closer to target idle(i had it around 900-920rpm and then added effort to get it to 1000. Now the mechanical idle is around 980-990rpm), adjusted idle efforts in no load and load conditions. I also took off negative idle trim as well. You think a dirty IACV would have something to do with this? I haven't cleaned it out in the 2 years I've owned the car, mostly because it never gave me any issues that would make me believe it was a dirty IACV.

Doubtful the ISC valve is causing this issue, I am still seeing it lean out to the moon and overrun stayed on well past where it should have. let's try disabling overrun and see if the symptoms stop, this is a temporary test to see if overrun is in fact staying on too long. also try not to make any other changes in the mean time so we can keep the variables down. try that and post up another log and your current ecu settings and we will go from there, read settings directly from the ecu and save it to a new file.

I would suggest engaging the services of a competent Adaptronic tuner to look at the issue. Sounds like a mapping issue to me...

It was tuned by a competent adaptronic tuner. He did not tune it with the AC running which is why it could've been missed. Like said before with the AC OFF it runs like a champ without hiccups or dipping returning to idle.

I went out for a quick drive this morning with the overrun disabled and it went a lot better it didn't dip to the point that i would notice it or it would want to die. You will see at the end of the log where i free rev it, it'll drop just a little bit but I'm pretty sure that might just be that it needs a little fuel down around the idle and below idle areas. But the actual dipping and wanting to stall out while driving did stop which is why i thought it was a overrun problem. But let me know what you think! :)

yea that looks a lot better I am not seeing the severe lean spikes and the engine stays running. so now what I would do is re-introduce engine overrun and turn up the "disable fuel cut above" and "go into fuel cut below" settings until you get a nice idle recovery. also you can reintroduce the lean out margin but use '100' in your vacuum areas as you don't want lean out margin to be able to go into protect while in vacuum ranges. as far as the dipping goes I do see a bit of a lean condition but it looks like it is happening after the idle recovers. I would try increasing your ignition trim advance, start with 10 at -50 rpm and interpolate up to 15 at -200 and see if that helps. you are already not running much advance in the idle area so this may help. my half bridge recovers nicely with those settings but it may be too much for a street port or stock ports.

try adjusting the idle trim first and see if that helps solve the dipping, if it starts hunting it is too much. after that try reintroducing overrun and lean out margin.