engine stalls at stops/clutch disengage FD RX-7 drive-by-wire

[SchuKingR]

Hey guys, I have a problem with my engine stalling when I'm disengaging the clutch right before a stop.

log file: https://drive.google.com/file/d/14AjoXD_bfFmJZk6Z4kxftiBuGgxcWZar/view?usp=sharing

pclink file attached.

 

Car is a Mazda FD with oem twinturbos and standard ports equipped with a G4+ Thunder. OEM throttle is controlled by an BMW actuator from a S54. Compression is good (7,7 bar all around).

FD3S_Thunder_MAP_V54.pclr

[koracing]

When it's idling at the target rpm, the throttle is at 3.9% open but your idle base position is 1.6 with a E-throttle target of 1.5 (total to 3.1%).  Normally I would say you should target a higher value than what it actually requires to idle correctly - like set the minimum E-throttle target to 3.5 and idle base position to 0.8-1.0 so that you get a total of 4.3-4.5 and then the close loop idle will bring it down slightly as will the timing control. Your e-throttle target table looks like it's set up to limit throttle position based on time at WOT, but you can gain RPM targetting to help as well by going to 2 tables and have them switched by your virtual aux 1.  Your base timing table is all 3 degrees around idle.  I don't know if this is normal as I've never fully tuned a rotary engine, but I would increase all the base timing below idle target on the base table to improve it's tendancy to idle up if it drops into the lower rpms before idle control has a chance to improve things.  I'm attaching a link to your tune file modified in these ways you can take a look at or try.

https://www.dropbox.com/s/wkktx1hxwpwk1dc/FD3S_Thunder_MAP_V54-Modified E-Throttle Target.pclr?dl=0

[Adamw]

I agree with KO that it looks like it needs at least another 0.5% in the top row of your e-throttle target table. I would make the idle ign a bit more aggressive too, something like below.  But there are a couple of odd stalls in that log which make me think there may be something else going on sometimes, for example at time 16:21 it has been idling with the car stationary for some time, with throttle at about 4% and ign timing at about 4deg, then RPM suddenly starts to drop, ign timing ramps up to 13deg and the throttle opens to 16%, but it still stalls.  Is it maybe not enough accel enrichment or similar?  You could possibly do with just a tiny bit more integral gain on the e-throttle settings too, maybe try 0.07, you can see a little long-term position error in some places where TP is sitting at about 0.5% lower than target.  DBW with linkages is sometimes hard to eliminate small error like that due to a little bit of backlash in the linkages. 

Only the primary port butterfly is working at idle right? 

 

[SchuKingR]

hey guys. first of all thanks for the hints, I will try to go for a test drive tomorrow with the changes. I think I didn't tune the accel enrichment yet, so I will try to add a bit there. At 16:21 I think that was my brother in law starting to drive. He is not used to the car, so I think he just stalled it there.

I will also try the integral on the e-throttle, but as you say, DBW with linkage is a pain. I tried various different settings, so I can drive without the ECU shutting down the DBW.

And yes, I think only the primary port is working at idle. I think the secondary port opens later with the linkage, but I need to check that. I can try to hold the doublethrottle blades in the upper manifold closed.

The limit in the throttle position table is for our noise emission test here in germany. So the car is somewhat quiet there. As quiet as a rotary can be with a 3" exhaust  I like the version with the two tables! Thanks!

[Pete_89t2]

2 hours ago, SchuKingR said:

And yes, I think only the primary port is working at idle. I think the secondary port opens later with the linkage, but I need to check that. I can try to hold the doublethrottle blades in the upper manifold closed.

 

^That is correct, the FD's secondary throttle plates are mechanically linked to the primary throttle plate, but they should not start to open until the car is revving well past a high idle speed on a cold starts (about >1500 RPMs).

[SchuKingR]

Back from my test drive. It's heaps better than before. Car just stalled once where it wasn't fully warmed up. Most of the time it drops down to like 450rpm and then climbs back up.

Some weird stuff happend at the end as I parked the car in my garage. First it was idling well and all of a sudden the RPM starts to wave up und down as well as the TP. Could this be my idle proportional gain is set to high? Gave it a little throttle blip and the wave was gone.

Log file: https://drive.google.com/file/d/14BZJMqfH0i8A46M1iejsa_pzS7_3AwHR/view?usp=sharing

 

FD3S_Thunder_MAP_V55.pclr

[koracing]

I would change your anti-stall gain to a much lower value - currently all 25, maybe try 5, and also raise your overrun fuel cut deactivation rpm table values by like 400rpm warm at least.  Your cold stalling shows the rpm spike from 450rpm to 4000+rpm - not sure if that actually happened or it was a trigger mistake.

[SchuKingR]

Thanks! I will try that, hopefully tomorrow. But what I don't understand, why lower the anti-stall gain? Or could this have caused the strange idle stuff in my garage?

and yes, I think the 4000rpm thing was a trigger error.

[Adamw]

With too much gain the throttle will move faster than the engine responds to the change in air flow so you end up with over-correction which causes an oscillation.  The antistall gain kicks in if the RPM drops 150rpm below the idle target.  Your idle gains are quite high compared to what is typical for E-throttle, although I suspect your odd setup with a linkage and small butterfly in the mix probably means the usual rules dont apply.  Typical proportional gain is 1-2 and about 2-3 for the anti-stall.  I have never really noticed the anti-stall to have a lot of affect.   

[SchuKingR]

just wanted to give an update. I think with a 4% E-throttle up to 2000rpm and proportional gain at 3 and anti-stall at 5 it looks really promissing. Now I'm fighting some new errors, that I did'nt had before. First was E-throttle minDC fault. Fixed that by giving it 5% more DC. Now I have a TP main/sub error...

To calibrate TP main and sub, I turned off the E-throttle actuator and manually closed and opened the throttle and wrote down the voltages like I read in another thread with the S54 actuator, because auto calibration didn't work.

Today I did log my drive home and now updated the TP main and sub open and closed voltages as experienced in the log with throttle fully open and fully closed while driving. Is this the right thing to do or is there another better way?

 

Edit: just took a look at the G4X software. there a whole lot more for the idle/e-throttle stuff. I think I need a G5 to replace my G4+ Thunder release date?

[SchuKingR]

I have another log from today morning. One TP error at 5:29 and one minDC error at 15:46. Don't know why the minDC keeps getting lower and lower, but I fix this by adding another 5%.

I don't have any idea how to fix the TP error... can someone please help me or guide in the right direction?

Log: https://drive.google.com/file/d/154ohzquwaVrVoqAG0CtQolriRRFXnGJH/view?usp=share_link

FD3S_Thunder_MAP_V60.pclr

[Adamw]

The TP error is because the relationship between your TP Main and Sub is not repeatable.  It seems worst around 20-30%TP.  If you have one sensor on the motor and one on the throttle body this will be your issue, the linkage is changing ratio around there somewhere.  You will really need to fit a dual track senor on the throttle body.  

The Min DC error is because you are commanding 0% TP in the target table, so the throttle will be sitting on the mechanical stop, if the motor has been sitting on max/min DC for more than 3s without moving then the ecu assumes the throttle has jammed so switches to safety mode.  Set the smallest value in your E-throttle target table to 1% and that will solve it (usually you have the same idle % all the way across the top row).  

[SchuKingR]

Okay thanks for the explaination 

I'm using the dual track sensor from the OEM mazda throttlebody. So the linkage shouldn't be the problem... maybe the sensor is dying. I try to source another one. 

I will change e-throttle target as well. Once again thank you very much!

[Pete_89t2]

10 hours ago, SchuKingR said:

Okay thanks for the explaination 

I'm using the dual track sensor from the OEM mazda throttlebody. So the linkage shouldn't be the problem... maybe the sensor is dying. I try to source another one. 

I will change e-throttle target as well. Once again thank you very much!

Are you using the OEM FD TPS sensor? I see from the FD factory shop manual (FSM)/wiring diagram that it is indeed a dual track sensor, and you're correct that it is directly linked to the OEM throttle body, so the linkage isn't your problem here. That said, I'm not certain if both tracks of the FD's dual TPS sensor mechanically track the full range of throttle motion - the FSM refers to one of these as a "partial" and the other as "full" range, but doesn't give much more detail. This is similar to the TPS in the series 5 FC, where one tracks full range of throttle motion, and the other would only tracks partial motion, like the first 1/4~1/3 throttle opening. If that's the case, you'll need to somehow rig up a dual TPS sensor that can mechanically "see" the full range motion of the throttle.

[SchuKingR]

Yes. One sees the full range and one only like 40% or so. In the tps settings there is a setup for this. So the ecu knows that. 

I will try to use my old voltage values from before I converted to E-throttle and see if this works. Normally it should work, because i never had any errors with the mechanical setup. 

I forgot that I have this values.

[SchuKingR]

Just wanted to share that I hopefully solved my problem. The auto tps calibration could not work, because there is a point, where the single lower throttle blade actuation switches to drive the upper two with it. At this point, the auto tps calibration thought, that the throttle is jammed, because of the more force needed to actuate the other two blades. So I started the auto tps calibration and gave the actuator a little helping push at that point. 

So now only TPS main/sub calibration could not be finished, because it was at that point again. But I had the min and max voltages now, so I manually gave it more and more throttle until sub was at 100% and wrote the main % down.

After all of that I did a 20km test drive without any issues

[SchuKingR]

On 4/19/2023 at 2:42 PM, SchuKingR said:

Okay thanks for the explaination 

I'm using the dual track sensor from the OEM mazda throttlebody. So the linkage shouldn't be the problem... maybe the sensor is dying. I try to source another one. 

I will change e-throttle target as well. Once again thank you very much!

had the error at longer drives again. Changed to a contactless sensor then. Works flawless until now.