(Toyota Altezza) Car jerking at low rpm

[Jappachino]

Hi, I'm experiencing some odd issues with my car right now where the car jerks when I am at low-ish RPM's (1200-1600ish)

My log and current tune attached:

https://drive.google.com/drive/folders/1BA6GsKF4p1TDm9g5rqUjZCqe9HfGap90?usp=sharing

At around 5:20 you see a slight case of it doing the odd RPM jerk, and it was ESPECIALLY bad at around 6:50, the car jerks so hard that it moves my body and makes me hit the throttle a bit too... I noticed a few things:

- My lambda is hitting OVER 2.0 at certain times... Should I refrain from driving the car in this state??

- I had the car parked for way longer than anticipated to figure out some idling issues, and I have ~4 month old fuel and I am trying to burn it off by driving around town at low RPM's (under 4,000)... Would the old fuel be a cause of this??

- I was talking to a person I got to know who has a VERY modified turbo Altezza helping me figure out the idle issues (My car is N/A, very mild modifications). Taking reference from his tune, I changed the idle ignition MINIMUM clamp to 5 degrees BTDC instead of the 0 degrees I had on my original tune which had the unstable idle. Could this also be the culprit?

Thanks!

[Adamw]

Looks like overrun fuel cut is a bit too abrupt and the pedal to throttle relationship is a bit steep off idle and some of the idle settings are a bit odd.  I have made a few changes in your map attached, give it a try and do us a new log.  It may not be much better yet but a few tweaks from the next log will probably be better. 

You can use the compare function to see what I changed.  

Try this 1.pclx

[Jappachino]

Oh one thing @Adamw, I'm sure you noticed that my e-throttle range is set from 2% to 98%... I was talking to a few Altezza owners and they suggested doing this, as the teeth of the e-throttle's internal gears get shredded off when it slams into each end of the stops. Did this affect it by any chance? 

One of the guys I was talking to had a Beams swapped vehicle running on a link G4x. He set his e-throttle's clutch system up to a GP PWM table instead of a flat frequency as below:

 

He told me that the Toyota e-throttle clutch system works at 500Hz and he basically made it so that at 0% and 100%, the magnetic clutch is JUST strong enough to open and close the plate, but will allow a little bit of slip if it slams into the stops, saving the internal gears which I've shredded off in 2 throttle bodies.

I tried setting this up in my tune too, if you look in auxiliary outputs > GP output > GP PWM 1 and set the output to Aux 7, the table is there. However when I do this, my G4x tells me that the e-throttle is setup incorrectly and the e-throttle is disabled... How do I go about having this work?

[Adamw]

E-throttle target should be zero for idle in G4X.  Note 0% will never actually be commanded since the idle base position value is added to the target (so the least the throttle will ever be closed is 1.8% using this map).  

[Jappachino]

Ok here are two logs of just city driving. Idling is much better, I think it's basically there. Logs here:

https://drive.google.com/drive/folders/1FFxAHQKNQPAD38ZqWClTYjIivi197f74?usp=sharing

One thing I had to tweak was the RPM lockout, having it at 400 made the revs just hold when I blipped it at idle... I reset it to the 1100RPM I had it at and the car seems happy, no undershoots when clutching out for a stop. Also this may be a really dumb question, is it normal for my lambda to occasionally spike to 1.2-1.6 while driving? I noticed my car always did that, I just wanted to double check that my lambda values look normal to you.

 

[Jappachino]

Aaand just as I sent that and hopped into my car for a quick drive, my idle started undershooting when I clutch out.  I will try to log that later tonight when I am back in the car.

[Adamw]

RPM lockout needs to be around 4-500 otherwise it will close the throttle when coasting and stall or undershoot when you clutch in.  

Try the map below with the base position closer it will hopefully stop the rev hang.  

For the undershoot after a blip you need to play with the dashpot offset/hold/decay.  I have given it a little more in the attached map.  

Try this 2.pclx

[Jappachino]

Tired your 2nd tune, I felt like the rev hang is still the same but now the idle undershoots off-clutch, and now going back on throttle is a bit lazy when upshifting? It was a pretty short drive, but log here:

https://drive.google.com/file/d/1KyKGBqnsTElTV07iZXP-Th5Njg2hUXak/view?usp=sharing

[Jappachino]

OK I finally drove around town enough that I got my fuel light to come on, and tossed in a full tank of high octane (pump) gas! Here's the log of a bit more spirited night time drive:

https://drive.google.com/file/d/1X7DUmYTSHUCELXaFF5Vh0azhLgU753n7/view?usp=sharing

What I noticed:

- At the beginning, I blip the throttle and the RPM drops way below target (~600RPM) then comes back up. What would be the rough procedure of tweaking the dashpot, is there a certain order of the values I tweak to get a good result?

- When I'm off throttle, I noticed there is a lot of popping and subtle burbling going on, is that normal?

- There definitely is an undershoot of the RPM's when I clutch in at some lights, I noticed this happens when I clutch in early after seeing the light turn red ahead of me. If I keep the clutch engaged until I'm almost stopped, the undershoot happens less. Is this just a driving style I need to adapt?

- At the VERY end you can see the idle RPM got stuck at around 1400RPM when I stopped after parking, and I had to blip the throttle to get it back down. What would be the culprit of this?

Thanks in advance.

[Adamw]

Something a bit odd going on with the required throttle position to achieve the correct idle speed not being very repeatable.  For example at the beginning of the log it needs 2.1% throttle to idle at 900RPM, at the end of the log it only needs 1.1%TP to idle at 900RPM.  Temp is the same at both points, no fans or AC on, MAP is very similar suggesting air flow is the same.  So at the beginning of the log the 1.8% base position is a bit low so you get the undershoot.  At the end of the log the 1.8% base position too high so the RPM settles above the lockout and hangs.  So it almost seems like there is possibly some backlash between the TPS sensor and the throttle shaft?  

I dont know these throttles well but it might pay to pull the TPS off and see if you can find a cause.  Im not sure if the TPS is spring loaded or not on these.  On some nissans that dont have a spring loaded TPS you can see this backlash and a blob of silcone in the TPS before assembly solves it.  Otherwise possibly it is not mechanical backlash but the TPS is a bit worn in the resistance track around idle position and is giving a variable idle voltage.     

[Jappachino]

57 minutes ago, Adamw said:

Im not sure if the TPS is spring loaded or not on these.

Yeah these TPS's are spring loaded, but when I uninstalled the factory tps for the new one it didn't have any grease on it as far as I could tell... The TPS is brand new though. Maybe I will try tweaking the position of the tps sensor and recalibrate.

Is there something on the ignition control side acting up causing this?

[Adamw]

No, ign is sitting on target in both examples.