VEMS : revs rpm dropping off when engine loaded

[QuattroFever]

ok, had to go for a blast to cheer me up and managed to dial out my surge which im pretty happy about. :mischeif:

It seems that maybe the heat has something to do with it. After a motorway cruise pulling in a garage here and there ive noticed its not as bad. Not dropping off if i press the clutch in on the move.

Still drops a little if you blip it under load. Its a little shaky and idling a little higher than it was in tescos when it was stable. Speedo reads 1150 and vems shows 950-1050. I can live with that!

ISV is in wagner location, felt very hot to the touch when i checked the oil.

Feels like a productive eve. Have to see how she behaves in the morn/next traffic jam.

Thanks to all for the help!!!

[A80Avant]

set the kpa value for fuel cut to zero in case you have a value there. That is also under the settings for the fuel cut/resume.

that cured my stall when going on neutral. However the PID in my opinion will not work well that way.

is your ISV located in the normal area that Wagner manifold uses?

[A80Avant]

mine was doing something similar when the D was that high.

[Reidar]

pleas share a config or logfile, so we can have a look at it

[QuattroFever]

aaaaaaaaaaargh! This is driving me insane!
You think you've got it nailed and then it does something random.

Been at it since 7.30 blipping the throttle in tesco. Even the trip computer was flashing 2:00 at me an hour ago telling me to quit.

P - 10
I - 20
D - 170

Integ. Decr. - 5
Integ. Incr. - 35

Was great! Shut it off, checked oil ready for a run, started back up and its bouncing up to 1400 then down to 900
Wtf is with this?

[ranz]

dropping off on the overrun.
It idles ok but when you rev it and go to pull away its dropping below to about 500rpm and stumbling three times then pops back up to idle speed with hardly any oscillation once it recovers.

I had same problem and only thing that helped was to rais D to over 150, on my own car I used 170.

[QuattroFever]

a log would help. Will get one up.

[QuattroFever]

this is different. You mean when the fan cuts in and the idle speed drops. Mine is dropping off on the overrun.
It idles ok but when you rev it and go to pull away its dropping below to about 500rpm and stumbling three times then pops back up to idle speed with hardly any oscillation once it recovers.

Afr goes lean -> 18.9 as it comes down from rpm. Whether you blip the throttle, coasting to a stop, suddenly press the clutch etc.

Fuelcut shouldnt be active but its the kind of symptom youd expect if it was.

[prj]

By the way, you will always see some drop on the revs under load,hell that happens with motronic as well.

Yup, it does.
Motronic regulates idle using ignition and the ISV. Smaller changes are "caught" using ignition until the ISV catches up. On larger changes, such as the AC, it'll dip a bit, because an ignition adjustment won't be enough and ISV reaction is not instant.

[A80Avant]

By the way, you will always see some drop on the revs under load,hell that happens with motronic as well. The idea is for it not to stall. Mine now drops to 900ish under full electric load, and it never plummits.

[A80Avant]

I agree with you Reidar! It's funny how so many cars with similar equipment can have so different settings and yet work!. I think there are variables that each one of us take for granted but have an effect in idle, which is why there are differences.

On D 150 ranz, my idle was fine once I switched the engine on, but once I slipped the throttle, the idle never came back to 950rpm, but stayed at 1200. I have read about PID tuning and that was to be expected. So for that value to work for you, you must have had some other different settings to mine.

[Reidar]

A80Avant:
I dont say that older FW`s got issues with idle, i just say that you cant expect my configs to work with different versions. Cause there ARE differences on some FW versions.
These PID settings are quite extreme yes, and dont look much like my usual settings, but it should defenetly do something to his idle. I even got this working quite good with a car running AC, and aprox 60rpm drop in idle when ac on.

I use the ignition adv. as a measurement to see how much my refDC is off, cause it`s sometimes hard to just set it right te first time and have the car idle perfect. I switch on and off the ignition adv. to see for changes. In my opinion, if the ing.adv is off after you have changed your refDC, it`s trying to compansate for something, and usually that is the redDC. atleast if the other settings are correct

I have noticed that heatsoaking the MAT allso gives issues at idle and temp changes. EGO ON, usually fix these problems, but some car`s dont use a WBO2 even tho I recomend it. then changes to the mat/tps fuel table is needed at 0% trottle.

ranz: I belive you And yes! two different car`s often need totaly different settings. I dont think I got one config with the same idle settings, and i probably got atleast 50 configs from different cars, or cars witch have been modified since my first config.

[ranz]

I tried your 150 setting once and didn't work. Ad I said, now I'm still on 1.1.81 and my D value is 2.

Just for information, what your cars idle made with 150 D? did not idle correctly, did not catch idle, or when the vent/heater where turned on and it dropped? or something else?

[A80Avant]

You cannot say that PID settings are right or wrong unless you see the idle as a whole. I know that we have discussed this before but then I had a talk with Matthias and another bend developer who explained to me the things I am suggesting above. It may be that by using previously so high D value you could have reached a level of inactivity it noise of the PID system that it made it work. Who knows. I tried your 150 setting once and didn't work. Ad I said, now I'm still on 1.1.81 and my D value is 2.

[ranz]

may i say that reidar has a nice explanation there BUT i have to say this to people who think that previous firmwares have had problems with idle. I dont believe it.

i am still on 1.1.81 and my idle is responding to changes nicely. I use much smaller values on the PID (something like 20/12/2) and much larger on integral limits and that allows the PID to make big changes if needed but slower!!!!

You may or may not belive it, but we discussed it on another topic where I played with my idle settings and I DID NOT get stedy idle unless I raised D over 150. I tryed many tutorials how to set idle correctly etc. etc. etc. ended up pretty much on same spot.
Now last week I chaged FW, the settings stayed the same (D: 170) and it worked well, but yesterday I connected shift light, launch and shift cut and because of that topic I also tried what idle does when I turn on air vent, lights and rear widow heater, the idle was not dropping below 800 (it's set to 850)... also I tried lower the D to 2, to 5, to 10 and ended with 9 because now it works with that also with previous FW with that low D the RPM dropped down to 600 and then catched the preffered 850 when revs come down.
So, the FW is important here! also, cars with similar setup (lets say original setup) also need different settings, two similar cars do not work well with same settings.