Idle issue on Vems.

[popdemonic]

Actually,this's not really issue since I'm running on VEMS

Pretty nicely.After replaced the new N80 valve,it fixed the

Oscillation idle,unstabilzed on Lambda.now I can get my Idle

at 900rpm.the only problem is sometime the when I'm driving

and keep down the clutch pedal,the idle drops down to 700rpm

occasionally.definitely,it's not swing back to 900rpm.I need to

Rev the engine up and then it's just back to 900rpm.

I set the PID,integral decrease,increase limit by this order..

P=20
I=3
D=50(tweak up 150 not much difference)

Int dec. Limit=50
Int inc. Limit=50

I'd say most of the time,the idle is doing its jobs
goos.I just feel like I can get the idle better.

It's very annoyed to see sometime the idle stick at
600-700rpm and won't be back to 900rpm until
I need to rev up once so it's stabilIzed at 900rpm
again.

Could this be the ign. Timing related?I never had
Oscillating idle after n80 valve had been in.

My friend told me to add more number on the "P"
to let the VEMS stabilized and catch up the low
Idle better.

Another problem is I set the overrun fuel cut

At 1700Rpm and activate 1600RPM.at the low gear

Let's say on 1 or 2 gear.once I let off gas ,when

The rpm drops down and passing through 1700-1600rpm.

just like the car stalled(slightly jerking).rev needle

swing up and down a bit while passing 1700-1600rpm.

I'm thinking to set the overrun fuel cut at higher RPM

at 2000RPM.would this help the engine stalled issue?

[QuattroFever]

what firmware and what intake mods you have?

[prj]

Overrun fuel cut is not the problem, if idle does not pick back up.
Sounds timing related to me, you should add more timing at lower revs.

Say about 15 degrees at 700 rpm, and then slowly decreasing towards your idle set point.
I am not very familiar with tuning idle on vems, so I can't tell you exactly what to modify, but the idea is to have a timing reserve at your target idle speed, so that it can be advanced (fast path) before the ISV (slow path) reacts.

Does VEMS have a duty cycle linearization table for idle? That might need bumping. I had the same problem with Vipec and bumping it fixed it, same thing with Motronic on aggressive camshafts.

[QuattroFever]

I have to dial in a lowly 8 degrees at idle speed (alu flywheel) then i have 20 degrees below to give it a kick if it tries to die. This helped it steady.
Also, if you imagine that those bins are points in a graph instead of steps, as the rpm moves along the table it is on a sliding scale, so if you have 8 degrees at idle(900) then 18 in the next bin(1200) when the engine speed goes up by 100-150 rpm the ign could change by ~8 degrees. in other words the bins around your target idle need to be as similar as possible.
HTH.

[popdemonic]

Don't you guy think I might have some hardware issue? I got the low idle at 700rpm when I'm driving
My car out let's say2-3 times.sometime it happens while turning the steering wheel the rpm will be dropping
Once I rev it up,everything is back to normal and solid again.

I'll uploading my log file.please have a look on it mates?

Currently,I'm running on 1.1.95 firmware.i just downgraded from 1.1.96 for the cam sync issue.it seems pretty much improved.

I have Dr.Schrick 260^ Deg. Camshafts on AAN as well.Dunno if this could cause

any effects on tweak the idle?

TIA

Pop

Ps.Dmitri!you got PMs .check your incoming box please!

[popdemonic]

my IGN. Table.



my recent log file.

http://www.4shared.com/file/r4eEe89T/file.html

[popdemonic]

another tables.just in case.

[QuattroFever]

Strange that if you rev it, it will settle in the right place. Have you tried cleaning out isv with carb cleaner or test with another known working to see if the problem changes.

Does it happen when the rad fan comes on?
turn ign. Based idle off when tuning PID.
Also try putting a little more I in i can't read pic v.Clearly on my phone but looks like you have 3 in there. Think i had mine at P:15 I:7 D:40 .

[QuattroFever]

Also i would try and ditch the 8300 column on your ign table and have a column for your idle speed and at least one below. As it is the idle is between two bins. Do the same with VE table.

[prj]

Also i would try and ditch the 8300 column on your ign table and have a column for your idle speed and at least one below. As it is the idle is between two bins. Do the same with VE table.

Also, in the VE, I would say the 200 rpm point is probably not really necessary.
The columns and rows of both tables should be redistributed so that their upper and lower limits are values the ECU actually sees, so you get best possible resolution.
Right now you are wasting a lot of room.

Here is what revs I have in my Motronic software tables for cars on stock oil pump (but keep in mind, in Motronic both the ignition and the fuel tables are 16x16 on 2.2, they are freely resizable though).

600
1000
1280
1680
2200
2600
3000
3520
4000
4400
5000
5600
6120
6600
7000
7400

[prj]

Ignition idle should definitely be used to be able to have a good catching idle, because the ISV is really "lazy" in this regard.
So the way it works is the ECU holds the car with some timing reserve, let's say 8 degrees around the stable idle point, and then the fast path correction is done via going back towards the optimal advance, while the slow path correction is done via the ISV. Then, when the ISV "wakes up", and the target starts to overshoot, the timing angle is retarded back to it's pre-set reserve area and you get a nice, stable idle.

The way to tune it, if you want to use both, is set the advance static to 8 degrees throughout the idle area, then tune the PID on the ISV to work correctly.
After that re-enable the ignition based idle. I am saying 8 degrees, because this is what Motronic uses, and it works well...

This is how I tuned it on vipec, anyhow, and I got a very nice idle.
This is also how Motronic works and gets its idle.

[Jamo]

I'm referring about VEMS here, you don't need both, either or will get the job done. If the integral is working in the negative and the last bin has more ignition advance it works. or as per a4kquattro you can go ignition solely.

[prj]

I'm referring about VEMS here, you don't need both, either or will get the job done. If the integral is working in the negative and the last bin has more ignition advance it works. or as per a4kquattro you can go ignition solely.

What I wrote is not engine management specific. It applies to any engine management system, and I described the algorithm used by most OEM's where a cable based throttle is used.
On ME7 with electronical throttle, still the same system is used, except instead of the ISV there is the response time of the throttle itself. On newer cars without the throttle it is done differently.

Ignition based control is instant, it applies to the next ignition event. Any kind of mechanical means to control the air is not instant, and takes a few engine revolutions in a best case scenario.

So I don't care what your control system is. If you want to have an OEM idle, you do it the OEM way, end of.
"Solely ignition" falls flat on it's face on this engine, when the ambient air temperature fluctuates more than 20 degrees celsius.

[Jamo]

All hail i remove my advice from being a vems user and having set it up on my car, all yours so is the world. pray we never meet

[prj]

All hail i remove my advice from being a vems user and having set it up on my car, all yours so is the world. pray we never meet

I think you are just being stupid now.
Read and understand what I wrote, you are arguing with EFI essentials.

Every single thing I have written is completely true. And you are just talking **** out of spite.
And to add fuel to the fire - where's your awesome setup car? Somehow I have never seen it running right?