$EE LT1 Cylinder Balance fueling trims

After lowering the idle timing and main Idle timing table, I did as few Cylinder drop tests with EEHack.
Changing the timing makes changes in the BLM splits anywhere from 5-10 points either way so it obviously makes a difference on fueling depending on what the timing is.

CYLDROP Memo ::
(Higher is better...)
CYL1=26.5 CYL2=27.3
CYL3=26.5 CYL4=27.7
CYL5=27.8 CYL6=29.9
CYL7=32.2 CYL8=31.3
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CYLDROP Memo ::
(Higher is better...)
CYL1=23.4 CYL2=25.2
CYL3=24.7 CYL4=25.3
CYL5=25.1 CYL6=27.4
CYL7=29.5 CYL8=28.7
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CYLDROP Memo ::
(Higher is better...)
CYL1=24.2 CYL2=25.9
CYL3=26.0 CYL4=25.4
CYL5=26.2 CYL6=28.0
CYL7=29.3 CYL8=29.2
------------------
CYLDROP Memo ::
(Higher is better...)
CYL1=23.7 CYL2=23.7
CYL3=23.5 CYL4=23.3
CYL5=23.5 CYL6=26.0
CYL7=27.2 CYL8=25.2
------------------
CYLDROP Memo ::
(Higher is better...)
CYL1=23.5 CYL2=26.7
CYL3=24.8 CYL4=26.5
CYL5=26.2 CYL6=28.3
CYL7=29.2 CYL8=29.9
------------------
The previous adjustment method was to use an IR temp gun which I've found unsatifactory as the middle 2 cylinders always run much hotter than the corners.

I've tried disabling individual cylinders but the BLM's just max out and O2's just flatline.
I've seen Kur4o's updates to alter the individual cylinder trims live but wondered how you'd measure the changes?

Keep doing cylinder drop tests or would raising the BLM ceiling allow the differences to be monitored.

Thoughts anyone

Mitch

you're never going to balance 8 cylinders with 2 narrowband sensors, you need to do it by temperature, monitoring vacuum fluctuations, or by feel.

when trying to balance your cylinder fueling, first you need to accept that you will never balance fueling perfectly in a shared manifold situation, because you will never get consistent airflow balance. even if you do manage to get everything to line up, add 20 rpm or a bit of heat and it'll go to hell again.

if this is important, start planning individual throttle bodies

eehack's cylinder drop test uses both RPM and MAP for its measurements. i'm not sure it's accurate enough to balance cylinder fueling, it's mostly for detecting non-firing cylinders.

Do you think measuring the time between TDC signals from the opti for each cylinder would be useful - say to 16us precision? It's one of the items on my DIY-LTCC todo list, specifically for this purpose. I've also been thinking about the possibility of plotting angular velocity using the high resolution signal if the mcu is fast enough to handle it.

Mitch - you wouldn't need to be using it as the ignition system, it could be plugged in between the opti and PCM at the 4 pin connector on the side of the intake.

Quote:

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Originally Posted by steveo

you're never going to balance 8 cylinders with 2 narrowband sensors, you need to do it by temperature, monitoring vacuum fluctuations, or by feel.

when trying to balance your cylinder fueling, first you need to accept that you will never balance fueling perfectly in a shared manifold situation, because you will never get consistent airflow balance. even if you do manage to get everything to line up, add 20 rpm or a bit of heat and it'll go to hell again.

if this is important, start planning individual throttle bodies

eehack's cylinder drop test uses both RPM and MAP for its measurements. i'm not sure it's accurate enough to balance cylinder fueling, it's mostly for detecting non-firing cylinders.

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Has anyone actually had success with measuring and equalizing temps?
As the timing affects the fueling and feedback by the O2's I don't really know where the issue lies.
The cam motor is much smoother with lots of idle timing (it's probably fighting itself but map is lower and the car has much more throttle response.
With timing dropped it's lopier but struggled to break the tyres loose in 2nd.

I can see bigger oscillations in the map now.
Is this caused by the cam affecting the vacuum or a symptom of the fueling being off?

I don't know !
Mitch

Quote:

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Originally Posted by spfautsch

Do you think measuring the time between TDC signals from the opti for each cylinder would be useful - say to 16us precision? It's one of the items on my DIY-LTCC todo list, specifically for this purpose. I've also been thinking about the possibility of plotting angular velocity using the high resolution signal if the mcu is fast enough to handle it.

Mitch - you wouldn't need to be using it as the ignition system, it could be plugged in between the opti and PCM at the 4 pin connector on the side of the intake.

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Hi
Erm no Idea on that one sorry.
It was why I asked about the Cylinder Id recently.
IF you could id the cylinder you could monitor the changes.
Who'd build a system where you can id half the cylinders or one of the other 4??

The PCM does give a delta in rpm value as a percentage iirc.
What would angular velocity give you ?
Can you see and monitor every cylinder to track changes?
At least then you could even the differences between cylinders out some.

Mitch

My initial question was generally posed to steveo. The diy-ltcc controller is tracking cylinder # and time between tdc signals. Creating a function to dump all 8 cylinder's 90 degree times to the serial data would be trivial. Tracking angular velocity between tdc signals is (at least as I understand it) how obd2 ecms detect individual cylinder misfires.

The cylinder id will only let you identify cylinders 1, 4, 6 and 7, and you'd need to extrapolate the others without indexed low res triggers. But the I believe the aldl data is going to be too slow to give useful information on individual cylinders. I've never noticed an rpm delta pid, will have to dig that one up and see what your'e talking about.

Quote:

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With timing dropped it's lopier but struggled to break the tyres loose in 2nd.

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that's why timing advance for closed TPS is in a different table. no load and lots of load are quite different operating conditions. one shouldn't affect the other...?

Quote:

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Has anyone actually had success with measuring and equalizing temps?

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to the extent where it was barely running on several cylinders, and after 'equalizing' it was running on all of them, yes.

again, balancing fueling in such a manifold is a bit crazy, there's tons of fuel being flung around in the manifold, you really can't control it precisely.

Quote:

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Originally Posted by spfautsch

My initial question was generally posed to steveo. The diy-ltcc controller is tracking cylinder # and time between tdc signals. Creating a function to dump all 8 cylinder's 90 degree times to the serial data would be trivial. Tracking angular velocity between tdc signals is (at least as I understand it) how obd2 ecms detect individual cylinder misfires.

The cylinder id will only let you identify cylinders 1, 4, 6 and 7, and you'd need to extrapolate the others without indexed low res triggers. But the I believe the aldl data is going to be too slow to give useful information on individual cylinders. I've never noticed an rpm delta pid, will have to dig that one up and see what your'e talking about.

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There's an rpm variation in EEHack