304 running on 808 in ski boat - idle surge

Holden Delco ECU and PCM Tuning
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304 running on 808 in ski boat - idle surge

Postby rhys_main » Tue Nov 14, 2017 6:53 pm

Hi all,

Been reading through this forum with great interest for a while, really great information!

Been working on the tune for my ski boat recently and have an issue that I can't quite figure out... The surge/stumble at idle when out of gear.

Few details about the setup:
- Running an 808 with 12P (eeprom - so no live tuning)
- Modified the 808 for high speed logging
- 4 wire narrow band O2 sensor
- Running a knock sensor with V8 knock board
- Engine is raw water cooled with a thermostat (means operating coolant temp is about 65-75 degrees)
...Lake water is pumped through the engine, exhaust manifold jackets and then dumped into the exhausts about 150mm downwind of the O2 sensor.
- Cam - DUR@50 209/209, V/LIFT 448/448 (nothing crazy)
- Dog clutch

It runs well cruising and it's pretty good at idle with the dog clutch engaged (idling forward). It's not very happy at idle without a load on it.
The revs fluctuate increasingly until it reaches limit where revs drop greatly, at that point the IAC catches it, it revs up and the cycle starts again. This is about a 5 second loop.

I've tinkered with a few different iac settings and idle spark control without much success...
I'm now starting to think that its running lean at idle... the O2 signal looks way too lean to be corresponding with the AFR demanded.
I can only experiment during certain weekend with the boat on the water, so I'm trying to get a rounded idea of the different factors that I should be looking at.
The fact that it idles better in gear than without any load on it makes me think that the issue only starts up at MAP values lower than 40 kPa... but unsure

If anyone has any thoughts, hints or tips on the matter it would be VERY MUCH appreciated.
As you can imagine, having a rock solid idle is a HUGE benefit for a boat, I'd also LOVE to get the idle RPM as low as possible to slow the forward motion at idle right down.

Apologies for the long winded message, just wanted to try and give the best description I could.

I've attached the BIN and log file; below is a timeline of what was going on during the logging time:
0-0:50- Idle out of gear
0:50-1:50- Idle in gear
1:50-6:20- Light cruise in gear (lean cruise engages at 4:20) -- still pondering whether I should disable LC
6:20-6:52- Idle in gear
6:52-8:15- Idle out of gear (best section to get an idea of the surging)
Attachments
3075.JPG
3075.JPG (112.13 KiB) Viewed 117 times
2.0 light cruise.xdl
(347.52 KiB) Downloaded 2 times
2.0 Boat.BIN
(32 KiB) Downloaded 2 times

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Location: Pine mountain .vic

Re: 304 running on 808 in ski boat - idle surge

Postby jenko » Tue Nov 14, 2017 7:10 pm

where are you located I may be able to help ,can you run it with hose hooked up?
can't read your XDL file.have posted bin from my boat you might want to look at idle afr and set them to around 14.7 at running temp plus check out a few temp related running variables and set up to your running temp . Don't copy my Fuel and timing tables as they are for V12 jag but rest is valid.
Also post pic of where is the oxy sensor mounted.
Attachments
good safe boat tune 01-04-17.bin
(32 KiB) Downloaded 1 time

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Re: 304 running on 808 in ski boat - idle surge

Postby Dylan » Tue Nov 14, 2017 7:58 pm

Do you have a wideband you can use?

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Joined: Wed Apr 26, 2017 9:50 pm

Re: 304 running on 808 in ski boat - idle surge

Postby rhys_main » Tue Nov 14, 2017 8:19 pm

Thanks for the quick responses!
Hmm... Is there another accompanying file that I need to include with the XDL? I'm using the "OSE_$12PV112_1BAR - Petrol.adx" definition file for OSE 12P V112.

I'm located in Melbourne, unfortunately I keep the boat near Eildon so really only work on it on certain weekends.
Yes I can run in on the hose, depending on how things progress I might bring it back to Melbourne to to keep working on it.

Thanks very much for posting your bin file, I'll check it out.
I don't currently have a wideband... perhaps that's something I'll have to look at.
I was hoping that its something relatively simple, hoping I can at least move things in the right direction to begin. I understand that accuracy is limited without a wideband.

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Joined: Wed Apr 26, 2017 9:50 pm

Re: 304 running on 808 in ski boat - idle surge

Postby rhys_main » Tue Nov 14, 2017 8:46 pm

Here is a pic of the O2 sensor location.
Tapped into the water cooled elbows up near the connection to the exhaust manifold.
The 90deg brass fitting was installed into the water dump hole in order to direct the water away from the sensor. Prior to installing the brass fitting I had issues with spray hitting the sensor.
I know it's not ideal, but it really it the best option with this type of setup.
While running the O2 output is as expected, I don't have much reason not to trust it from what I'm seeing.
Currently the idle conditions are not calling 14.7, so I don't believe the O2 sensor is contributing to the surge.
My long term plan is to only enable closed loop for cruise/skiing RPMs where exhaust flow and clear exhaust tips ensure the sensor is delivering relevant data.
Attachments
IMG_3416.JPG

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Re: 304 running on 808 in ski boat - idle surge

Postby jenko » Tue Nov 14, 2017 10:39 pm

surging idle is usually caused by lean idle mixtures I actually widened the range at which it goes into closed loop rich and lean threshhold
closed loop min temp threshold
ve learn temp threshold
to list a few
have a look at my idle spark parameters as I spent a lot of time tweaking them to hold a steady idle ( i don't run an iac)
I also tried incresing idle spark timing as map increased but worked better as a constant 28 deg and the idle spark parameter settings take out around 5 deg and add timing if revs fall bellow idle threshold
I am running 14.7 across the board to 75 kpa , not much benefit running richer, O2 sensors like it leaner
I use about 20 litres of fuel for an average days skiing with learners as it would always be in closed loop

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Re: 304 running on 808 in ski boat - idle surge

Postby Dylan » Wed Nov 15, 2017 1:27 am

Idle timing make's a big difference. The 304's like 28 degrees in general. Also it helps I find to minimise the time delay for closed loop idle. Usually 2-5 seconds is enough.

Ad the idle proportional spark cut that back to maybe 2 degrees or less.

Contact Biggvl on here and get a Spartan 2 wideband and NVRAM. You won't regret it.

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Posts: 342
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Location: Pine mountain .vic

Re: 304 running on 808 in ski boat - idle surge

Postby jenko » Wed Nov 15, 2017 7:14 am

Contact Biggvl on here and get a Spartan 2 wideband and NVRAM. You won't regret it.

second that

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Re: 304 running on 808 in ski boat - idle surge

Postby rhys_main » Wed Nov 15, 2017 10:48 am

The thing that I'm struggling to get my head around is what the difference is between this setup and its standard place in a car.
Even running an untouched bin results in surge at idle... I'm guessing its a result of less "bolt-on" loads such as power steering pump etc.
Is there a flag or similar in 12P that defines manual/automatic transmissions? I'm yet to find it if there is. The data flow reports transmission as automatic... not sure if that could be contributing?

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Re: 304 running on 808 in ski boat - idle surge

Postby Dylan » Wed Nov 15, 2017 11:07 am

No it's in the wiring maybe worth a look into

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