E38 PCM tuning experiences to share....

[Redline Motorsports]

How does the B1977/B1978 get understood? How do Mv correlate to the knock sensor function?

Howard

[RonC]

How does the B1977/B1978 get understood? How do Mv correlate to the knock sensor function?

Howard

I'm not sure how it does but that was the only thing I could change that would reduce the excessive KR to let the timing come up to 27 degrees. I still don't know how it gets to 27 as my base timing is now set to 18 degrees from .72 grams per/cyl on up . I can't log anything that is "adding" to the base spark, but it works for now. That was before I realized I could log the individual cylinders for the KR, but I will try that later on when I have time to fine tune it some more.

Ron

[ntae]

hey there ntae, you couldn't post up that tune file could you. It would be interesting to see that calibration changes between the base model and the HSV model.

Cheers,

Mike

http://www.ntautoelectrics.com.au/tunefiles/


if any one has any holden e38 ecm .tun file email them to admin@ntautoelectrics.com.au and i will host them for every one to down load

[GMPX]

How does the B1977/B1978 get understood? How do Mv correlate to the knock sensor function?

Howard

Basically the knock sensor filtering needs to remove the noise that might be considered knock. The mV relates to the voltage signals from the knock sensors. If you are a musician you might know what a noise gate is?, same thing here.

Cheers,
Ross

[The Alchemist]

oh good that worked ok
Had to post it up then check.....
20% torque increase overall, mixtures leaned out on their own once the timing improved, tweaked them to 12.5:1 after that.
Good old burst knock had to be neutered as it was pulled timing by 3 deg at 5300rpm killing the top end.
I set timing in low octane map to 2 degrees under best tolerated timing so nice and safe then added 6 deg and pasted that into high octane table > should be enough I think. Also tweaked Octane scalar increment rate so it learns upward a bit quicker.
Thats about it for an afternoons work

Comments welcome.....

Mike

PS: these things will be wicked once we stick a cam up them

[Delco]

oh good that worked ok
Had to post it up then check.....
20% torque increase overall, mixtures leaned out on their own once the timing improved, tweaked them to 12.5:1 after that.
Good old burst knock had to be neutered as it was pulled timing by 3 deg at 5300rpm killing the top end.
I set timing in low octane map to 2 degrees under best tolerated timing so nice and safe then added 6 deg and pasted that into high octane table > should be enough I think. Also tweaked Octane scalar increment rate so it learns upward a bit quicker.
Thats about it for an afternoons work

Comments welcome.....

Mike

PS: these things will be wicked once we stick a cam up them

???? let me get this straight in my head , you set the low octane table to be 2 deg under MBT then set the high octane table to be 4 deg above MBT.

So in effect you are running the engine in knock at all times ?

Normally with the 6L we take timing out of the stock timing tables to get MBT and make power.

These engines are very timing sensitive being higher compression than the LS1 and different combustion chamber and intake port.

They are responding well to cams / displacement increase and superchargers , bit trickier to tune than the older stuff but once you have a handle on it things sort of flow into place.

[The Alchemist]

hi there Delco,
considering that the car now actually accelerates when you put your foot down I think that the results speak for themselves. I spent most of my time getting out the wrinkles so to speak in the factory tune.

I have set the low octane table below MBT, remember the engine was running 91, with the theory that if it knocks then the octane scalar system will pull it down well past knock threshold. I allowed 4 degrees above MBT for the high octane table because we only have 91 & 96 here and I thought that 4 degrees would be plenty allowing for the odd tank of 98 if you went out of town.
The factory tune runs a spread of 10 degrees (as you would be aware)and my new low octane table is set much lower than the factory low octane table and is of a better match for what the engine wants.

Also with the factory tune the Flashscan was constantly registering "knock" and the octane scalar was ramped around to "1" all the time and still knocking under load > too advanced I believe and to quote you...

"So in effect you are running the engine in knock at all times ?" > was this Holdens intention as well.....?

Now the Flashscan logs little or no knock at all and produced the dyno graph you saw earlier.

If this is not the correct way to do it or yoou have some other advice to share please let me know as this is the first one I have tuned.

"Thought I was doing ok actually and only trying to pass on information"

Thanks,

Mike

[Delco]

Ideally the engine should never see knock , knock happens when you are past MBT , any knock can be detrimental to the engine which is one of the reasons GM made the knock sensitivity table so sensitive , Holden then retuned and though incorrectly that they could run more timing than they do.

The factory doesnt always get it right , having worked in a engine development enviroment for companys such as this you soon learn that quite often they dont get it right.

You would be suprised at the amount of power that can be picked up on a dyno by removing timng at critical points in the spark table.

The new knock pids are awesome as you can monitor the knock sensitive cylinder ( yes some are more sensitive than others ) and tune accordingly.

I didnt see that you were using average fuel , but really you should tune to the fuel you use 90% of the time .

[The Alchemist]

Ideally the engine should never see knock , knock happens when you are past MBT , any knock can be detrimental to the engine which is one of the reasons GM made the knock sensitivity table so sensitive , Holden then retuned and though incorrectly that they could run more timing than they do.

The factory doesnt always get it right , having worked in a engine development enviroment for companys such as this you soon learn that quite often they dont get it right.

You would be suprised at the amount of power that can be picked up on a dyno by removing timng at critical points in the spark table.

The new knock pids are awesome as you can monitor the knock sensitive cylinder ( yes some are more sensitive than others ) and tune accordingly.

I didnt see that you were using average fuel , but really you should tune to the fuel you use 90% of the time .

Yeah our fuel here is crap quite honestly and the dealer told him you can run it on 91 or 96 ....
So would Holden or GM have set the individual Knock sensitivities per cylinder tables on an engine dyno in a controlled environment etc.......at all table points g/s rpm etc and why is Cylinder B set so sensitive compared to the rest. It was triggering knock retard at 13 degrees at 3000rpm at full load during a run. I am now running 17 degrees in the same spot with zero knock and 20% more torque. Surely that 1 cylinder can't be that far out from the others > what do you think?

Mike

[Delco]

Back passenger side cylinder is very sensitive to knock , more so than the others.

It is also the first cylinder to break normally.

4600 -5200 is where the engine has the most tendancy to knoc as well