Open Loop EE Advice

[spfautsch]

the knock sensor isn't there to prevent you from cracking a piston by making horrible decisions with timing advance; it's to allow low quality fuel to be used while maximizing performance with higher quality fuels. it's not a very good tuning aid, and railing up timing until the knock point is a bad approach to maximize power, imo.

That wasn't my intended methodology. I was seeing a staggering amount of knock so I removed 3+ degrees of timing and it made no difference so I started looking at fueling. I think I might have got into a situation where the more timing I removed the worse it got because it would fall on it's face sooner. Also, see my comment about VE below.

just add timing until it stops making more power (or less vacuum, if we aren't at WOT) and call it a day. this is super easy with eehack's timing skew feature.

That would be easy with someone to do the driving. I think I just had an idea to add to eehack...

Edit: thinking on this, the only way I can imagine it being "easy" is with a driver and a chassis dyno. You're going to be chasing a moving target (MAP). Or am I missing the point? Is this the intended purpose of auto spark?

I ran a bit with a fuel pressure gauge the other day and it looked good to me ~38psi @ idle (45kpa) and ~44psi at WOT. Nice and steady too. Impressive b/c it looks like the original pressure regulator.

After giving it some thought I'm going to go back to square 1 with my tune and start from scratch with the original VE tables. I just looked back at the second log I took before I killed my MAF (and subsequently started tuning SD) and the IAT was over 100F then. In hindsight the knock map wasn't bad at all. I had to remove a lot of VE up to around 3000 rpm, and I'm beginning to think it wouldn't be bad to leave that more or less alone except for 0-1000 rpm where it was so ridiculously rich. It was raining the day I started tuning idle without the MAF and I nearly passed out from the fumes in my garage waiting for it to switch to CL.

[spfautsch]

I think I might have got into a situation where the more timing I removed the worse it got because it would fall on it's face sooner.

A funny thing happened when I tamed the max spark retard table from essentially stock to this:

0.00
0.00
0.00
0.00
0.00
0.00
0.00
1.50
3.00
4.00
4.00
6.00
6.00
9.00
9.00
9.00
12.00

All the banding in the knock plot went away. So apparently the knock sensors were picking up a misfire or who knows what from lugging up a hill, and I'm guessing the resultant KR made it snowball by worsening the cause.

I'm back to closed loop for the moment. Other than testing the lower max retard settings I did some trial and error with integrator delays and found settings that have the worst BLM split over all cells around 2.

[spfautsch]

So I switched back to speed density last night in anticipation of doing some logging today and my idle went back to garbage. It hunts, and falls on it's face when feathering the clutch. I've tried bumping integrator / transport delay to ridiculous numbers and it still wants to die taking off. So it sounds like I'm definitely going to end up with an open loop SD tune, as enabling the MAF takes all the bark away after 4000 rpm when the cam really starts to wake up.

Makes me wonder if a hack to enable MAF at 0 tps would be possible, but doubtful I'll end up caring about closed loop after VE tables are baselined.

Steveo - do you think there would be any value in installing widebands in the narrowband bungs in the collectors? If not I would have to yank the cats.

[steveo]

So I switched back to speed density last night in anticipation of doing some logging today and my idle went back to garbage.

so, your VE table is out to lunch.

as enabling the MAF takes all the bark away after 4000 rpm when the cam really starts to wake up.

at high rpm where airflow is much more linear, maf and speed density should be fairly equal. so your MAF table is out to lunch

Steveo - do you think there would be any value in installing widebands in the narrowband bungs in the collectors? If not I would have to yank the cats.

yeah, that's a great place, go for it

honestly, the more i listen to you the more I think you're tuning by these feedback numbers instead of by feeling what the engine needs. if it's limp add more fuel. if that makes it worse take fuel away instead.

[spfautsch]

so, your VE table is out to lunch.

at high rpm where airflow is much more linear, maf and speed density should be fairly equal. so your MAF table is out to lunch

I guess I missed adding a qualifier to that sentence - the idle goes to $* when it switches to closed loop SD. Before it's up to temp in SD or with the MAF in OL or CL, idle is awesome. You can barely tell it's a 230 degree cam. Not sure if you caught the post where I stated I'd switched CL back on. Whatever the case, yes, VE needs to be addressed.

Drove it yesterday with almost all non-PE KR disabled. Found some interesting stuff out. See below.

honestly, the more i listen to you the more I think you're tuning by these feedback numbers instead of by feeling what the engine needs. if it's limp add more fuel. if that makes it worse take fuel away instead.

I agree, you've converted me. But I think I need to resolve item #1 (VE table out to lunch) first? My first attempt earlier this month at getting VE close wasn't good as I'm still learning, but I think this approach will be better. Here's what I started on yesterday.

ve-tuning.jpg

This should be relatively close and a lot smoother than what I ended up with tuning the table directly (and a little haphazardly) with trimalyzer. I still need to smooth some of the edges manually - this was aiming at -4% (slighly rich). Unfortunately my clutch slave has gotten to leaking worse and I'm afraid that's going to have to get fixed before I can log with this change.

A few things I observed yesterday.

1) When I switched off the MAF the other night I forgot to increase the PE Enable TPS vs RPM table so I get a broader range of feedback for logging. When I did this for the drive home the mid-throttle power was noticeably much better. Much, as in accidentally smoking the tires at 2800 rpm where it's never really displayed that much torque with this cam. I'm wondering if the narrowbands aren't as inaccurate as I began to suspect, and my VE table is just way too rich.

2) Without KR at cruise I started to notice knock counts at the oddest place. I had assumed this was primarily happening while lugging up a hill in 6th @ 75mph, ~1700 rpm. But I noticed none of this yesterday. More often than not the knock counts seem to happen after cresting the hill when TPS starts to decrease. I'm kind of baffled with this - wonder if it could be going a little rich and popping when the unburned fuel hits the cats (it's not plainly audible).

3) Lugging up a hill in 6th in that load range is not generating much along the lines of knock counts, but the engine is definitely not smooth. Almost feels like a cylinder is dead or way out of balance, but when you rap it to 6800 it's as smooth as glass. Now that I'm sure the knock isn't real I'm hoping I can play with timing in this range and see if it can get better.

[spfautsch]

so, your VE table is out to lunch.

You had it pegged. Applying some changes that added fuel in the 400-1200 rpm ranges that were lean by 8% or so has smoothed idle down considerably.

I think I've realized what's been causing my problems - tuning with too little data. After gathering logs for several days and setting a target of -3% in trimalyzer I was just applying all changes. What helped immensely was setting the minimum record count to a fairly high number. For me 750 really helped weed out the cells that haven't gotten enough "law of averages" applied to them.

This has brought me to the realization that I'll be logging data all summer to get enough to correct the areas outside of normal cruising. Calibrating my MAF will have to wait until at least next summer. Will probably need new tires by then as well. :)

[Terminal_Crazy]

Hi
I've just pent the last few weeks using trimalyzer to get the ve tables all smoothed out.
After spending 2 evenings swapping the shifter (springs gone soft) for the hurst the wideband went to shit.
I'd trapped the 02 sensor cable.
In the process the ve tables are now screwed.
Went OL. It was idling at 22:1.(quite happily)

Ve tables were maxed so dropping injector size 2 points (5%) it was idling at about 12:1. Pe is about 9:1

F***me does the car like that. It howls now.

Obviously explains why o2's and wideband didn't quite match but was never that far out when using CL

It definitely does like the fuel.


After The run (a really good one I might add ��) Idle had dropped

[spfautsch]

I'd trapped the 02 sensor cable.

edited for brevity...

Obviously explains why o2's and wideband didn't quite match but was never that far out when using CL

I'm not sure I follow, but I'm intrigued. Care to explain better - I can be a bit slow on the uptake.

Idling at 12:1 must smell pretty raunchy - are you parking in a garage? Woof!

I just spent some time fine-tuning the A/C and did a bit of test driving. When I initially charged the system last sunday (before applying VE corrections at idle) it died twice on me. With the "better" VE corrections it actually idles a little more steadily with A/C on, likely from the additional load causing more IAC opening / airflow. I can't imagine running a cam like this with an aluminum flywheel. The way it's running currently I can back into my driveway without instantly killing it, but backing uphill into the garage is still a little dicey.