SkinnyG's V8 Pontiac Firefly

After the header gasket, I went for a rip. Out of sheer misery, I just went fatter and fatter just to see what it would do. Within a couple blocks I could feel where the surging was, so I'd pull over, fatten each VE bin 5 steps, burn, and try again. We're looking at about 50% fatter now in and around 30kPa. It's running far FAR -FAR- better now!

Here is the resultant VE Table so far, with lean surge almost all gone (this table is by no means final, I just needed to get out of the heat for today):



I'm also noticing not only did the BLMs never go over 128, once I restricted the BLMs to stop going below, today I noticed the INT not going above 128. Interesting. I found a similar experience at https://www.thirdgen.org/forums/diy-prom/751919-integrator-capped-128-a.html, so I looked through my own tune and turned the DFCO limits back to what was stock. I have not tested this, so I don't know if it made a difference.

(I had previously tried to have a bunch of things "off", so I can just tune VE without all the stupid adders.  This ECU doesn't understand "OFF". I tell it to not go into closed loop until 255mph and it still goes closed loop, and I don't even have a VSS. I tell it to not go closed loop until 105kPa, and despite the altitude here being 96kPa, it goes closed loop.  It's drunk.)

Corrected the above post.  Apparently I'm drunk.  I can't shut off closed loop.

Later tuning last night had some issues.  It all went for a crap and I couldn't make things better. I did a ton more research, and slept on it. Made some changes and went driving/datalogging, and well, Can I get a BOOYEAH!?

It's working SO much better now. Even better than the best of yesterday. If this were a carb, I'd be like "dang, that runs good!" Here's what I did:

I changed the O2 Voltage Thresholds, because what GM did made no sense to me:

I then reduced the O2 Proportional Gain more and more until I stopped getting lean surge and O2 voltage got more under control. This is maybe 60% reduction or more at the very low end of things, and 25% reduced at the top.

I tell you, trying to understand how to hack this stuff when you're not an engineer or fluent in Hex is frustrating.  I -think- increasing the O2 Prop Gains makes the computer react MORE with changes in O2 voltage (which, in my case is acting like lean surge, and making it difficult to find a good VE valve). Conversely, reducing the O2 Prop Gains makes the computer react LESS to changes in O2 Voltage.

The VE table looks a lot better, but you need to know that GM only cared about things below 3200 (all tuned 14.7 and closed loop). The VE table stops at 3200, and then to rev higher, there is a VE Adder table.  I think.

I'm a whole lot more pleased, and a WHOLE lot less pissed off today than I was yesterday.

I'm not going to spoil it though; I'm going to wire up a bathroom fan and some inlet vents for my compressor shed. Work on something else before I ruin things again.

Awesome! 

Today I reduced the Injector Bias by 20%, and increased the VE table by 20%, turned off PE, unlocked the BLMs from 128, and went for a drive. 20% brought the highest VE to 90.

Had a slight surge at 2000 and 30kPa, but I got some good datalogging in. The INT was doing its thing, the BLM still went lean, but not so dramatically. Engine still ran pretty good. Corrected the VE table using BLMs, then zeroed everything in Decel Enleanment and drove some more. BLMs stopped working (I have since returned the DE settings to factory).

Nevertheless, I still datalogged, but checked the INT History when I got home, and they were all very close to 126-128 themselves.

This afternoon I've been playing with subtle changes to the Spark Table.

I'm hoping that as the VE gets closer, and the INT and BLM is happier, I'll have less issues with surging. It -does- seem to be improving itself as I've datalogged and tweaked the VE table.

I had an epiphony.

The engine can't hit 14.7 at idle (50kPa), and it isn't fully happy cruising at 2000rpm (30kPa), both of which are coincidentally running the same VE values in their cells.  PERHAPS, at 18psi, the injector cannot run a small enough Pulse Width to reduce the fuel enough, to run consistently enough, with such high fuel pressures.

Quick Googlefu seems to show discussion of idle quality issues creeping up above 18psi fuel pressure.

Since I just swapped to an external fuel pressure regulator, which can be vacuum-referenced (I just haven't used that), perhaps it would be wise to hook up the vacuum, so I can run lower pressure at high vacuum, and get full pressure at full throttle?

Sounds like a plan, Stan.

Results to follow.

(edit: music free zone)

I think what you had is an epiphany. 

I have an Epiphone, but there is another thread for that.

Edit* sorry, couldn't help myself.

Hmmmmm...... it's ringing a bell.......

With the vacuum-reference hooked up to the external fuel pressure regulator, I now have 12psi at idle, which is right where stock wants to be on a TBI system.  Except now I still get 18psi at full throttle!  Nice!

Did a few datalogs and tunes this HOT evening (40°C/104°F, my igloo has finally melted), and the BLMs are staying really close to 128, and it's driving really really well.

The pleased is deep with this one.

Lol.. It's a DRY heat...

Yup.  Feels like 32° where you are, with humidity that sucks the life out of you.  I left my umbrella down there when I moved away. I'd rather slit both my wrists with running, flaming, chainsaws than move back there.

I ordered an oil cooler from Jegs, which has landed in Richmond right now, so it will likely be here by Wednesday or so.  Hopefully this can drop some engine temps down significantly.  I need some heat shielding, too, so my shoes don't keep melting from the header.

It looks like we're really sorted now.  Enough that I'm putting the laptop away and calling it good.

I did do some minor tweaking this morning before it got too hot.

Fattened the idle a bit, O2 numbers be danged, I want a stable idle. Good solid and reasonably low MAP signal here.

Dropped a bit of Spark Advance where there appeared to be some vibration. Weird that it's a narrow rpm/map range, could be driveline issues? Dropping the timing a few degrees seemed to make a noticeable difference. I'm still running a LOT of timing at light throttle, and idling at 28° advance. It works, trust me.

Nutshell:

I -think- dropping the O2 Proportional Gains made a difference.

I -know- running an external and vacuum-reference-fuel-pressure-gauge made a significant difference, and really was no added challenge to tune.

It's pretty darn reasonable to drive despite no VSS - all emissions are deleted, no spark adders, lots of tweaking to IAC, throttle-follower, stall saver, and decel-enleanment. It's pretty decent. At this point DFCO is still disabled.

My mad tight skills in ECU tuning have now hit the 1990's, man! Word!

Oil cooler arrived.

It's all installed, except I need to get a PH8 or FL1 or equivalent filter.

Glad to hear you're getting it sorted out!

Picked up an oil filter today.  Leaks at the barbs into the block adapter (now fixed), and relatively loose fitting hose to barb (now really freaking tight).

Haven't driven it yet, but at least it doesn't leak.

I yoinked the simple hose clamps on the block adapter for the oil cooler, and used narrower hose clamps doubled up (screws offset from each other) to improve clamping and sealing. If you're going to buy the kit, maybe get different hose.  I didn't measure the barbs to see if they are truly 1/2" or not.  The hose is a loose fit.

Finished building the battery-disconnect knob, as per drag rules. Still need to label "OFF" once the paint has cured a bit more (Tremclad "Hammered" finish, one of my favourites, right up there with "Bed Liner").

And started replacing the interior paneling for a more finished look. The rear plastics are almost impossible to find, so I took my time trimming them. The full side panels will be one-piece gray-vinyl-covered hardboard for simplicity.

Correct me if I'm wrong, but is your electrical cutout handle mounted incorrectly? I feel like it should be pull = Off, not push.

I do like the routing through the taillight. Clever.

Hmmm.  I don't know.  PUSH made sense to me...

Push is correct.

Quick Giggitygoogle says PUSH is the expected way to turn off.

A label saying push off would make it so there is no confusion too.

I was so excited to show y'all, the hammered paint wasn't cured enough to letter it yet.  That's one of today's jobs :) .

"My mad tight skills in ECU tuning have now hit the 1990's, man! Word!"

And I still haven't the slightest clue as to what you've addressed and rectified......

Would a PM be a more appropriate avenue to query your diagnostic journey  so far .....and are you going to have to charge me admission for night classes??  

I don't know if I could easily explain what I did.

I had to make the computer understand and properly run the 350.

The ECU appeared to be over-correcting to the O2 sensor (it may not have been).

The stock 350 injectors don't flow enough fuel for what the 350 needs, so I had to raise fuel pressure.

Raised fuel pressure made idle and cruise difficult because the ECU cannot control the injectors slow enough.

Modifying the factory fuel pressure regulator for more pressure was fail - it couldn't work consistently for me.

Making fuel pressure vary based on engine vacuum was a win (it isn't vacuum-referenced, by the factory).

LOTS of tuning in the ECU relies on a vehicle speed sensor, which I don't have, so I tried a variety of work-arounds to make it happy enough to run well enough without it. I have mostly win.

All this along the way to resolve "why does the ECU keep pulling fuel when the engine is clearly running lean?" to which I'm not really sure I nailed the answer, but the car appears to work fine now.

Does that help?

Ask any question - others here might have the same question. I don't even have answers.....

Took it out for a drive (it has probably sat a week??) the other day, 100°F weather outside.

Oil cooler not really helping significantly.  I sort of expected that. Probably be happier if I actually wired in a proper cooling fan switch, so I don't have to keep the eagle eye on it.

Still had some surging at low kPa.  I did a bit more research, and i'm going to turn down the INT Multiplier and see if that helps.

SkinnyKids 1 & 2 are away at camp, so I should get some good stuff done. Namely, I want to finish the interior panels.

.... except I'm fixing the seat bottom on Mrs. Skinny's Infiniti.

.... and paving the driveway a bit wider.

.... and painting the upstairs doors.

.... and building a battery box for the Firefly.

.... and and and