SkinnyG's V8 Pontiac Firefly

Interested in what the issue is.

The engine is definitely running lean based on what you can see when driving, but the O2 thinks it's still too rich. The O2 sensor isn't the issue since you've replaced it. So either it's mechanical and that one cylinder it's mounted in really is running rich (intake manifold distribution? I know very little about small blocks), the wiring between sensor and ecu has an issue that feeds a >0.5v signal constantly or the ecu itself isn't using the O2 data correctly.

Can you watch ecu data with the moates stuff you've got? I've got their demon module in my obd1 Honda that does that. If not, maybe just backprobe at the ecm what the O2 is reading while running. See if it's switching at all? Not sure how to limit fuel to the one cylinder on a tbi setup. If it was reading lean you could have added propane to a vacuum line while running to force it rich. Might be able to see it go lean on fuel cut off after you snap the throttle shut?

I -could- run a Rochester.

Or, I could just mute the O2, and tune the TBI like a Carb. I won't have to pull the carb any time I need to do something, and I won't even have to smell like gas. I mean, everything is -there-.  Plus: The 1970s are over, man (says I, to you, oh classic car restorer...).

I can watch the ECU data, yes, using TunerPro RT. I can see the O2 slowly increase in voltage as it warms up, and then it begins switching (about 1 minute mark, last datalog).

MAP signal is what is expected. ECT and IAT temps are expected. All the signals -appear- clean.  Honestly, everything was unplugged from the 305, and then re-attched to the 350.  While the TBI and injectors are different, the TPS and IAC and Injectors are a known, running entity, and they test alright.  Odd.

I'm currently going through the Factory chip from the 305, and making sure I didn't screw something up with the burnable chip.  I've found a few wee discrepancies (I used a "factory" bin off the 'net.  It looked pretty much the same as what I had.  Now I'm -making- sure).

I just look at the fight some people have and ask myself why.

Carbs are 99% as good as fuel injection on an engine with a relatively sane camshaft.

Carburetors have been working perfectly longer than EFI has been working perfectly.

I'm not saying they're better than EFI, I'm not even saying they're as good.

I'm saying that for a stock 305 or 350, they're more than good enough.

You know as well as I do that if you bolt a stock Q-jet off of any similar sized engine onto that thing it will be set up nearly perfect right out of the box. It's not a Holley after all.

Now that I've said my piece I really do love your pants-on-the-head crazy projects. This one has got to be my favourite so far.

If I finally snap, I have a Rochester and HEI to put in.  But it just might be "the thrill of the chase" and perhaps "skill mastery" for me.  I usually bookend my projects with "...because I'm stupid..."

There were a lot of subtle changes between the chip I pulled out of the Firefly, and the bin I scooped off the net.  The one off the 'net is the right bin for my ECU, except it was a manual trans with 3.08 gears, vs. my 700R4/2.73 Firebird. I made them all the same.

One area where there were some significant differences is in the "Throttle Follower" section, where the IAC control keeps up with what your throttle is doing to make things smoother/whatever.

I also changed when open loop can look at the engine, namely setting the minimum MAP higher, and raising the minimum rpm to higher than idle.

All that really doesn't fix the fact that it was sending me further and further into lean-surge cruising around the neighbourhood.

Some research suggests that EGR coming out the exhaust will make the O2 see "rich." Except I have no EGR at all, just a block-off plate.

Pics.

Sooty O2 sensor.  Probably original.  I bought a new one just to rule it out.

Evidence of my WD40 hosing to find a leak. New gasket fixed that.

Small block TBI gasket doesn't fit the Holley big-bore base well. I bought a 454 gasket, which is larger where it needs to be.

Not sure if it helps but last year I swapped a Holley HP-EFI system onto a RamJet350 crate engine which was running like garbage on the stock Mercruiser fuel injection system.

The only reason we swapped computers is because you can't tune a RamJet ECU with a laptop unless you spend more than the Holley system is worth on software and then it only works on that ECU serial number.

The RamJet350 is pretty much an L98 Tuned Port system so a little different than yours.

I ran into a lean surge like what you're describing and the problem I had was the HP-EFI was responding too quickly to changes and making the surge worse.

There was a box somewhere in the software that I altered to slow down how quickly the thing reacts and it smoothed everything out and it purrs like a kitten now.

If I remember, it was something to do with the IAC motor

Not sure if it applies to your situation or not.

Sounds similar; I'm thinking the same.

I'm looking to see how I can slow the reactions down.

There was a difference between the 'net bin and my original in the "INT Delay Base" which is supposed to help "time" the readings to the occurrence. Since all this worked fine with the old motor, I'll try out all my "get-them-the-same-as-before" tweaks this evening first. I'll likely move the O2 down to the collector anyway, but later.

-I- don't think this should be so vastly different. I mean, it's only a bigger motor, with bigger heads, with a bigger cam, with a bigger TBI unit, with higher fuel pressure.  I mean, what gives? Sheesh.

"Throttle Follower" on the manual transmission tune was 75% - whatever that means.  In my datalogs, the IAC was moving a LOT.

"Throttle Follower" on the automatic transmission tune was 5.9% - still don't know what that means.  That sounds like a significant difference.

If the ecu is set up for AIR the ecu will look for a leaner condition when it activates the valve for the AIR it sounds like when it goes to close loop it sees a false rich and leans it out because it turned on the AIR. The solution is to raise the AIR turn on temp to the max the ECU will allow.

Last night I went through the 1988 5.0L TBI tune I got off the net, went through every scalar and every table, and compared them to the original factory tune pulled off the original chip from the running 5.0L.  There were some significant differences, especially in IAC (Idle Air Control). There were a lot of subtle other differences, but I matched everything from the factory tune, with the exception of -my- Spark Table, a different Injector Constant, disabled EGR, and removed potential trouble codes.

Also, I machined an O2 bung and welded it into a header collector, just removing the possibility that the O2 I was using was too close, or getting a poor signal. I ran a long wire up to where the original (but now new) O2 sensor is, so I can change back and forth if things went south.

Woah! OMG LOL WTF TGIF CIBC TTFN ESPN TSN TMO! This beast is WAY better!!!

O2 sits at a pretty decent 0.447 until it's active, and it actually responds! Mind you, it's not heated and it took a while until it was warm, but wow it is so much better.

Clearly, the next step is to hook up the Wideband and do some WOT testing. Clearly. For Science.

Good call, Zordak, on the AIR. I went back and check the very first tune I had started with - it had the AIR minimum temperature at -18.3°C.  I doubt I ever ran that tune, because the next saved tune was 45 minutes later. Not really sure -where that number came from. Yesterday's tune had the AIR programmed to turn on at 109°C (228°F, as per OEM), but I had issues below that temperature. Nevertheless, for today's tune I set it to maximum.

Since I'm not using a VSS, I'm hoping I can re-program the VSS input into a 0-5 Analog input so I can read the WBO2.....

Home-made "WinALDL cable", plugged into the USB-Serial converter I got from  EFI Analytics back when I TunerStudio'd Megasquirt on the Super 7

Easy-access ECU. home-made chip-puller-out-inator and Burn2 on the glovebox door. Useless VSS Buffer (yellow) since the car isn't speed sensoring. Useless PCMCIA-Serial adapter (never did get it to work consistently).

Went for a drive some more today.  O2 still reads slightly rich, but the engine is "feeling" lean. I'm learning how to much with thresholds and corrections. Shame I'm using such a simplistic ECU.  It's a pretty decent runner so far. I think I figured out how I can datalog the wideband, so that might be tomorrow.

Comfort-wise, how is it driving with so little space for the feet? 

It takes a bit of getting used to - your feet are shoved way over to the left.

I cannot integrate my WBO2 sensor into the factory ECU.  I was hoping to just feed 0-5V in, tell the computer to stay on open loop, and set the Definition file to recognise the 0-5V. Problem is the ECU is not happy seeing more than 1V on that input, so it isn't working.

The fellow who created the mask for this ECU didn't make an alternate input available so I could feed in a WB, so I cannot datalog with it.

So....

I then failed at making a 20-LED bar display using two LM3914s.  Something is wrong, and my eyesight ain't what it used to be.  And I think I fried one of the chips, and I'm just getting pissed off. I think I might just shove a Voltmeter on the dash and keep an eye on 2.125V (I think.....).

Spent ALL day mucking about going nowhere.  I could have just played video games and gotten just as far with it. Not a happy camper.

You could have driven it by now. 

I will not be dominated by this inanimate object.

I've been driving it a lot, thank you very much.

It has a slightly raspier exhaust note. It doesn't -feel- all that much more powerful.

I gave up on trying to have something cool and magical to read the WBO2 - I just connected it to my DVOM and held it in my hand at full throttle runs.

While TunerPro can datalog the BLM's, and a simple spreadsheet can run calculations and give you new VE's, but I ended up narrowing the table down much faster by looking at the average O2 voltage in each cell and tweaking the VE directly. Weird.

Except now my DIY adjustable fuel pressure regulator is just not maintaining its pressure.  I'll shim the piss out of it tomorrow, and remove the "misadjustability" of it.

Skill mastery, dang it.

I machined a 0.410" chunk of aluminum to shim under the Fuel Pressure Regulator spring bucket, which gave me 20psi fuel pressure.  Feeding 61lb injectors that were supposed to run on 13psi, should be able to feed about 350hp. That should be ample.

Now to go test and tune....

I recorded the entire ordeal to do a video, only I apparently did not press record..... Grrr.

No.  Wait.... New pump for the dishwasher arrived just now....

Nope.  New pump arrived damaged.  Off to test and tune.

I -had- been using a spreadsheet I found at gearhead-efi.com that takes your VE table and datalogged BLMs and gives you a new table, but I found it kept getting leaner and leaner and leaner.

More and more I began tweaking the VE table based on what I saw as an average datalogged value of the O2 sensor.  To rich? knock it down one or two points.  Two lean? Fatten it up one or two points. But I still wasn't totally happy with the operation.

This evening I went a bit old-school, and set what would be manifold vacuum. That is, I set the lower MAP spark settings (30, 35, 40kPa) base 16° timing plus full 12° vacuum advance, then added mechanical advance.  So it idles at 28°, and if you were cruising at 3200rpm you get 48° full advance.  This drops right quick from 45kPa to 50kPa, but leaving some decent advance around my 50kPa idle (cruise is 35 - 45kPa).

This felt way, way, way better. Drove better, ran better, idled better.  Nice.

There is still a bit of a stumble as I come off throttle, but that might be something to do with the throttle follower.

It has not yet, at any time, fallen on its face in acceleration like the stock 305 did. That's gotta be a plus.

I've learned some new stuff.

The TBI comes with two 61lb/min injectors at 13psi.  This is enough fuel for about 225hp.

This engine should theoretically be capable of 325hp.  That needs 85lb/min injectors.

85/61 = 1.4, and 1.4x13 = 18psi that I need to run my injectors at.

But, the higher pressure you need to run, the longer it's going to take to OPEN the injectors (ah! The thought plickens).

In the GM TBI ECU, you need to change the "Injector Bias" if you are changing fuel pressure.  If I changed pressure 1.4x, then I need to change the Inj. Bias 1.4x.

I didn't do that.

But I will tomorrow!

That worked wonderful.  I'm very pleased!

Paneled off the openings around the rad with ABS plastic in hopes to improve cooling.  We've been pushing 98°F for a couple weeks now, and while the car is fine in traffic with the fan running, it gets warm on the highway.

I also put some plastic down below the bumper in front of the rad like GM did to try and scoop that air up into the rad. I may also panel over the cowl vents, just in case air coming in through there is negating flow through the rad.

Another option is to slow the water pump down (I have an 8" crank pulley instead of a 7" pulley), but I'm not convinced that's the problem.

Other than that, still mucking with tuning when I can.