Well, I've been rolling into the throttle a lot more lately, as I work on the tune, but have come across a small problem, on the launch....

I don't really spool up until 2nd gear (.84 A/R T3 hot side) and it pulls REALLY DAMN HARD for only 7psi once it's moving... but 1st gear is simply flooding out. I'm using PE mode to bring more fuel in, as the boost comes on (and it works great, in 2nd, 3rd, 4th, 5th) but in 1st gear, before the turbo has a chance to spool up, I'm flooding up if I get onto it too quickly.

I'm at a total loss as to what I can work with here, to prevent that from happening, short of a FMU, or do this '730 swap I've been threatening to do...

I just want to see what I can do with the MAF, first, though. Anyone out there running a large turbo on a MAF setup might could point me in the right direction?

 

I take it the MAF really wont read flows high enough for the tubo'd 6? Sounds like theres not much that can be done if your using PE to bring in the correct ammount of fuel rather then using the actual airflow to control the fueling. Best thing would be to switch over to a SD cal that can see boost. $58 is the most logical choice.

 

Well, my second choice is this -

I can rescale my LV8 scalar down, as my fueling is based on LV8, not actual MAF readings. This will reduce my resolution, yes, but I will then be able to control the fueling for the turbo more from the LV8 vs PW table, and less from PE.

I have a copy of a bin where I had done just that, but since I have no datalogging capabilities (software wise, even TP can't log for me ) I hadn't gotten very far with it.

I suppose I can use the raw output from WinALDL, though, to check it...

Basically, on my LV8 scalar-changed bin, instead of idling with an LV8 of 67-70, I was idling with an LV8 of 40-42. I had to rescale EVERYTHING, though, in response - Timing, fuel, AE, etc.

That may be the best way for me to go. I'll work on that today.

I'm really interested in yours, and Grumpy's thoughts on this - as I have yet to see any posts with anyone running MAF, adjusting the LV8 scalar...

 

well ive done it with the box you have now. and as ive told you in the past the best fix right now is to use a GN maf.youll need the GN maf tables and scalars and youll have to rescale alot of stuff but its dfinately better then what you have right now. its also a direct plug in. it should also have enough flow overhead to cover the amount of flow your little 2.8 3.1 has at the boost levels your at right now . if you run into limitations there, then your next course of action aside from a ecm swap is to get a maf translator and use an lt1 or ls1 maf.

 

If you look at the GN calibration, they use the PE TPS enable, and RPM/TPS PE corrections to get the car up and running.

The quicker you ramp up the LV8, the sooner you max out the fueling. So you wind up too rich, and the fade to about correct as your engine gets to full load.

What you need is another correction for the LV8 based on MAP, if you want to stick with MAF based code. Or dump the MAF, and work on developing a true 3 bar calibration.

While 7 PSI is 7PSI, that only where the fun starts...

There are 9 sec GN MAF cars, but they all are using the ME series of chips, which have a serious amount of code rewritting. Primarily to get them to launch.

 

I started that route, and decided it wasn't worth it. The 3" MAF is going to be a restriction with a 4" turbo inlet, no matter how I cut it - I will end up going MAP based, probably with the $58 code on the '730. I've got the pigtail that i need, and the stock prom, I'm just waiting to get the hardware req'd from Moates.net.

As far as the chip you burned me, I do appreciate it, but all you did was rescale the PW vs LV8 table, and Table 6 of the MAF. Considering the MAF was never changed, I saw no reason to adjust the reported values to the ECM. It just seems.... bizarre, to me.

Anyone feel free to correct me, but the MAF tables are used by the ECM to determine how much air is flowing (this is for the fq film V6 MAFs, NOT the hot wire V8s, guys!!) vs fq. The MAF itself is calibrated a certain way, and the MAF tables are calibrated TO THE MAF. Sure, you can fudge the fueling by altering the amount of air flow reported, but the fact is, if the MAF is calibrated so that X amount of air = Y frequency, then the ECM uses the table to read that back as Y frequency = X amount of air. I would rather the ECM is reported the ACTUAL air flow, than a 'fudged' (higher or lower than it REALLY is) number.

You never adjusted the LV8 scale factor, as in your bin, it is still set to 1.81. Considering that my fueling and spark are based off of LV8, NOT MAF readings, I'm very much wondering exactly how much overhead there is to be found, via the stock MAF. Obviously, LV8 readings hit a wall, once the MAF is truly maxed out, and can report no higher frequencies.

Right now, I'm working what I can, with what I've got. The GN MAF is no bigger than my stock 2.8 Delco MAF, so I'm not going ot gain anything other than more flow overhead... I already have a bin set aside, exactly as I have it now, with the GN MAF tables in. I will be changing to a GN MAF later, when funds permit it.

Grumpy, I appreciate the info on the GNs. That was EXACTLY what I was wondering - how they differentiated rpm based fueling, without knowing if they were under boost or not. I can not help but wonder, if I were to scale my LV8 down, if I could obtain enough room to determine if I were under boost or not. I'll be working with it more, and reporting back (not that anyone has any care how a '302 ecu in a '86-89 MAF 2.8 does things )

Looks like I'll be moving to the '730 quicker than I thought. I'll place my order to Moates tomorrow evening, and work on it more next week. In the meantime, I've got an SU129, the '730 ecu, '92 Memcal from a 3.1, and the wiring from it. I just need to build an adapter harness, while I wait on the new parts to come in.

I will continue to work with the '302 ecu, in the meantime - I'm simply learning everything I can on this.

My current plan, is to go run a couple datalogs and see how high the MAF reports. I seem to recall that LV8 of 255 is hit around the time I get to 110g/s, WOT. If that is the case, I should have enough room to get to the MAF's max of 150g/s, before I hit LV8 255. What I wouldn't pay to have TunerPro's 160 baud datalogging working

And if I can get that, then I can do more fueling based off the LV8 vs PW, and less off the %Change Fuel/Air @ WOT vs RPM table.

Thoughts? I'm trying to instigate discussion here.

 

The faster 8192 baud aldl is reason enough to upgrade to the 730... (not to mention all the other cool stuff you can do with it)

 

That LV8 vs. PW would be enough to get me to switch over to the 58. Thats basically using the actual airflow to simulate the engine load to approximate the PW. Might as well use a map to measure the actual engine load. The V8 mafs use teh actual airflow to calculate the needed PW. Much better IMO. With some minor code changes you could probably change the V8 MAF calc to match a V6. With those there is a divide by 8 built into the injector constant to account in part for the #DRPs per rev in order to make the needed inj. DC a time based PW.

 

Are you sure you're flooding out? I thought I was early on, but it turned out that the stock NA spark table had too little timing at lower RPM / higher MAP cells. When launching in first gear, by 1400rpm, MAP was at 100kPa and the SA for this cell was 20 degrees. So I'd go from idle SA of 26d and drop to 20....it felt just like a rich bog and of course, the WB readings helped convince me of that.

Now that I've redone my spark advance table, no more bog, just tire spin! As a comparison, my current SA table now runs 29d of advance at 1400rpm/100kPa. The main fix for me was not pulling timing during a hard 1st gear launch.

 

ZT-2 is showing an AFR of 9.9, flatlined.. yeah, it's rich

 

Are you limiting yourself to just thinking about a draw thru MAF?.

Having two tapered hoses on the discharge piping isn't a problem, ie putting a 3" MAF in 2.25/2.5 piping.

Since the death of the $60 code, the ills of the 58 haven't all been cured. The 58 is about the best easy to use boosted code out there, but it still has issues.

For a boosted engine to be as happy as possible reguires alot of resolution in the various tables. There's alot of lost HP in boosted applications, due to poor resolution, from what I've found. The boost multiplier table is alot better then nothing but it needs to be a 3d table. The one thing, real good thing about the 58 apart is that it is designed to actually use a TRUE MAT. That's a critical issue, IMO.

Initial boost varies an incredible amount on some applications. The best MAF setup (after alot of experimenting), that I was able to come up with used a MAP sensor, and voltage divider to input the MAP into what was the IAT/MAT. The 31T (GN code) had an unused IAT timing table, and then the normal IAT MAF correction. So I was able to feed a boost refenced correction into the ecm. It worked alot better then anything else I tried. In the end I went to a pure MAP system. If you get into working on the 5B series of codes, in the 94MY version there's a ton of code for MAF corrections. At least more then I was expecting, and the one application is for the S/C version. You almost have to have an ecm bench for getting doing something like this....

 

Yep, that's what I was experiencing....it didn't need as much fuel because of the retarded timing. I pulled fuel, changed plugs, wires, etc. Adding timing is what the engine wanted. I was even starting out with a SA table meant for boost, BBZB $58.

Look at your ALDL logs to see what's happening with SA. Might be worth a try....

 

*sighs* As much as I would like an ECM bench, I feel that particular endeavour is still far over my head.

I haven't seen much work on the $8F code (89-90 TGP), and I can't help but wonder why this is. Perhaps that they, being rarer cars, don't see as much light shed on them, as the Sy/Ty?

I'm giving a lot of consideration to running the $8F code, since the '727 is simply an underhood '730, correct? Between Lean Cruise, and Launch Mode, that I see TC supports on the $8F, but I do not see on the $58, I think that's the way I'll be moving.

Besides, 3.1L + 22pph injectors in the TGP, stock - so I think I'll have a VERY good starting point... just have to get around that whole DIS system (I believe that is done on the Ref Angle)


Grumpy, you're right - upstream would be much less of a problem. But for the price of the MAFT (I already have the LT1 MAF) I can't justify going that road, vs the '730/$8F

 

well as i told you originally i lied to the MAf tables to help cover the fueling.from experience i new that there was a tiny bit of range left in the sensor. maf translators are not that exspensive about $150. the GN maf has more flow per division of FQ which makes its resolution much coarser then what you have now but it also will read more total airflow. i dont see you maxing out that maf at your current boost level.

you could in fact modify the lv8 scalar and get aditional timing control. this is of course the only reason to do so. also it would give you more dynamic fueling. i always found the 302 ecm to be very very easy to work with. just a bit dumber then the newer models.

id agree that MAP $58 in this particular situation is a vast improvement over the system in your vehicle now. but $8f is a buggy peice of code that doesnt ever seem to work correctly. if i were you id go $58.

as for resolution yeah its important but if your just trying to get the thing to work well enough to make good power a GN maf should get you covered.

hit me up via email if you want to talk at length. ive worked with all these systems.

 

You have your choice, experiment by guessing, or try to be somewhat scientific. Experimenting by guessing, while in the short term might seem cheaper, by the time you figure in gas, and an ocassional engine, long term, you can't afford not to build a bench.

The 8F code is way over the top, in complexity for what a hotrodder actually *needs*. If you want to do some good, take a simple code, and optimise it (ie the 58).

When anyone says they can't afford something that should at least to me, signify the need to do some learning, and be more resourceful.

 

Another option is to ditch the LV8 based fueling as I mentioned above. I year or so ago I posted the core equation that is the basis of the MAF based fueling for the V8 cars. https://www.thirdgen.org/techbb2/sho...hreadid=261961 Taking a quick look at it, scaling the inverse injector flowrate by .75 should provide the correct multiplier for the dist. reference period so the actual PW will be coordinated with the duty cycle.

Might be worth a shot to try another MAF ecm/mask. I dont know how well theyd ultimatly lend themselves to running a V6 but they at least have the cylinder select. In the end this might yield a somewhat drivable car rather then something that only runs good under full boost but is a turd everywhere else. If nothing less, at least it could alieviate some of the LV8 woes.

 

Well, was GOING to hit the track tonight, but it got rained out... so instead, I spent the last like... 6 hours straight just tuning. It's been very fun, and EXTREMELY enlightening!

I've got great part throttle response (as good as stock, anyway) and awesome response under boost. The switch from no boost, to boost, is not super smooth, but it makes it feel like a swift kick, anyway

And here's what I got in return -



I'm going to try adding some more spark... but I'm not hopeful. I added 2º at the lower ranges, where I cruise, and instead of cruising steady at around 15" of vacuum, I don't seem to have the power I did before, and cruise more like 11" of vacuum.... so timing... I'm still working on