91RockS

I'm just getting started doing my own prom tuning on a L03 TBI and have several questions on the fuel and spark tables. I'd rather ask the guys on this board since the really experienced TBI tuners seem to hang out here and are very helpful to the new guys. Moderators, is this o.k. or will you shut the thread down?

ShiftyCapone

iTrader: (7)

This is 100% fine. These are the exact type of discussions we want to see

You have come to the right place. There are some amazing TBI tuners on here. Pay special attention to Fast, Dewey, Bron, Dimented, Bmonte, JP and a few more that escape my brain right now.

Fast355

iTrader: (2)

RBOB!, VA454SS+some more

What do you need to know on the fuel/spark tables?

If you have the stock swirl port heads still on your car you want NO MORE than 32* total advance all in by 2,800 rpm. 44* is acceptable under light throttle low load cruise though.

VE1+VE2=VE total

ShiftyCapone

iTrader: (7)

Yes indeed! Yikes, I left out the most important guys. It has been a long day. Hence the disclaimer

BronYrAur

iTrader: (1)

Yeah I run about 41* or so of timing in cruise, and 30* total advance in at 2800. I think about 23* or so around idle.

I think the best way to go is to rough in a basic spark map, I don't like the stock tables so I start a completely new one rather than try to modify and smooth the stock one. Then tune your VE then make spark adjustments and tune VE again, its all a cycle.

Fast355

iTrader: (2)

I typically start with the old L82 curve from GM. It gives around 28* total advance at 2,800. GM ramped in alot of timing real fast off-idle then kinda tappered it off towards 2,800. 10 @ 10 vacuum advance connected to the manifold. I zero out the PE spark as I feel that it is not needed.

BronYrAur

iTrader: (1)

I agree, I also take out the PE spark, I don't like any spark being added at open throttle besides my table. Do you by chance have a copy of this L82 .bin? I'm curious to see what it looks like

edit: I just did a google search for "GM L82" to see what all it came in, and your sounddomain site was the top search result haha

Fast355

iTrader: (2)

My bad Goggle L-82, they used to have hyphens in them. I'll see if I can dig up a .bin with the L-82 spark table in "Adapted" form. The rpms don't exactly match up.

Initial
8*
Centrifical
0* @ 1200
2* @ 1460
12* @ 2200
20* @ 5000
Vacuum
0* @ 6 in/hg
16* @ 12 in/hg

http://www.nastyz28.com/camaro/tuneup.html

http://www.nastyz28.com/camaro/z28l82.html

Dewey316

When I had the swirl ports, I brought the timing up to 29* at about 3K. Max timing in hi-way mode, was set at 40*.
There really wasn't much of a timing curve at all, I actualy had 24* at idle, but the motor seemed to like it, with the cam I have.

BronYrAur

iTrader: (1)

Oh sorry i didn't realize that was a vac advance distrib curve you were talking about, thanks though, looks like a good place to start. Sometimes i like to try out entirely new spark curves and see what I like best.

va454ss

iTrader: (1)

RBob da Man.

I'm a wannabe

91RockS

Great. Hopefully other guys starting out with DIY tuning on TBI's will benefit too.

I haven't gotten into really serious mods yet (see sig), but as suggested by many others, I'm trying to optimize what I have now as a learning experience and get a handle on tuning before I tackle the head and cam swap planned for this summer. I'm running a 1228746 ecm using $61 mask and AXKW bin on a L03 with T5 tranny. I'm using TunerProRT with JP's "61 for 8746_TBI.xdf" definition file. Flash ROM courtesy of Prominator.

My initial questions are around fueling (I'll get to spark later). I installed a WBO2 right away. I can't imagine how fogged I'd be without the wideband data, worth every penny spent. I started tuning with part throttle and cruise to get BLM's at 128 +/- a few. So far so good. Then I started looking at WOT air/fuel by doing some WOT runs by lugging the motor starting at ~1500 rpm in 4th gear all the way to redline. I noticed the AFR was rich (from 9.5:1 to 11.5:1) all the way, plus there were some very noticeable shifts in the measured AFR that obviously were a result of changes in the commanded AFR. I imported the fuel tables into excel to graph VE1, VE2 and total VE. I noticed several things:

- The stock VE2 table had a non-uniform shape, with a really nasty dip around 4000 rpm. This explained some of the weird AFR's I was getting. I'm not sure why GM did this other than to tune around some unique drive condition or emissions requirement. I've reshaped the VE2 curve to smooth it out and retuned VE's to hopefully get ~12.5:1 AFR at WOT through the entire rpm range. Need more datalogging to find out if I got it right!

- Total VE with the stock cal is in the mid 90%'s and after tweaking the VE's it's only a few % away from 100% at midrange. I'm pretty sure my motor truely is not this efficient and I can see that I will hit the 100% VE ceiling very quickly unless I change the BPW. My question is why doesn't total VE really reflect the true VE of my motor. I'm guessing my motor is really at about 85% efficient at it's peak. In the end, I guess it reallly doesn't matter as long as total VE stays below 100%

- Correct me if I'm wrong, but at WOT, the ecm jumps out of closed loop and goes to the "PE - WOT AFR vs RPM" lookup table to determine commanded AFR. The stock table is really wacky:

4000 rpm 13.10 AFR
3200 rpm 10.50 AFR
2400 rpm 11.60 AFR
1600 rpm 12.00 AFR
800 rpm 10.00 ARF

Can someone confirm for me that for all speeds above 4000 rpm it uses the last cell (the 4000 rpm cell) in the table for commanded AFR??

This table combined with the original dip in the VE2 table I believe explains why my AFR's were all screwed up at WOT. I changed all values in this table to 12.5 but have not had a chance to get back out and log more data as the weather got crappy again and the roads got salted.

I have additional questions on PE and spark, but I'll stop here and wait for some feedback on what I've done so far. Hopefully I'm not too far off base.

Thanks

Dewey316

WOT fueling is a little wacky.

Others probably do it diffrently, here is how I do it.

I set the commanded WOT AFR to what I am shooting for, say 12.8. Then I do a wideband run. I then modify the 100kpa columb in VE1 and the appropriate entry in VE2, until I get that 12.8 AFR on the wideband.

(Note: When you modify the VE2 table, it will affect all Kpa Values, at the RPM.)

Once i get the WB values where I want them, I end up back tuning the part throttle fuel, as I have modified VE2, this throws off things like the 90kpa columb in the VE1 table. Since getting good values in that cell is fairly hard, I tend to just interpolate some of the high KPA, high RPM cells.

BronYrAur

iTrader: (1)

Your PE AFR table looks odd, I'm running the same setup as you, AXKW as well. the PE AFR Table in mine is

RPM
4800
3200
2000
1200
400

Is that not what yours looks like? You did well I think by setting it all to 12.5, that's what I do, do that and then tune from the VE table. Now let's see. The VE2 is an adder table, so at any given RPM you are in a given cell within the VE1 table and you're fueling is that value plus the adder value in the VE2 table. Anything above the 3200RPM limit of the VE1 table is the last entry AT 3200 RPM plus whatever value is in VE2 at the true RPM you are at. Sorry if that comes out confusing.

As far as your question, that is a good one, I am pretty sure, it uses the commanded value in the top RPM cell in the PE table. Also, something that's good to know and why you want a smooth VE table, is that in transitions between cells in VE1, it takes the average of the two cells above and below where you are currently at.

But 12.5 is a good AFR to shoot for before you can go to a track and do some real testing to see what works best. You're at a good place with your setup and having a WBO2, that will help you immensely. Wish I had one haha. I'll be back with more that i think of...

BronYrAur

iTrader: (1)

Oh, yeah, I'd say a good suggestion to you would be to read through this thread: Great Fueling Thread

I always link people to this thread because it really opened my eyes at the time. I would recommend outputting your PW to your aldl stream like RBob explains in that thread, it will help you get your WOT dialed in well.

DM91RS

[91 RockS
14x3 Open element, Accel Wires, Hooker 2055 headers, Hooker Aerochamber Cat Back, Cat delete with Y-pipe dump, Motive 3.73 gears, Detroit Truetrac posi, March underdrive pulleys (power and amp series), ZT-2 WBO2, Prominator]


This looks to me to be a true test of what one can do to maximize bolt-ons on the LO3. I'm glad to see more of the TBI tuning posted here as stated above. You are doing well to also start with a WB.

How do you like the ZT-2?

I can't put off buying one much longer.....(or installing my 3:73/Torsen rear)

DM

BMmonteSS

I see my famous thread has come back once again, , if only I had a WB.

91rocks, you asking all the right questions, and it's very obvious you've done your research before asking. My hat is off to you sir, it's not very often that we get some one new who is willing to do the necessary work in order to learn the ropes of tuning. You should be an example of how to do it.

I also tune my WOT just like these guys suggested, and dont worry about your VE tables not matching up with your true VE. The TBI code is based off of the ideal gas laws and quite frankly these motors or any motor is far from ideal, so you have to fudge some numbers to make everything work correctly. We try our best not to fudge them too much, it seems to keep the ECM the happiest, but a little won't rock the boat. Your on the right path, I can't wait to see how well it runs once you get it to quit blowing fuel out the exhaust.

DM91RS

I thought that you had a WB?

BMmonteSS

I do now, I didn't at the time. It would have been about a 5 minute problem instead of a couple of week problem if I would have had one.

flaming-ford

iTrader: (7)

sweet thread great info, can't wait to start tuning mine.

DM91RS

That's cool BM . I thought that I'd even talked with you about the ZT. I'm just about to bite the bullet and buy one. I quess the only issue that I have is having to deal with a serial to usb converter. People seem to have issues with those at times. My Moates box (ALDU1) has had zero issues. I wished that I could use it with the ZT-2 as a standalone unit.

DM

91RockS

Bron, I've read through that thread many times and I'd have to say it's probably the most enlightening thread I've read on overall tuning. I go back and read it quite often because I learn something new each time. BSmonteSS - can't thank you enough for that post.

I went back and checked my "PE - AFR at WOT" table. The values I posted are correct. I went back and looked at several other stock AXKW bin's I've downloaded and they all have the same rpm/afr table values I stated earlier. Is it possible that our XDF definition files are different? I'm using Jon Prevosts "61 for 8746_TBI.xdf" I'm tuning the WOT stuff pretty much like Dewey explained. One or two more iterations and I should have the WOT stuff nailed.

I've been meaning to spend the time to get PW into the datastream. I haven't tried any hacks yet, but I'll get to it. I'm just wondering how useful this is since the baud rate of the C3 is so slow. Do you really get many datapoints for instance if you datalog while doing WOT blast??

One thing I'd recommend to the tuning newbies . . . To really see what your total VE looks like, you need to add the two together and graph them (I used excel). TunerPro only graphs each independently, so you don't get the whole picture. Everything started making sense to me when I graphed out total VE.

91RockS

DM - The ZT-2 is great. To install the WB02, I pulled out the cat and made a custom Y pipe. The O2 bung is at the inlet of the Y. The Y pipe fits in exactly the same way the cat did (same inlet/outlet flanges), so I can reinstall the cat in just a few minutes if necessary. The pipe has a dump cap on it so I can go wide open by just taking the cap off. Haven't tried this yet, so the neighbors still like me!!

I tapped into the TPS, MAP, and RPM signals going into the ecm and wired them to the ZT2. The only trouble I'm having is that my MAP (boost) data goes off scale at min and max. I'm building a simple voltage reducer that should fix this. I have one channel left (the "user defined" 0-5 volt input) that I plan to bring in the ESC signal. That way I'll be able to pick up knock in my datalogs. I plan to do this before I start tuning spark advance. The datalogs from the ZT2 are invaluable since the sample rate is about 60 Hz, so the data resolution is excellent. I wish all the ALDL info was coming in at this rate. EBL should cure that, right??

As far as bolt-on's go, you're right. I'm trying the milk every last drop of performance out before I dig into the motor. Last year I ran a 15.5 sec quarter with just the exhaust mods. Since then I've added the 3.73 rear end and started tuning. I think I picked up .3 or .4 with just the gears. Next up is smog delete and 1.6 rockers. I'll be surprised if I don't drop into the 14's with all of this and a good tune. I'll find out in April when the track opens!

91RockS

I've done more tuning and datalogging since my last post. BLM's are looking real good. Now I'm working on fueling at WOT. For the time being I've got the commanded AFR at WOT set at 12.5. AFR measured on WB02 is pretty close to 12.5 at WOT since I cleaned up the VE2 table, but what I notice is a lean spike of about 15.5:1 at each shift point. It takes about 1 sec for the AFR to come back down to 12.5 as the engine accelerates. I'm attaching a jpeg of a datalog which shows the lean spikes during shifting, hopefully it will attach to this post.

I need help getting rid of the lean spikes since I don't like being that lean at high speed and load, plus they can't be helping performance. My guess is that this can be fixed by adjusting the power enrichment "pump shot" parameters in the bin. I see two tables. One is "pump shot vs. differential tps" and the other is "pump shot vs. differential MAP". Looks like both tables add incremental pulse width based on how fast TPS or MAP is changing. If I increase the values in these tables can I expect to eliminate the lean spikes?

BMmonteSS

Your delta TPS and delta MAP tables are where you want to start tuning your pump shot. There is also a Asynch pulse width modifier that is based on RPM, since your pump shot is injected asynch this will let you modify your pump shot based purely on rpm. You'll notice in your log your 2-3 shift lean spike isn't as bad as your 1-2 spike. You can use the RPM table to even that out.

Your deffinately on the right track, keep up the good work!

dimented24x7

iTrader: (2)

Opps... Sorry shifty. Didnt see your reply when scrolling through the thread. If you would prefer to have it remain in the TBI forum, maybe RBob or 3.8 could move it back.

dimented24x7

iTrader: (2)

Ive always been a little on the fence about the PE SA. On one hand, its a pain to have, but on the other hand there are times when you may want to have less timing when not in PE. For instance, with a larger TBI or a manual, its easy to momentarily get to high MAP values without entering PE, which means that you could still be hovering around stoich when the transient high MAPs are present. The extra timing might not fly with leaner AFRs. Some minor tweaks can push the computer to use richer AFRs at high MAPs even when not in PE, but that may effect emmissions.

As a side note, with some of the newer stuff, you almost have to have the PE SA, as there is alot of things that the computer does with the timing to control the engine, and I would imagine the timing has to be a little on the conservative side when not in PE to give the computer adiquate room to make adjustments.

Its a relatively minor thing, but still worth thinking about IMO.

dimented24x7

iTrader: (2)

Thats the correct format for that table as a scaled RPM value is used for the lookup

RBob

iTrader: (1)

Moved on back to TBI board. With the '8746 ECM the TPS AE is lame, it is based on the delta TPS% over 12.5 msec. Makes it difficult to get any AE out of it. So add some down low in that table. Then move on to the MAP AE, just be careful to not drown the engine at low RPM's.

On the '8746 (and '7747) ECM there isn't an RPM based modifier for AE. There is a table for async injector vs. RPM. However, this is used to convert the sync PW to an async PW in case the ECM wants to go into async fuel mode.

RBob.

BMmonteSS

Oopps, I've been using that incorrectly, please disregard my above suggestion.

91RockS

RBob (or others),

So it sounds like I am on the right track by adjusting the differential TPS and MAP tables to eliminate the lean spikes during shifting. Can you help explain to me exactly how the lookup function of these tables work? I've attached a TunerproRT snapshot of the "pump shot vs. differential tps" and "pump shot vs. differential MAP" tables from an AXKW bin.

Let's use the TPS based table for example (the one on the left). The top row is 12.5% differential TPS and 3906 usec added. My understanding of what is happening here is that 3906 usec's of injection pulse width is being added whenever (the "whenever" part is where I need help) the TPS is changing at a rate more than 12.5% over some time interval??? I'm probably way off base with the last part of that statement, so please set me straight on these two tables.

Maybe I just need a basic lesson in pump shot to get my thinking straight. I believe the function of pump shot is to add an extra "shot" of fuel whenever the engine load is increasing quickly or the accelerator pedal is being depressed quickly. Thanks

RBob

iTrader: (1)

Hit this thread first:

https://www.thirdgen.org/techbb2/sho...=accell+enrich

Just note that the specifics are based on the '7747 ECM, not the '8746. The main difference is that the '747 has better AE routines, it is a truck ECM. The thread does have good info in it on AE in general.

The specifics on the '8746 ECM (a car ECM): The delta TPS AE is based on the TPS% delta over 12.5 msec. Yes, 12.5 milli-seconds. Very difficult to get any change in TPS over that short of a period of time.

The delta MAP AE is different. The MAP delta is created by lagging the MAP value. As such it is stretched out over a longer period of time. The amount of lag is controlled by a filter value. There are two of them, found at $226 and $227. The value at $226 is used if the coolant temperature is under the value at $225, otherwise the value at $227 is used.

A lower filter value will provide a greater volume and longer time span of MAP AE.

There is a table of AE PW's for each of the TPS and MAP delta terms. Every 12.5 msecs (80 times a second) a lookup is done on these tables (dependent upon the need for AE). The values are added together.

A third table is now used: AE compensation vs. coolant temperature (AE CTS comp) at $332. The value from this table is used as a multiplier to the TPS & MAP values. The end result is what is used for AE.

The AE CTS comp table typically increases the volume of AE.

To put it all together, let's say the car is at a stand still and the go pedal is romped to the floor. The TPS% goes from 0 to 100% and the MAP goes from 50 KPa to 100 Kpa.

First the TPS AE: it may have taken 200 msec to reach full throttle (how fast does your foot move?), which is 6.25% per 12.5 msec. So over the next 2 tenths of a second the TPS AE contribution will be from the 6.25% entry of the TPS AE table. Then it is done, no more TPS AE.

If your foot is really fast and it takes 100 msecs to reach full throttle, then over the next 1 tenth of a second the TPS AE contribution will be from the 12.5% entry of the TPS AE table. And, it is only 8 shots of fuel, once every 12.5 msec (80 times a second).

The MAP AE is better: as the MAP value is lag filtered the inital MAP AE table entry will be the 50 KPA row (100 KPa minus 50 KPa, the difference between the idle and WOT values). As you hold the pedal to the floor, this MAP delta is slowly reduced. How slow is dependent upon the filter value. A smaller value and it is reduced at a slower rate. So each time the code comes around (every 12.5 msec, 80 times a second) the MAP AE contribution is a little less.

However, it is still adding AE fuel each time around. Until it reduces to nothing. This can be as long as a second.

There are some additional AE terms from $21E through $221 that are used to qualify whether AE is required, and to double the MAP AE term when the TPS% is over a threshold. Then at $222 is the IAC opening fuel contribution which will also act like AE (and is handled in the AE routine).

RBob.

DM91RS

RBob............how is this handled/improved with your new code?

dimented24x7

iTrader: (2)

Cant speak for RBob, but in the later stuff, it gets alot more sophisticated.

In the earlier computers, the AE isnt very flexible. In the later computers, and I think the earlier truck ecms, the duration of the AE can be adjusted based on what the engine temp is. This allows for more AE at cold temps then hot temps. They also have MAT based AE corrections and baro AE correction for the TPS based AE. The MAP AE also changes. Its now syncronous, as apposed to the TPS AE, which is still asyncronous. The sync MAP AE is also more of a duty cycle as there is a table that corrects the AE based on what the RPMs are. In addition, all the cheesy little tables are replaced with larger ones to give more resolution. All of this gives more control over how the AE works.

dimented24x7

iTrader: (2)

Im thinking about integrating this into the advanced TBI topics sticky soon, so look for it there if it falls off the general board in the coming weeks and you want to post in it.

RBob

iTrader: (1)

A night and day difference. In a nutshell the EBL code has both MAP and TPS delta's based on filter values. The filter value is dependent upon the engine coolant temperature (2d lookup tables). There is still an AE vs. coolant compensation table along with a new AE vs. RPM compensation table.

The MAP AE and TPS AE tables are large. The delta TPS table goes to 50% with better granularity. This makes it easier to tune and provides for enough delta TPS% for large TB's.

The AE fuel is added to the sync PW (as opposed to being an async PW). This provides several benefits as not only is the engine smoother during acceleration, the true injector duty cycle is available to the tuner.

RBob.

DM91RS

Thanks guys............good info all around. I'm looking forward to seeing some of these improvements in the future.

91RockS

RBob

Your posts continue to blow me away with the depth of knowlege you have around the TBI code. Thanks for your feedback on this thread. I'm surprised you have time with EBL going prime time. I'll be PMing you soon to inquire.

I read through the AE link you suggested and the info in your last post. The AE stuff is making sense to me, I just need to start playing with it now. I looked at some of my WBO2 datalogs (which samples at ~60Hz) to look at how fast TPS changes during quick shifting (manual trans) while doing a 1/4 mile blast. Looks like when I get back in the gas after shifting, TPS increases from 0 to 100% TPS in about 105 msec, which is about 11.9% delta TPS per every 12.5 msec. So to tune out the lean spikes during shifts I'll start by adjusting the top two cells in the TPS AE table and probably the top cells in the MAP AE table and go from there.

You mention some MAP AE filter values at $226 and $227 that will affect the duration of the MAP AE. I have been using TunerProRT exclusively to modify my bins. I do not see constants in my XDF that will allow me to change these filter values. My understanding is that all constants, flags, and tables must be defined in the XDF in order to modify them with TunerPro. I simply downloaded this XDF and have only made a few simple edits to it, but I have no idea how to define a new constant or table. How important will it be to adjust these filter values? I'll have to do some more searching to find out how to define new parameters in my XDF.

One more question. I see there are quite a few tables and constants that have values for "high coolant temp" and "low coolant temp". What I don't see in my XDF is a constant that defines what the threshold temperature is to detemine low temp vs high temp. Is this the value you referred to at $225? Is this a universal value for all temp based parameters or does each temp dependent parameter/table have its own definition of high/low coolant temp?

Thanks

dimented24x7

iTrader: (2)

What??? No ego stroking for the rest of us coders?

Just kidding . The term at $D225 ($225 in the chip) defines the breakpoint for those two filter terms. At temps below that temp at $D225, the term at $D226 is used, at coolant temps above that the term at $D227 is used. Use care with the MAP filter terms, as I believe the filtered MAP is used for decel enlean as well if memory serves me correct. You may inadvertantly effect how it operates.

The best way to tell if you need more duration is to look at the AFRs while AE is in effect. If it seems to go lean after a short time no matter what you put in the tables, then you may need to strech out the AE more. Its not very flexible, but it works in a fashion.

In the one that Ive nearly reversed (early to mid 90's PCM, 50k lines of pain in the *** PID goodness), there are whole coolant based tables for the filter coefficients, which will undoubtedly make things more interesting. They also have entire tables for the AE vs. IAC flowrate, rather then just one term.

dimented24x7

iTrader: (2)

As far as the TPS AE went, one thing I do remember is that even the short burst is needed. I eliminated the TPS AE in the tables to see what would happen. It felt like I had a fly by dial up modem throttle. Id hit the gas, and nothing would happen at first. Then, a few 10ths of a second later, out of the blue, the car would just take off.

I have a feeling that at least some TPS AE is needed to help with initial manifold filling.

Dewey316

Yeah, the TPS AE is needed for the throttle response. You really have to start messing with it, to get a feel for how the two interact. the low-mid delta TPS settings can be a real pain. Just too much AE there, and the car will bog with very little throttle input, too little, and it seems like there is a delay between the pedal, and the engine responding.

I am very much looking forward to getting all my EBL stuff from RBob. Then finally I will be able to really nail down my tune, especialy in the AE department!

91RockS

[QUOTE=dimented24x7]What??? No ego stroking for the rest of us coders? . . . Just kidding .QUOTE]

Sorry guys, didn't mean to sell anyone short. Keep feeding all this great info and I'll keep a strokin'.

You guys have answered most of the VE and AE questions I had. If I get time this weekend I'd like to follow up with a few questions on Power Enrichment and Spark Advance. If I can get the SA tuning hammered out I should have all the basics covered (for now anyway).

Dewey mentioned getting his EBL setup soon. Any idea how many coins that will set a guy back?? I'm hoping it will be compatible with my Prominator.

BMmonteSS

PM Rbob he'll let you know.

91RockS

I swapped my factory 1.5 rockers last weekend with 1.6's. While I had things apart, I installed a 180* thermostat and ripped out the AIR pump, lines, and solenoid valves, and capped off the air tubes on my headers. Couple of things I need help with:

With the 180* stat, are there any temperature constants that need to be reset in the bin? The lower temp stat has changed normal operating temp of the engine, so I thinking the ecm needs to know this. Or maybe it gets taken care of by retuning the spark tables.

Will removing the AIR system cause any driveability issues? Is there anythning I need to do in the bin file?

Finally, after datalogging with the 1.6 rockers installed, I noticed all of my BLM's moved up from around 128 to about 134. This is what I expected since the engine should now be getting more air, so the BLM's moved up to add in more fuel. Makes sense. My total VE is almost at 100% near peak torque, so I decided I would increase the BPW to universally add in fuel everywhere, then go back and tweak the VE tables. I changed the BPW from 134 to 143 but didn't see BLM's move down much if any. So I increased the BPW some more up to 153. Still no significant reduction in BLM's, all still hanging around 134. This is driving me crazy. Shouldn't increasing the BPW to by 19 (from 134 to 153) have richened the entire fuel map up? I would have thought my BLM's would be down in the low 120's with a BPW of 153. One thing to note is that I have a Prominator, so I can flash in new bins on the fly without shutting off the engine, which is what I did. Do I need to disconnect the battery to reset the adaptive learning tables before datalogging after changing the BPW? Need help on this one.

Fast355

iTrader: (2)

The BPW needs to be set to your engine/fuel injector combo. To get more fuel you should raise your pressure, then change your BPW to match, then go after the VE table. You can't add more fuel if you are already nearly static.

BMmonteSS

That is strange that your BLM’s aren’t changing. I don’t think that you could be going static at part throttle (the only place BLM’s have any effect). I think it’s probably more likely that your fuel pump can’t keep up with the added volume, although it should still make at least part of your BLM tables richer. You may want to reset the ecm and try it again, also if your not clearing your BLM tables in winaldl then it will take a while for avg.’s to get skewed down to where they need to be.

91RockS

So I'm not mixed up about how the BPW works. If the ecm is adding in fuel everywhere (blm's are high) then if I raise BPW I shoud expect to see all the part throttle blm's go down.

Where are the blm's stored in the ecm, meaning do they get reset every time I update the bin, or do they get carried over? If they get carried over, then maybe I need to reset the ecm (disconnect battery) and try again.

BMmonte: Funny you menetion the fuel pump. Last year when I swapped gears in my rear end I dropped the fuel tank and installed a 190 lpm pump. Before the pump install my FP was running at about 12 psi. After installing the 190 pump the pressure move up to about 13.5 psi. This was with my AFPR at the lowest possible setting, so I couldn't get it any lower. Made sense since the pump is pushing more flow across the regulator so the pressure went up. Last night after datalogging and having the issue described in my original post about the BPW I checked FP. To my amazement, it was had dropped to about 9 psi. It's been a while since I checked FP, so not sure how long it's been that low. I adjusted the AFPR back up to 12.5 psi and did more datalogging. Still seemed to have the same issue with BPW not affecting blm's. I sure hope I don't have a FP issue, that woud suck dropping the tank again. I suppose one of the connections in the tank could have somehow partially loosened and is pissing fuel into the tank. Is there anything with the regulator I should check (like the diaphram)?

Thanks guys

RBob

iTrader: (1)

When the EGR is active there is a 12 line table of BPC's that is used. It is vs. manifold vacuum (not pressure). Table is at $2A1. Note this is for the '8746 ECM.

RBob.

RBob

iTrader: (1)

The BLM's are stored in on-volatile RAM. However, with the '8746 they are all reset to 128 at each key-on.

On the '7747 there is a min/max value used at key-on. These values are usually closer to the 128 then the normal running min/max BLM values. The BLM values will be brought to these values if greater or less then at key on.

RBob.

BMmonteSS

Hard facts from the man himself........better try disabling the EGR and see if that helps. Like Rbob said, when the EGR is enabled there is a table of BPC values that are used instead of the base BPC ( which coincidentally is called "BPC when EGR off" in the hack)