hmx

First, let me say thank you to all of the contributors on the boards here. I have not posted a lot, but I have spent many hours reading, and the insight shared here has saved me many hours of work and headache. I would also like to thank everyone for letting me post here despite not having a 3rd gen car... although I hope that the questions that I do post are universal enough to be applicable to third gen cars as well and might thus help others somewhere down the line.

Now, I must ask some advice: I swapped my engine from a 305 LO3 to a 350 LO5, and it has a TBI setup. I have an ANLU chip (8746 ECM), and, after reading here, realized that I was overtaxing my injectors (the car had no power after ~3000 rpm) and I replaced the standard 55 #/hr injectors with 80 #/hr injectors (actually tested at 79.6 #/hr). I figured too big was better than too small. Not surprisingly, running the stock ANLU chip, the car runs very rich (many of the BLMs are bottomed out at 108). I wanted to change the BPW to make the gross fuel correction, but I'm coming up with a BPW of 104, which is pretty small. I wanted someone to double check my math here to make sure that I'm not going to lean out the engine horribly. Admittedly, it makes sense that the BPW could be this small with injectors that large on a 350, but I'd rather make sure that this even makes sense before I reprogram it into the ECM. Oh, and the fuel pump is stock, no changes there.

Using the conversion from BMmonte's 'come in for a free tune' thread...

350 ci displacement = 5.74 L
5.74 L / 8 cylinders = 0.717 L/cylinder

79.6 #/hr / 3600 s/hr = 0.02211 #/s
0.02211 #/s * 453.6 g/lb = 10.0296 g/s

BPW = 1461.5 x (cylinder size (L) / fuel flow rate (g/s))
BPW = 1461.5 x (0.717 L/cylinder / 10.0296 g/s) = 104.48


Does this seem like it's in the ballpark?

RBob

iTrader: (1)

Your BPC calculation is correction, for when EGR is off. There is another table of BPC values for when EGR is active. Just use the ratio of the original BPC to the new BPC for the tables new values.

You should also adjust the AE PW tables and the Proportional gains tables by the same ratio. Although they both will likely require additional tweaking for the best in drive-ability.

RBob.

hmx

Thanks for the info! I hadn't realized that there was an entire table for the BPW/BPC when the EGR was active (probably because most people deactivate it and thus there is little discussion of it on the threads here). I'll make sure to modify the constants on the table as well. Glad I asked!

hmx

RBob, I appreciate all your help. I looked through old threads, and you told 91RockS that the table to look for, containing the BPC modification when the EGR is on is a 12 line table at location $2A1, and was vs. manifold vacuum.

I have looked through the disassembly, searching with the $2A1 string, and cannot find it. There is only one line that contains $2A. If I use any of the Jon Prevost xdfs, the table does not appear. If I use the generic $61 xdf, the table does appear, but many of the other aspects of the constants and tables are changed--mostly there are less tables to edit. Is there a way to reconcile these two, perhaps by adding the BPC table for when the EGR is on to the (I assume later) Prevost xdfs (61v2.xdf, 61v3.xdf, etc.)? Can I just create a new parameter in the xdf and add this table in by copying the data from the other xdf, or is this going to conflict with some data in the prevost xdfs?

Just FYI:
ECM: 8746
BIN: ANLU5369 61.bin
ADS: 1228746 - 160baud.ads datastream defintion.

I am going to do some more reading on the AE/PW tables to make sure that I'm adjusting them correctly (I assume you mean the AE PW, the AE pump shot, and the AE Wall wetting tables?)

RBob

iTrader: (1)

The table starts at $2A1, with a 1-byte header the data starts at $2A2. Need to look for a table definition at $2A2 in an XDF file.

It is best to create a new entry in the XDF via Tuner Pro. Mark states to not hand edit an XDF file.

AE: there are two tables to change, one is delta MAP based PW, the other delta TPS based PW.

RBob.

hmx

Ah ha, I was looking in the disassembled bin file, not the XDF! I'll make sure to edit the XDF in TP only.

The two AE tables you speak of are clear in the $61.xdf, but are listed as "Pump Shot vs. Differential TPS" and "Wall Wetting vs. Differential MAP" in the prevost 61v2.xdf (for anyone else reading this thread). There is also a third AE table in the prevost def, "PW mult vs. Engine Temp". Since it is a multiplier and not a scalar constant (such as the microseconds on the other two AE tables), I assume we can leave it alone?

And, as for the tables themselves, my BPW went from 135 to 105 (77.77% of what it was). Thus, I assume that I should multiply the microseconds in the AE tables by 77.77% to obtain the new values? For example:

Old table:

New Table (77.77% of what the old one was, to preserve the ratio of new BPW to old BPW)

Once again, thanks a ton for all of your help and replies! I can't express to you what this forum owes you.

RBob

iTrader: (1)

You have it.

RBob.

hmx

Outstanding! Thanks again!