While road testing my '87 IROCZ with my eprom, the BLM is 158 and the INT is 128 or sometimes higher like 142.

I have increased the fuel map by 20% over stock, but it seems to have no effect on the BLM.

The lower part of my fuel map is:
16 gm/sec: 0.76msec for injector pulse
32.........1.37msec
48.........2.14msec
64.........2.67msec
80.........3.20msec
96.........3.81msec

What are you guys doing for injector pulse width at the lower end?

Please check my mods in sig. TIA.

Doc



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'87 L98 TPI IROCZ, AFR190 heads, 3.70 gears, ZZ9 cam, 3000 Art Carr TC, SLP 1 3/4" headers, SLP cat-back, no cat, no AC, no MAF screens, Accel manifold base & SuperRam, 24#/hr SVO injectors, Edelbrock double roller timing chain, MSD ext coil & distributor, trans cooler, 52mm TB with airfoil, TB coolant bypass, AFPR(50psi), K&N filters, Hotchkis lowering springs, my custom chip, Lay Ind. ram air kit, SS Brakes 1LE upgrade 12" rotors dual piston calipers, 265/45R16 Kumho V700 tires.
ET 13.27sec @ 103mph on MT ET Streets
'90 Eagle Talon AWD, no rust thru 9 winters
'99 Camaro SS, red, 6-spd, T-tops, Mcleod clutch, Pro 5.0 shifter, MAF processor, Direct Flow airlid, K&N filter, next mod: 4.10 rear gears
313.7Hp & 320.6ft-lbf, ET 13.55sec @ 105.1mph

 

First, I would look at "playing" with my Injector Constant...lower constant will richen it and higher constant will lean it.

You want to strive for an injector constant that will bring you as close as possible to 128/128 for the majority of settings.

Then you may find you have to "tweak" the MAF Scalar Tables. If you find that you are running overall lean, then raise the various gm/sec flows in the varous MAF tables using your Diacom readings as a guide (ie. if you are running a bit lean at 32 gm/sec, then raise the number in the corresponding MAF Scalar table.

Now, here is the tricky part; you may find that when you get to the upper part of a MAF Scalar table, that you cannot increase it anymore due to the corresponding number translating to x'FF in the eprom and thus you cannot increase it anymore. This x'FF limitation happens in EACH of the 6 MAF Scalar Tables. Then you have to purposely richen the overall mixture by using a lower injector constant and then "recalibrate" all 6 MAF Scalar Tables so the upper flow can be handled with x'FF.

Conversely, you may find the lower value of the MAF Scalar table cannot go any lower. This will seldom be hit except in the lowest part of MAF Scalar #1. Most of the other MAF Scalar tables use a number around d100-150, so there is more ability to recalibrate them to flow a lower number. But it is theoretically possible to find yourself getting too low of a value to the lower part of the MAF Scalar table.

The point I have to emphasis is that this x'FF limitation doesn't only happen at the upper flow of the MAF, but at the upper boundary at EACH of the 6 MAF Scalar Tables. MAF is great, until you need to start fiddling with those MAF Scalar Tables. Then it is not so great.

[This message has been edited by Glenn91L98GTA (edited September 25, 2001).]

 

Where are you lean? During acceleration? Way back when my car was a 350 and still running the 165, I had problem with going way lean after I put on a Super Ram. At that time I did not burn my own chip but had Ed Wright do it for me. The other funny thing was I only went lean in first and second gear. Playing with MAF tables only made things worse. The solution was to lower PE enable from 70% to 45% and that covered up the lean spot. Have you verifed fuel pressure during the lean time with your gauge taped to the windshield? Usually with the 165, you only need to fiddle with the MAF tables if you ported your MAF. Even then usually only the idle areas need adjusting. As far as the max limit, as you know, PE vs RPM takes care of that.

I have a buddy that has figured out a way to increase the air flow measuing ability of the 165 MAF to about 330 gms/sec instead of 254. He has spent many hours perfecting it and claims it works.

 

Glenn and 89vette,

Thanks for your responses.

My fuel injector constant is set at 26#/hr.
I set it at that value because the 24#/hr SVO injectors on the GM scale will actually flow about 26#/hr due to the fuel pressure diference between the Ford and GM stuff.

OK, as opposed to continually increasing the bottom part of the fuel map, I will change the fuel injector constant to 24#/hr, and do some more on road tests.

I am running lean during cruise around driving (normal city driving), not WOT. During city driving the BLM is 158 and the INT is above 128 but that value moves around a bit.

At WOT, I'm running about 830mV on my XP240 scanner. I dont have Diacom. At 830mV I am a little lean there also. I will work with the WOT tables to bring 830mV up to 860mV on the O2 sensor. This is where my car runs best at WOT.

 

I agree that lowering your injector constant is the first step, especially since you're also lean at WOT as well as part-throttle. I have my constant at 25.0 lbs/hr for my SVO injectors, giving me BLM's of 128 in most of the BL cells that I care about. Changing the fuel map won't do anything since it isn't used.

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Greg Westphal
'87 IROC 355TPI/A4

 

hey, Greg,

I have seen BL cell 6 and 9 (I think) on my scanner when the BLM was 158.

Can you explain what the BL cell are? I dont know anything about those. Are there different cell numbers for each column I see in my fuel map? (such as 16 gm/sec and 32gm/sec, etc.)

 

I am really starting to re-think my eprom burning strategy, especially towards the Injector Constant.

My buddy with a 383 Miniram, AFR heads etc, STILL running MAF (we are exploring how far we can go with it), are finding similar things. I am now taking the approach that the "rated" flow, is just that "a rating" to use as a "starting point".

With MAF, we are finding the best approach is to adjust the Injector Constant so that the engine is NOT running lean at ANY of the "upper settings" on any of the six MAF Scalar tables. Then, recalibrating the MAF once we are assured that NONE of the upper boundaries are over 255.

If, after all this we STILL go lean on MAF Scalar Table #6; this represents the MAF maxing at 255 gm/sec. Currently, it is looking like we max out at 5,000 rpm. SD is most likely the next modification, after we have fully explored MAF.

[This message has been edited by Glenn91L98GTA (edited September 25, 2001).]

 

I have a buddy that has figured out a way to increase the air flow measuing ability of the 165 MAF to about 330 gms/sec instead of 254. He has spent many hours perfecting it and claims it works.

[/B][/QUOTE]
so how????? Please share!


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86 406

 

Driveit,

That's his baby not mine. I'll be on vacation until 10/3. Whan I come back remind me and I'll contact him to see if he will allow me to share in his findings. It really is a great idea and a simple one at that.

Jason

 

There are 16 BL cells, divided up by RPM and airflow (grams/second). The boundaries in the ARAP bin are 700, 1200, and 2000 RPM and 12, 22, and 34 gps. With RPM on the X-axis and airflow on the Y-axis the numbers go across each row then up to the next column. So, the bottom row has BL cells 0, 1, 2, and 3 for airflow at/under 12 gps and the 4 different RPM ranges. BL 6 has and RPM range of 1200 to 2000 and an airflow range of 12-22 gps, while BL 9 is between 700-1200 RPM and 22-34 gps.

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Greg Westphal
'87 IROC 355TPI/A4