I ran my best ET ever with a 12.127 sec (60' 1.735) at 110.55 mph tonite @ Milan Michigan. Also, what was very interesting is my 3.5" MAF sensor & experimental air lid that I built myself. With factory MAF & air lid my best time was 12.277 sec (60' 1.800) at 110.35 mph.

Looking at the 60' times, this can explain the drop from 12.277 sec to 12.127 sec,,, so I have a bit to think about. I do know that the max engine load was 175 for the 3.5" MAF, while the factory MAF & air lid has an engine load of 254.

I did not run my wide band O2 sensor at the dragstrip. However, I know that at 52psi (where the engine seems to run the strongest with the factory MAF), the wide band O2 meter reads 12.0 to 12.1 at WOT.

The 3.5" MAF flows about 38% more air. With the bigger MAF though, the electronics is not picking up the actual air flow (as expected),, so I faked the ECM out (which I dont like to do, against my priciples) by using an inj constant of 17.5 #/hr. The 17.5 inj constant gives the nearly the same BLMs while cruising around as the factory MAF did with a fuel constant of 22.5 #/hr.

I would strongly prefer to modify the MAF tables to read correctly, however I have only ever used TunerCat ( I cant go above a specific value in each table). Is it true that TunerPro will allow me to fully adjust the MAF tables by changing the max allowable value at the top of each table?

I think with the 17.5 inj constant along with incorrect MAF tables is resulting in the engine load factor of 175 and maybe limiting how much fuel that I can get into the engine.

Any comments, please. Edit: 165 ECM $6E def & highly modified ARAP bin.

BTW: In June, I was running 113.5 trap speeds, so I am concerned about the 3 mph drop,,, I cant explain it right now. The June runs were run with the factory MAF & air lid.

Rest of engine config is in my sig.

 

What was the ambient temp. from the run tonight compared to the previous quickest run?

 

DON'T fix the airflow tables, actually. Otherwise you'll just hit the 255 g/s limit, and be back in the same boat as before. What you did was the correct way, by fudging the injector constant. The ECU doesn't know or care what reality is. You could simply go into tunerpro's xdf and change the multiplier for injetor constants and make a new multiplier to un-fudge the airflow if you want. Then look at all the old airflow values at each airflow, and remake the same values but at the same DISPLAYED airflows (although fudged internally).

So in essence, your car can probably flow a REAL 280 g/s, but your MAF using the OLD airflow to voltage MAF tables shows 200 or whatever. You can use the XDF to make 200 appear as 280, but inside the ECU, it's just bits and bytes, with a limit of $ff. No need to let the ECU know that you're really flowing 280 g/s.

 

What kind of maf sensor are you using?

 

Have you considered using one of the digital converters and LS1 MAFs? You can adjust the injector constant so that the flow in the MAF table represents something other then 0-255 gms/sec.

 

45 degrees last nite, 55 degrees last June.
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What kind of maf sensor are you using? I started with a stock MAF and cut away the plastic tube part, and simply mounted in a square hole which was cut out of the side of a 3.5" aluminum tube.

Have you considered using one of the digital converters and LS1 MAFs? I know nothing about digital convertors. I went the route that I know the most about.

 

RednGold86Z: Good comment. I have been thinking that maybe I have run out of fuel. I went all the way up to 58psi on my last run and thats when I turned the 12.12 sec ET and remember to hit the scan bottom. In checking the scan, thats when I noticed only 175 for engine load. At 4274RPM, the PW was 10.8msec. MAF flow was 160 gms/sec. So maybe, I did run out of fuel. I should go to 30s or 36s.

 

Im using an LS1 MAF with its signal fed into a PCM. Other then its large size, which can hinder idle a bit, the LS1 MAF seems to be quite accurate. The overall accuracy of the MAF and PCM actually exceed that of the injector driver hardware. There are some digital converters available that will convert the MAF frequency to a voltage, and even allow you to scale the conversion so you can optimize the accuracy and flow range that your ECM will be able to see, which can really help with an 8 bit system, which has extremly coarse resolution. The LS1 MAF is also definatly an upgrade from the stock garbage MAF that they originally came with.

Also, from what youve posted, those MAF flows look low. Its likely that the MAF will be able to see over 255 gms/sec now that youve gutted and enlarged it. The actual voltage wont increase, but what it represents will. IOW, the 160 gms/sec you now see is likely to be around 230 gms/sec or so of actual flow.