BLM's

[FTA1995]

OK, so as some of you know, I had a wonderful escapade with one of those granatelli MAF sensors, long story short, I hocked it in frustration and went with a 5 pin Delphi with screen/fin intact etc. Definitely helped correct some of the surging issue. I also replaced my O2's with two Bosch pn#15703. Now it seems no matter how I alter any systems I'm getting a consistent BLM of 108 on both sides. For reference, before I swapped the MAF's, with the granatelli I was getting about 138-145 BLM's. If anything, I'm starving my motor of fuel, definitely not running rich. I did find a post by mr Injuneer in here somewhere, checked everything, flow rates appropriately calibrated for the change in fuel pressure, good working fuel pressure regulator (no damaged diaphragm) O2 harness(es) are not suspect as the BLMS weren't split with the other sensor.
It IS possible that these injectors might be leaking; they're old, beaten on and probably have pintle seat wear. They do not exhibit any visible form of leaking though... I originally thought the low BLMs were due to my timing advance at any given rpm or kpascal, but every timing combination I had time to do had zero effect.

Ideas? I have been reading about this wherever information is given, checked all the possible causes I could think of.

[FTA1995]

AND I am using a Delphi 3 to 5 pin converter for the MAF, looks like the 5 pin just includes an IAT thermistor onboard (?) for the extra 2 pins.

[Injuneer]

Why did you opt for the Bosch O2's? Most people who have used them have negative feedback. OEM AC/Delco (Delphi).

Is it possible you have O2 sensor harness problems?

You indicate you verified the signals from the MAF - does that include the output signal frequency?

[FTA1995]

Yes there are negative reviews in most places I've seen, but I did swap in a set my friend had, I don;t remember the part numbers, but I do remember they had circular openings instead of the slit type, what I did was take a flat head and just pry the slits open carefully until I got within 1 blm count of the other sensors on the old MAF, seems like these just suck on longtubes because of the distance to the O2 bung from the head compared to stock... They seem to be working as they should now. Same friend who lent me his O2's swapped mine into his system to see the difference (he doesn't have anything except a K&N CAI) looks like the bosch parts read the afr to be a bit richer until you open them up a little, given the difference on mine with longtubes was much higher. The harnesses are still checking out ok.

BUT the 108 blm problem is gone now, I was unaware that by switching to the 85mm obd2 mass air, the sensor put out a different freq. per g/s than the earlier GM models, assumed it didnt since you could simply buy a 5 - 3 pin adapter from GM.

The best advice I can give to everyone, at least for an lt1, NEVER waste your money on a granatelli high flow sensor, you'll never be able to get the calibration right, and it will give you nothing but crappy tunes and lean out everything. I know this has been said a great many times be many people, but I can't emphasize this enough now from my experience.

[Injuneer]

I wouldn't be prying on the O2 sensors with a screwdriver. Its just the shield, but it isn't going to take much to bust the sensing thimble inside. The best thing to do is just buy the correct sensors.

[FTA1995]

definitely will do that instead next time, but I couldn't argue with the price on these, I think they might be kind of a crap shoot and I just got lucky