Bout 101 IIRC, but that doesn't mean the other 100 are correct :muahaha:Quote:
Originally Posted by Redline Motorsports
And when it comes right down to it, it's either 1 or 0 :Eyecrazy:Quote:
Originally Posted by Redline Motorsports
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Bout 101 IIRC, but that doesn't mean the other 100 are correct :muahaha:Quote:
Originally Posted by Redline Motorsports
And when it comes right down to it, it's either 1 or 0 :Eyecrazy:Quote:
Originally Posted by Redline Motorsports
I get the AFR's where I want them in SD mode by tuning the VE. I then tweak the MAF by percentage so that the AFR's match no matter what mode the car is operating in. Most of the time I don't have to change the curve, just add or subtract a percentage of the whole curve.
I also tune Ford EEC's and In the Ford system they rely on the MAF for fuel and load calculations for timing adjustments. For that reason the only correct way to tune a Ford is by MAF adjustments. I use the same prinicples on both Ford and Chevrolet to make sure that the vehicle is thouroughly tuned.
EFILive is great and I use all available tables that I need to make the adjustments that are needed.
Very interesting thread guys. I must say that from a noob's point of view, its very enlightening. Definitley worth a read.
Yeah it is interesting. So if I took thoes little tubes that direct airflow into the airbox I probably just messed with the Maf. I have a truck so nobody probably knows what im talking about, but its a tube gm put in the inside bottom of the airbox.
The latest Hitachi sensor is a marvel compared to the old bare wire clunkers in the foiled, screened housings. The new sensor is shielded from reversion and lots smarter. I talked to the GM PCM guys @PRI and they caution on proper placement in the air stream, but are betting the ranch (and the LS9- check out the MAF table for the 08 LS3) on MAF technolgy to to produce predictable emissions (AFRs).
If you watch your fuel trims trying to second guess a maffless tune, it is indicative of the problem. Have watched my carefull prepared SD tune go to hell in the course of a summer evening at the track. Temps drop 25*, humidity changes, and the tune drifts further from reality. Not to say a "right on" SD tune is not great but, if we all lived in Honolulu it would be a different story, and crowded.
hey Bruce, how can MAF be shielded from reversion? isn't the whole idea behind MAF that air goes through/around the hot element, which requires you to have both ends open? could you elaborate a bit?
A few pics> LINKQuote:
Originally Posted by redhardsupra
I was in the process of tuning my MAF after switching back to a stock op system and the whole feeling of the tune felt terrible. I was throwing various codes, it was getting high KR and in general was running terrible.
There's so much info on here....it's sometimes hard to work out which way to follow.
I asked a buddy of mine who works for GM how they go about setting up the their base tunes and dialling it all in.
This is a reply I just got from him.
Quote:
Checking the MAF frequency and changing the curve to suit should work. I have actually done this once before to improve emissions in an early experimental HSV engine (new air intake completely changed the airflow characteristics). Normally it would be done on a proper test bench with the entire air intake setup - but that isn't going to be easy to do in your case.
A real quick and dirty way to do it is to see how much your fuelling is compensating (for example, -12%), and just pull out 8% or so from the predicted airflow in your MAF curve . If the fuelling heads the right way, then chances are you are on the right track. From there you can fine tune each frequency point as required.
The MAF curve is obtained by testing the entire intake system with the MAF in it, not just the MAF itself. That alone indicates that the intake plays a part in the MAFs response to airflow changes. Otherwise we would just get a curve from the MAF manufacturer and use that.
I'd imagine that the difference is due to changes in airflow/reversion etc around the MAF depending on the geometry of the intake.
As an example: We had a car a while ago that all of a sudden would hardly idle. After some investigation, it was found that a thermocouple had been placed in the intake, about 4 inches in front of the MAF. That was enough to make the airflow so turbulent in the MAF that it was getting airflow swings as high as 50% at steady state.
Basically the MAF behaves like a waveguide with constant+alternating (DC+AC) pulses (waves) going in both directions (interfering with each other to create high/low pressure nodes) and being very dependent on the physical geometry... if you change something in the tract or the motor, then the MAF calibration is wrong...
Thanks Joe..yeah...alot of people say "don't touch the MAF it's a calibrated instrument".
Well for me..this kinda proves it's the (one of) right way to go.