flow-matching MAF to modifications...
04-14-2003, 09:52 AM
#1
AudiWorld Super User
Thread Starter
flow-matching MAF to modifications...
<center><img src="http://pictureposter.audiworld.com/711/bleedport1.jpg"></center><p>
Here's a few pics of the MAF being altered to allow more air in the sampling tube so it can catch up with the additional air going thru the body now that the screen is removed.
I started with a drill bit that is .040" then test-drove the car with an air/fuel meter attached then repeated with drill bit sizes; 041", 042", 043", 046" and .052" which is where my air/fuel numbers came back up to where they were prior to screen removal. Pics are of .052" bleed orifice. Cars is noticeably quicker, even more eager to climb in the RPM's as well as significantly enhanced throttle response. But I haven't done any timed runs yet.
Next up is to grind the screw housings down in the sampling tube downspout and smooth and radius them so the air is not disturbed more than necessary as it enters the maf and sweeps past the sampling tube column. Then fill the tapped half-hole remaining with epoxy and sand smooth. Then try to catch up to the extra flow of that modification by again drilling incrementally larger holes. At some point I'll max out the margins that are calibrated into the MAF electronics which will either send the MAF into a hissy fit, make the car act funny/weird or stop enrichening at WOT at which point I'll stop and live with it till I can get the MAF re-calibrated and remove the center cross beam altogether. No codes or CEL's logged throughout any of this... yet.
When I first drilled the .040" hole this morning nothing happened and I couldn't figure why. Then it dawned on me to chamfer and polish the hole on inlet and outlet side. Voila! Instant change!
I'll post a follow up soon as I've arrived at the point of diminishing return.
Oh and I know you're wondering how I'll attach the backing plate once the screws are removed and their stand-off holes ground down flush. Easy... small bead of epoxy on the underside as it never has to be removed again no matter what the outcome of any of this.
Here's a few pics of the MAF being altered to allow more air in the sampling tube so it can catch up with the additional air going thru the body now that the screen is removed.
I started with a drill bit that is .040" then test-drove the car with an air/fuel meter attached then repeated with drill bit sizes; 041", 042", 043", 046" and .052" which is where my air/fuel numbers came back up to where they were prior to screen removal. Pics are of .052" bleed orifice. Cars is noticeably quicker, even more eager to climb in the RPM's as well as significantly enhanced throttle response. But I haven't done any timed runs yet.
Next up is to grind the screw housings down in the sampling tube downspout and smooth and radius them so the air is not disturbed more than necessary as it enters the maf and sweeps past the sampling tube column. Then fill the tapped half-hole remaining with epoxy and sand smooth. Then try to catch up to the extra flow of that modification by again drilling incrementally larger holes. At some point I'll max out the margins that are calibrated into the MAF electronics which will either send the MAF into a hissy fit, make the car act funny/weird or stop enrichening at WOT at which point I'll stop and live with it till I can get the MAF re-calibrated and remove the center cross beam altogether. No codes or CEL's logged throughout any of this... yet.
When I first drilled the .040" hole this morning nothing happened and I couldn't figure why. Then it dawned on me to chamfer and polish the hole on inlet and outlet side. Voila! Instant change!
I'll post a follow up soon as I've arrived at the point of diminishing return.
Oh and I know you're wondering how I'll attach the backing plate once the screws are removed and their stand-off holes ground down flush. Easy... small bead of epoxy on the underside as it never has to be removed again no matter what the outcome of any of this.
04-14-2003, 10:40 AM
#4
AudiWorld Super User
Thread Starter
No, standard MAF but with screen diffuser attached to sampling tube only...
with stock screen removed and I plan on small, gradual removals of the center column until I can't adust for it by mechanical means any longer.
Just because the MAF screen is removed doesn't mean the sensor wires are sensing correctly since that air no longer has a way of being smoothed out and stabilized. And just because it doesn't throw a CEL or log a code still doesn't mean everything is working ok. Just means it hasn't stepped out of "margins/parameters" yet. Having a screen in front of the sensor wires should help get those wires smooth, stable air so the MAF can be more precise in it's samplings.
Just because the MAF screen is removed doesn't mean the sensor wires are sensing correctly since that air no longer has a way of being smoothed out and stabilized. And just because it doesn't throw a CEL or log a code still doesn't mean everything is working ok. Just means it hasn't stepped out of "margins/parameters" yet. Having a screen in front of the sensor wires should help get those wires smooth, stable air so the MAF can be more precise in it's samplings.
04-14-2003, 11:12 AM
#7
AudiWorld Super User
Thread Starter
Autometer Phantom series...
With stock setup before TB and MAF inlet I was seeing 2 full green bars and an intermittant 3rd bar in the "rich" area with MAF screen installed at WOT.
With TB , MAF inlet and screen removed I was getting only one intermittent green light.
With screen in it went to 1 solid green and one intermittant green at WOT.
After MAF screen removal and installing the sampling tube screen I was seeing all solid yellow lights in the "stoic" range with an intermittant single green in the rich area. With where I'm at now I'm seeing 3 soild greens in the rich area. I can't find my graph that came with my gauge right now to tell you what those lights represent mili-volts or ratio-wise.
When I'm finished I'll hook up my Fluke 86 Automotive Meter and tell you what those numbers are as it uses "dampening" software to average the readings. Otherwise they're too eratic in any mode other than WOT. The Autometer is what I use for many repetitive runs as it gets me in the ballpark with at-a-glance readings. When fine-tuning I swith to the Fluke.
With TB , MAF inlet and screen removed I was getting only one intermittent green light.
With screen in it went to 1 solid green and one intermittant green at WOT.
After MAF screen removal and installing the sampling tube screen I was seeing all solid yellow lights in the "stoic" range with an intermittant single green in the rich area. With where I'm at now I'm seeing 3 soild greens in the rich area. I can't find my graph that came with my gauge right now to tell you what those lights represent mili-volts or ratio-wise.
When I'm finished I'll hook up my Fluke 86 Automotive Meter and tell you what those numbers are as it uses "dampening" software to average the readings. Otherwise they're too eratic in any mode other than WOT. The Autometer is what I use for many repetitive runs as it gets me in the ballpark with at-a-glance readings. When fine-tuning I swith to the Fluke.
