VAP

<center><img src="http://pictureposter.audiworld.com/711/boredmaf.jpg"></center><p>
Her's a pic of my MAF as it exists right now and the post of the strange tale below: As you can see all the way to the paper filter element this thing is BORED!

I posted the other day that my car runs fine with the MAF unplugged if started after the neg battery terminal has been disconnected a few mintues.

Well after discovering that I decided to test run a spare MAF housing I have lying around by boring it out. I'm not talking hacksawing the sampling tube and leaving the inlet sampling tube or any of that stuff. I'm talking clamping it to the milling table and BORING THE MAF HOUSING!! Nothing remains internal in the MAF. When I reinstall the control module it's wire sensor housing is the ONLY thing remaining in the tube... nothing else... zero, nada, zilch, bupkus. And after installing it and reconnecting the neg battery terminal I start it up. No surprises here... I have a CEL within 3 seconds of starting. But fuel/air module readings are good, O2 sensors reading normal, and timing modules check out ok. I then take it out for a drive being very careful to monitor all telemetry. Everything seems normal 'cept that pesky CEL on. Drive it fast, slow, stop n go, city streets and interstate. Runs great, I mean better than it's EVER run! And all telemetry is giving me green light feed-back.

I put 22.5 miles on it then pull over to the side of a convenience store and pull codes. Here's where it gets very very strange... Twilight Zone kind of strange. My VAG 1551 tells me "no DTC's recognized." Damn thing has no codes to recognize, let alone clear. This can't be I'm thinking. I should have a ton of codes and the CEL was on full time the whole trip! So just to complicate things even further I restart the car. No CEL this time. I'm thinking WTF!?! So I drive home. On the way I'm *****-footing it, hammering it and just driving the dog-poop out of it trying to get a code... nada. Car is behaving beautifully all the way home. Now out in the garage I pull codes again. Again nada. Car is faster than blazes, and even the MAF units output voltages are within spec for a stock car. From 1.35v at cold idle, 1.65v at warm idle, 3.35 at WOT blips while in neutral and 4.85v at load. Perfect numbers. I should say "perfect numbers for a car with a stock MAF. And apparently on a car with a totally gutted MAF. Timing tables: same thing. Actual fuel/air ratio gauge settings at idle and WOT on the highway: perfect! Timing: perfect. I'm completely stumped.

Now as good as all this sounds I don't think if I was sitting on you guys side of the monitor I'd rush right out and try duplicate this. I mean it's entirely possible this is a fluke and I got lucky, nailed an idyllic situation right outta the chutes, completely inadvertantly and entirely by accident. But there remains the possibility that maybe this will only work at altitude or a myriad of other possibilites. So don't take this post as encouragement, endorsement or advocating on my part cuz it's none of those. It's merely my passing on an inexplicable situation that has positive benefit but remains a mystery, least for now.

Mr.D-'97 A4q 12v

Very interesting. Good work!

Audiboy

that's weird. What's VAG 1551 anyway? Maybe we need to use your ECU for S/C development :P

SlammedA4

I am pretty much at sea level and I have done a lot of mods to my motor. I would be MORE than willing to be a beta test for this project. What are your thoughts?

MikTip

<center><img src="http://pictureposter.audiworld.com/6607/mafcut.jpg"></center><p>

VAP

I have Ross Tech software/cable too but the VAG factory unit is completely self-conatined in a blue plastic 8"x5"x2" box w/fold-up lid, 1/4 the weight of a laptop and easier to take along. They were $1500 5 years ago. You can still find em around at most dealerships service departments. The new 1552 is about $3500 and has all the OBDII updates. The 1551 had an Audi/VW part number and was only available thru dealers and a company called Baum Tools.

VAP

Mine has neither of those and works great. Whats up with that? I'm all eyes/ears, believe me. I can't even begin to understand how or why it works so well.

Audiboy

are displayed? I only have the software cable from RossTech, but I don't have his software - actually just the free beta. I've been using the VW Audi OBD software tool - never paid attention to the version. I also have a generic OBD Tool from Baum which I used for all OBD IIcars including my Audi sometimes. One thing I noticed is that sometimes the generic will not show all the errors, but the VW Audi (VAG) tool will (such things like secondary air injection on 30V's etc)

Maybe you should try the RossTech for kicks to see what it finds on that light

VAP

I also have a Pro Diag thats very new and in a Sony hand-held. And like I said the 1551 is a VW/Audi Group part with a VAG part number. There are no codes, faults, strange or out of parameter readings in any of them. On the contrary, they are all nigh on perfect, optimal readings. The car is inexplicably fine, great in fact. But I'm still waiting on the other shoe to drop... any second.

And after stopping, pulling codes the first time the CEL hasn't re-occured. I'm stuck for any answers.

MikTip

<center><img src="http://pictureposter.audiworld.com/6607/maf1.jpg"></center><p>This is the older style Hot wire sensor, earlier Audi's came equipped with. Which run better with a recalibrated MAF.