[s-cars] MAF upgrade?

[Philip Mische]

I decided to go with a stock Bosch MAF - I had that opening a can-of-worms
feeling coming on.  Yes it is a system where harmony is most important to
good performance, and I can't devote myself to another hobby inside the
hobby right now....

The hesitation / stumble / surging, posted here to the list a few times,
happened 2800-3500 rpm under light loads, like going up a hill at part
throttle.  The strange part was that the problems came on immediately after
I replaced the battery(!)  In addition the throttle was like a wet sponge.
After rounding up the usual suspects (plugs, plug connectors, 02 sensor) and
not getting it done, I took the car to Greg Haymann at Autofirme.  He
diagnosed the problem in less time than it took me to train home.  He said
mine was "way out of range".   How did he know?  Hey, if I didn't look in my
Bentley to figure out how to test it before I'm sure don't want to know
now!...ok, ok, I just looked in Bentley (J24-79, 81, 83) - looks like a VOM
is all you need....wish I'd done that.  Btw, it threw no codes.

Where and how are you measuring the pressures?

Phil

----- Original Message -----
From: "MLP" <mlped at qwest.net>
To: "'Philip Mische'" <pmische at comcast.net>; "'S-Car List'"
<s-car-list at audifans.com>
Sent: Wednesday, April 16, 2003 3:10 PM
Subject: RE: [s-cars] MAF upgrade?


Phil -

I've hesitated to say anything at all about this, but.....

Alternatives exist, but are they better?  That's very much a YMMV issue, and
IMO for all stock to RS2 applications, probably not.  Past RS2, is there a
better MAF?  I'd give that very qualified maybe, and you have to remember,
the MAF is just one component of a fairly intricately intertwined system.
Any measurements that could / would "quantify" the benefits (other than Rod
H finally reportedly perhaps finally drawing a breath deep enough to suck
the hot wires off a stock unit his through his intake manifold) have yet to
be made or taken.  At the time Rod was pretty bummed.  I told him he ought
to look at the bright side.  By my guess, I told him it could be seen as a
sign, and he could claim it as some sign of proof he'd finally passed the
400 to 450+ bhp mark :-).

In the course of chasing some of the above, there is another question /
possibility that can be asked about the origins of a MAF cause stumble.
What thoughts are there re feed back from too much pressure in the intake
track causing "blow back" via the BPV that confuses the MAF?  Any takers?

I can tell you that under highway cruise conditions, say a steady 55 - 70
mph, light throttle application with a basically stock car (i.e. K24), one
can be running and holding 5"+ of (I believe the Autometer gauge is
calibrated in Hg) vacuum in the intake manifold, but have the turbo pushing
4+ psi of boost at, in and through the intercooler up to the throttle body.

Mike BT&PD(S)T **


** (been there & painfully done (some) of that)

BTW, for those who enjoy anagrams, I see that if you carefully rearrange the
last part, SDT, you will come up with a STD



-----Original Message-----
On Behalf Of Philip Mische

Apparently the stumble I've been chasing for quite some time is a bad MAF
meter - it puts out bad values.  Yes, it's been cleaned.  Has a better
replacement been found for the stock Bosch unit (best price so far $405)?

TIA,

Phil Mische
95.5 S6, MTM/Hoppen Stage 2, RS2 EM
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