[T3] Temp sensor and MPS problems on new motor

[Keith Park]

This kinda goes along with my findings on my own car and the gas situation
here in NY,  Jim makes a good point that you really need to make sure
everything is working and set properly before trying to tune the FI but it
looks like you have done that and covered your bases.

Please define "bad gas mileage" though, and what conditions your seeing it
at, highway and what speed?  I think Jim remembers the good ol days of
leaded gas and 28mpg on the highway and I remember them too, but with
ethanol and the additives today they are LONG gone! at least here in NY. The
early cars do run leaner, but they ran TOO lean and thats why VW richened
them up so folks
wouldnt burn valves and pistons as often, for me in stock form, 25-26MPG on
the highway at 70 is about what to expect, higher if your going slower lower
if your pushing a head wind, you want to err a little on the rich side
rather than the lean side.

unplugging the air temp sensor drove you richer about 10%, but adjusting 
the MPS is the right way to do that and retain the warmup curve you want.
IF your running smooth and the AFR numbers are 13-14 on the highway thats
what you want, your done.  If something is wrong at this point mixture wise
you'll see it in gas mileage anyway, at least on the highway..  In the
winter in NY you may only get 17-18MPG in town.  AFR at idle is relatively
meaningless.

Ill say it again, IN NYS you WILL NOT RUN Properly on today's gas without
richening it up!  The ethanol is only part of the problem.  IF anyone on the
list is running untouched FI or stock jetted carbs on NYS gas and has no
issues please chime in, non of my open-loop cars do!

ya should have driven the crate when it first saw the road again with stock
jetting, horrible lean-miss on acceleration and 35MPG was WAY too much!  I
think I went up 2 jet sizes on that and increased the accelerator pump
stroke too..

Keith


Topnotch Restorations
topnotch at nycap.rr.com
http://www.a383ina68.addr.com/radiorest/main.htm
71 Squareback  "Hothe"
65 Notchback  "El Baja Rojo"
93 RX7  "Redstur"
87 Golf  "Winterat"
 
-----Original Message-----
From: type3-vwtype3.org [mailto:type3-vwtype3.org-bounces at lists.vwtype3.org]
On Behalf Of Jessica Chase
Sent: Saturday, February 20, 2016 10:24 PM
To: type3-vwtype3.org at lists.vwtype3.org
Subject: [T3] Temp sensor and MPS problems on new motor

I think I might have been a little unclear. We have bucking when the AFR
goes lean but when we drove home yesterday with bad gas mileage and rich
AFR's (and TS1 unplugged) there was no bucking at all. The driving was
smooth but the gas mileage was really bad. Plug TS1 back in and we're lean
and bucking all over again.

Today, we tested our fuel pressure and went for a drive with the gauge
installed. The pressure was at a steady 28 psi under all conditions. We also
tested both temp sensors under a variety of temps and conditions and they
both spec out fine. We also ran tests using 3 ECU's and 3 different pressure
sensors so 9 tests all told pairing each sensor with each ECU: two B units
(neither of which ground our fuel pump) and one A unit. Each pressure sensor
with each ECU did the same thing: idled lean and then leaned out so much
under load that we bucked and could barely accelerate. The fried unit has
been out of commission since late November and it's sitting in a box waiting
to be sent to WI for a post mortem as soon as we get our lazy butts to the
post office. 

Finally, we ran a 10th test. We re-calibrated the pressure sensor we took
the epoxy out of the other day. We were so fraught being 300 miles from home
and needing to get back that we didn't reset the screw to it's correct
depth. Anyway, it also idled lean but we were able to adjust it about a half
turn counter-clockwise to get it to idle at 13.2. We took it on a 15 mile
drive and the AFR #'s were sane and there was no bucking or hesitation.
We'll do some more extensive driving and testing tomorrow. The sensor is
well marked as to the original position though the adjusting screw on all of
our sensors (both with and without epoxy) seem to be at the exact same
position..on a diagonal like so   /   with the upper part at 1 o'clock and
the lower at 7 o'clock. 

We do have one of Joe's harnesses and the injector grounds are at the center
of the case. We also tightened up the injector connectors before we
installed the new motor. We've had issues in the past with the connectors
getting loose so we periodically retighten them as a precaution. We did the
same to the injector grounds. 

Jim..we want to get a B brain from you because at the very least we want to
be safe and be able to ground our fuel pump and we're happy to re-try
everything with a known good B unit, but out of curiosity, why don't you
favor adjusting the pressure sensor?

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