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8
Oct 05
Engine Computer
I wanted to
stay with EFI, but it was recommend that I replace the 1995
"W4H0"computer
with an earlier "A9L" unit. The 94/95 computer does some
strange things with the timing, such as backing it out during
a shift, it also calculates the air/fuel ratio a little
different. Its basically a performance dog!
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Stay tuned, this ought to be
a fun area of the site, I'll post the tunes, dyno runs and
any thing else of interest.
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| 16 Oct 05
Engine Computer Parts |
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To keep the
older A9L computer happy, several components have to be
changed to 89-93, here's the list so far...
- Computer
- EFI injector wire harness
- Computer wire harness
- Throttle body and associated
sensors
- Distributor
- Connections to main
car harness
- Oxygen Sensors (4 wire
vice 3)
- ACT, early years mount
in the intake, later years in the air intake.
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NOTE: The marking
stripes on the wires are painted on so be careful
with what you use to clean them.
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mess left above is both the 1995 and part of a 1990
computer and EFI harness I got from eBay. The '90
harness will have to be "adapted" to fit the 1995
main car harness. I suppose I could modify the '95
EFI harness to work, but decided to keep it and
the W4H0 computer as a back up in case something
went wrong. In fact, I plan on getting the car running
using the newer W4H0 computer, then changing it
out. The picture on the right shows all of the harnesses
laid out while we tried to identify the various
parts. |
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| 5 Nov 05
-- New Plan Going
with the Its A Snap harness and
the '90 EFI harness.
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W4H0 computer is history!
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12 Mar 06 -- New ECC |
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| Here is the
new remanufactured ECC, its Cardone part number 784352 ,
$96 and a $45 core charge. I also bought a GP Sorensen Idle
Air Control Motor, # 77910023 $55 and two Bosh 3-wire Oxygen
Sensors #13953, $42 each. All from Advance Auto.
Top
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The Cardone ECC's have a 90
day warranty, while the Standard has a one year warranty,
but costs almost 50 percent more.
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| ID your
injectors
Injector Colors
14 - gray
19 - yellowish-orange
24 - light blue
30 - red
36 - brown or dark blue
42 - lime green.
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ID your EFI harness!
It turns out that the 1990 EFI
harness is an odd ball. It does not match the other year
harnesses, nor does it match the new 94/95 harnesses.
It drove me nuts trying to trace wires in it, it matched
no references I had!
"Does it have a brown 8-pin plug and a
green 8-pin plug at the opposite end? If so, it's a 91,92
or 93 EFI harness. If it has a grey and a black 8-pin plug
next to each other and a green plug at the opposite end,
then it's an 89 harness. If there is another grey 8-pin
plug next to the green plug in addition to the 89 plugs
shown above, it's a 90 harness." from
someone on an internet forum
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| 6 May 06
-- ECC Update |
| Some of the
wire color codes in the 1990 harness did not match the codes
in the EVTM I got from Helm. |
I wound up tracing many
of the wires back to the 60 pin ECC connector to verify
them. Just have to assume the actual pin layout matches
the EVTM diagrams. There were also several "pass thru" wires
in the EFI harness; they did not connect to the computer,
but just routed circuits thru the harness to other parts
of the original car. |
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19 June 06
-- Tweecer ECC Initial Settings |
| Initial A9L
tune, click
here to download it. Use at your own risk.
Click here to download
the MAF transfer for a 75mm Pro-M TB calibrated for
24 lb injectors.
Cam Card for
Comp Cams XFI
Stroker Cam: XFI 236HR-14
I'm waiting on my registration
code for
EEC Analyzer (EA)before I adjust any more values
Top
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Note these steps and the
other info on this site is not meant to be a step by step
guide, but rather suggestions at things to look at and things
I have done. This A9L
tune removes the smog equipment, sets the injector slopes,
MAF Transfer (my setup is 30 lb injectors with a 75MM Pro-M
calibrated for 24 lb injectors) Injector breakpoint and
Injector Offset vs. Battery Voltage ( I multiplied the stock
values by 19/30 (.6333) to get these new values, where 19
is the stock injectors and 30 is the new ones) Engine displacement,
Checksum base address = 0, sets the idle RPM and removes
the speed limiters, and sets the Min and Max MAF Voltages.
Tip: Before
starting the tuning process, ensure the engine mechanicals
are 100% -- No vacuum leaks, set TPS voltage, etc.
Tip: Set
a scalar value, then click Refresh on the Tweecer CalEdit
Screen, it will adjust the values you enter to fit into
the ECC's memory space.
Tip: Do NOT
check the Update Only box, it will corrupt the tune. (bug
in v1.30A10, may be fixed in later version of CalEdit???)
Tip: SAVE
YOUR WORK OFTEN!!!!!
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Tip: Use cardboard
or other material between the ECC and Tweecer box to keep
it from twisting and losing contact. |
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Tip: Before installing the Tweecer clean the fingers
(both sides) on the ECC connecter until they are
a little shiny with a pencil eraser.
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9 July 06
-- Another Tweecer Tune |
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This tune richens the idle 8%, it also enables the fan
controls, changes the ISC closed loop RPM correction rate,
and uses some MAF corrections from EA plus some other stuff,
use at your own risk. |
Tip: if
you are working away in CalEdit and all of a sudden, CalEdit
refuses to change scalar values, either with the up/down
control or by entering the values directly, it means the
tune has become corrupt and is suspect. Recreate it manually
from scratch (you saved the MAF transfers etc, right?) |
| Here's a way
to clear the ECC KAM so new adaptive values will take effect
sooner. Note you may want to use a momentary switch so the
switch can not be left in the "ground" position. |
Apparently the ECC KAM has another
source of power when the key is on, so the switch may not
act as a theft deterrent. Regardless it beats waiting 30
minutes or so for new fuel and air ECC settings to take
effect, use at your own risk. Some folks
upload a wrong tune to one of the Tweecer switch settings,
then use that wrong tune to clear KAM.
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| 14 July 06
-- Another Tweecer Tune |
| This is the
best A9L 347 tune to date, the car idles fairly good
at about 900 RPM, it still bucks a little, but not as bad
as before.
Next step will be to adjust
the table Injector Timing (FN1315) via EA, I understand
it to be a one time adjustment, once set it should not need
further tweaking.
Top
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I scaled the functions Injector
Offset vs. Battery Voltage (FN367), Cranking Fuel Pulse
Width (FN348) and Fuel Table - Startup (FN1306) by .63333,
which is 19/30 (19 old injectors, 30 new injectors) The
Injector Breakpoint (FN389) was set to 1.05 based on earlier
EA analysis. I had
some trouble with the ISC functions in EA, so I just set
the scalar Throttle Body Airflow (ITHBMA) to .649902 by
trial and error. I noticed that if this value is too large
the car will run rich at start up and even flood.
EA recommended 30.55
and 39.589 for the injector slopes, so I used those values.
I also used EA to tweak
and fit my original MAF curve. Some individuals suggest
that the upper voltage should be 16, not 5. In that way
the computer will continue to use the curve, but the scalar
MAF Voltage Maximum (VMAMAX) contradicts that theory, since
VMAMAX is supposedly the max value the computer will use
in the airflow calculations. However, do set VMAMAX as close
as possible to 5 without going over 5 in CalEdit.
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| 4 Sep 06
Computer Problems?? |
| Been chasing
some issues with the tune and computer. The car started
running badly, so we've been replacing one component at
a time in an effort to find out what broke. |
| This is the
remanufactured ECC, if you look closely, you can see where
its been repaired. I suspect it went bad again, but there
is really no way to test it. I have to get another ECC and
put it in the car. |
 
Turned out that there is nothing wrong with
the computer.
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