Dyno-Less tuning?

[Raymond C Drouillard]

On Tue, 19 May 1998 01:49:52 -0400 "Thor Johnson" <thormj at earthlink.net>
writes:
>
>Brief recap... this is a 68hc11 EFI (fuel only) for a Honda
>CBR600 motor.  All homemade stuff.
>Calculates base PW based on MAP, all other sensors totally
>ignored (incl RPM)... batch fired at #1 intake stroke.  How
>important is RPM (considering I'm injecting 1/rev anyway)?

It wouldn't be important at all if your volumetric efficiency remained
constant at all speeds.  Of course, we know that this isn't the case. 
The amount of fuel injected needs to be reduced in the areas that have a
low volumetric effieiency.  Generally, this means the low speeds where
the cam overlap reduces volumetric effieiency, and the high speeds where
there simply isn't enough time to gulp a cylinder full of air.

>
>Ok... now that I've gotten my ECM to ignore noise on the Cam
>sensor line, I *think* I'm ready to start tuning the thing.... I
>am not having as much success as I thought I would though, so I
>have a few questions:
>
>  1. Can I effectively tune in neutral?  My data comes outta a serial
>      port & my host pc is AC-only. (Is there a way to hook a cellphone
to
>      an external 9600 baud serial port/modem?  My ECM don't do PCMCIA!
>      I can choose from PowerTel PCS or bellsouth mobility D/A phones.)

I bought a cheap used laptop to do my tuning.  It's an old 486 DX2 50
(50/25).  With the Holley, I could actually go as primative as a 286. 
How primative can you go?  Maybe you can find someone with an old 386
laptop that is gathering dust.


>
>     I am trying to tune in neutral...  It doesn't seem to reflect
>     "loaded" conditions very well.  I'm currently ramping *slowly* to
>     try to get the "static response" tuned up.

Do you have an automatic?  The torque converter makes a dandy static
load.


>
>  2. What should be my goal?  Should I attempt to maintain a consistent
>      O2 sensor voltage across the RPM range?
>
>     I'm trying to keep the incr in throttle from making the oxy go lean
>     and the engine sputter & die (this is accompanied by a steady rev
of
>     the engine at the constant throttle posn).
>
>  3. How do I handle transient effects?  I am toying with the idea of an
>     "electronic accelerator pump" that has "addtl fuel" vs. "delta
throttle".
>     Should I make the length of the effect (decay curve?) adjustable or
will
>     a "single shot of gas" do it?
>
>     Right now my maps look like a small slope in the 0-10PSIA, and
about 10x
>     that in the 10PSIA+ entries.  This gives ok starting from idle, but
>     flooring it while 6-8K will still cause it to stumble(badly!).

I don't know what you are using as an ECU.  In the holley, there is a
table that is used to specify extra enrichment when the throttle is
suddenly opened.

BTW, there is another table that specifies extra enrichment when the
engine is colder.

>
>  4. Do Ego's have memories?  At times, the RPM will increase before the
throttle
>     opens, the oxy goes lean & the engine quits.  The only thing I can
think of is
>     that the mixture was already lean (but the sensor was still reading
rich), so
>     the R's went up.  The oxy falls .2-.6 secs after the rpmstarts its
"death rev."
>     These are 1yr old sensors, 3" from exhaust port, running M85.  They
have been
>     sooted to death before (as have the plugs....). [PSST. CSH trick: 
To clean the
>      plugs, we lean the A/F mix by switching off the fuel pump before
shutdown!]

O2 sensors tend to slow down with age.

>
>  5. I am getting some wild variations at certain R's among the 4 Ego's.
 It only happens
>     at certain R's (& best sound is a Rich-Lean-Lean-Rich pattern
[1234])... does this
>     indicate an airflow problem in the intake system (composed of PVC,
18mm restrictor)?
>     How bad does this hurt us/the engine?
>
>  6. I'm taking MAP readings about 6" from the cylinder inlet. The
intake is 1" sch40 PVC
>     molded in an attempt to maintain an 8 degrees exit angle to the
head from the 18mm
>     restrictor (a la fluids).  Is this a bad place to do this? I tried
at the test ports
>     of the cyl intake, but the vacuum fluctuated wildly there....
>
>---
>
>I have some nice long data logs that look like (like hondo?):
>  CamDT, Throt, PSI, Tp1, Tp2, Tp3, Tp4, Ox1, Ox2, Ox3, Ox4
>
>I've loaded these into excel to assist me... does anyone have a
>"tuning your ecm with excel" faq?
>I have lots of points, but I have no idea whats going on....
>they make pretty lines...

I wrote some programs in Foxpro that I used to statistically anylize the
data and use it to tune the engine.  If you want, I can send them to you.
 You'll have to modify the code to use your data, though.

>
>Currently, I'm leaning the whole map out until the engine hardly
>runs, finding that MAP value, twiddling with it (slowly) until I
>get Ego's in the range I want (which changes the RPM!), doing the
>same to the new RPM... I can't quite get it to converge.  To get
>the upper PSI points, I have just *completely made up numbers*
>that attempt to elimanate idle->WOT stumble.
>It doesn't help 1/2throt->WOT very much.
>
>I'm also thinking about making the ECM output binary... I can't
>get anywhere near 1 row/CamR with this excel/ascii format (9600
>baud), but I'm wondering how much that extra data would help me,
>vs the trade-off in convenience/readability....
>
>As you can see, I'm confused when we try to get these things to
>work in reality instead of theory...
>
>TIA,
>Thor Johnson
>
>

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