Dyno-Less tuning?
peter paul fenske
ffnsp955 at bcit.bc.ca
Tue May 19 06:51:11 GMT 1998
Awesome Thor
At 01:49 AM 5/19/98 -0400, you wrote:
>
>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)?
>
>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:
Prob not. Enough to get it running though
> 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 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.
O2 tuning is usually done with a oscillating control
loop treating the O2 input as a step. There is also
quite a delay time..
Do as GM did and tune your system for stoich with the O2
not running. Only when you get it tuned play with the O2
> 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).
Transient in the simple is just delta throttle say measured at
each 6.25 mS RTI and coolant temp based on a 2 dimensional
table. This looks up a small addition to your PW
Oems use more. absolute Map, Tps, then the delta terms along with
coolant.
> 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!).
>
> 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 rpm
>starts 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!]
>
> 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?
I hope you are filtering you map. A simple first order digital
filter is easy to implement. Do it at each 2nd RTI or so
also pull vac from a combined fitting to get more consistent
map.
> 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...
>
>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
Pretty good so far..
:peter
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