MAP sensor vent

Phil Lamovie injec at
Sun Aug 8 18:41:23 GMT 1999

Hi All,

John wrote;

> MAP sensor vent for the Honda engine is located about 5 mm
behind the
> throttle plate.  Once the throttle is opened wide my MAP goes
> atmospheric.

Sounds like you found a convenient place to stick a vacuum hose
but given the shading of the port at part throttle very unlikely
to be
a "true" reflection of load. Try moving the hose to the plenum.

All throttle excursions need to be treated with respect.
More than X translation in an increasing load direction should
cause the
ecu to default from closed loop to open. At this point the
fueling should be 95% correct as it was established by steady
state testing and calibrating.

It seems that your system may be "hanging on" to the closed loop
algorithm a little too long. Instead of a base operating
condition of closed loop try setting the base fueling to the max
power table and then apply time/throttle deg/rate of change of
rpm conditions before electing closed

Just as you worried about the TECHONOGICAL miracle of valve
vs injection timing you are trying too hard to keep closed loop
as the basis of engine fueling.  Plain old dumb mapping is very

8 bit rpm X 8 bit load = 65,000 carby  jets

By this I'm refering to a 4 point map with interpolation using an
8 bit A/D converter.

There must be a value for every load / rpm possible not just WOT.

The accel enrichment is used to mask the lean out caused by
system lag
(your code plays a part here) If you can successfully calculate a
new open loop injection value every rpm then accel enrichment is
used for less than 0.5 of a second, any longer and it's just more

re bailing wire see page 194

"Stainless-steel spring wire DIN no. 17 224

Alloying constituents in % by weight
<0.12 C; 17 Cr; 7.5 Ni; E=185,000   G=73,000
For 1mm diam N/mm2 min. = 2000
Z=reduction of area at fracture 40 %
Permissable bending stress =1400 N/mm
Permissable lift stress cycles endured =380 x 10 to the 7th
etc etc etc  add 40% for shot peening (see page 286/287)

I kid you not !


 Phil Lamovie

 injec at

     cogito ergo zoom

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