problems with EFI car idle and pressure sensors

[Dave Williams]

-> This raises an interesting point. I've data logged at about 50Hz, and
-> on a sharp throttle opening MAP changes almost instantly, i.e. in
-> about 1/25 of a second. You can't move the throttle much faster than
-> that.
->
-> Why would I need TPS? (Except for overrun cutoff, etc)

<sorry for the extensive quote>

 MAP-only will work fine with a mildly tuned engine - the old Bosch
D-Jetronic system essentially worked that way.

 With longer intake valve durations or intake manifolds of small volume,
or both, MAP becomes very unstable at low throttle settings.  You can
spend a lot of work dampening the signal via mechanical, electrical, or
software means, or you can just stick a TPS on and give it preference at
low throttle settings.

 On supercharged vehicles, MAP is not necessarily related to engine
load.  On my turbocharged Yamaha I can see the boost go *up* temporarily
when rolling the throttle *off* at high speed.

 A TPS is also handy to detect conditions suitable for deceleration fuel
cut-off, and for a "flood clear" mode if the vehicle has trouble
starting.  Finally, TPS and RPM are sufficient to provide a limp-home
strategy in case of MAP sensor failure.  The older Holley Pro-Jection
worked that way by default.

 You don't *have* to have a TPS; but it's handy to have.

=====dave.williams at chaos.lrk.ar.us========================DoD#978======
  can you help me...help me get out of this place?...slow sedation...
ain't my style, ain't my pace...giving me a number...NINE, SEVEN, EIGHT
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