Let's get some in depth discussion on how all this stuff relates...I got a couple issues with DIY ITB settup and having a little trouble getting things straight.
I am running a Power FC and tuning myself but can't seem to get any good advise on tuning with it from others that are knowledgable on here.(I KNOW THERE ARE SOME)

-What do TPS sensors tell the ECU?
-What do MAP sensors tell the ECU?
-What range should vacuum be at normal idle with ITB's?
-What inputs(sensor readings) determine fuel addition?

**Lets share the knowledge here people and not just use this board as a gossip corner.....

 

well, i have DIY ITB's i made running perfectly on my dohc zc.....besides the fact i blew a headgasket a few weeks ago (replacing tommorrow). i daily drove them for abour 1500/1600 miles........and i was getting 34 MPG highway. basically, i bought a vaccuum gauge, saw where i was at vaccum, and made a fuel map (ghettodyne) that was between 16 inhg vac. and 0 inhg vac, instead of 26 and 0. i adjusted the ignition maps also, but not as much. the car is completely driveable. i suspect the TPS does more than i thought it did. it seems the ECU is pulling fuel from low TPS readings, as on the highway i'm only really at around 5 in vac, and theoretically at that vac and RPM , i should be dumping tons of fuel, but i'm running lean almost, floor it and she pours it on. ITB's have been a very fun project for me overall, i'm happy i did them. mainly it was to see if i could, everybody in town thought it was nuts, now i'm daily driving them perfectly. we datalogged w/ ecucontrol to see where all the readings lie.....and everything is differnt. fuel is the biggest problem though. TPS controls a LOT though, at least w/ obd0 i suspect.

 

I was always under the impression the TPS simply was a reference point on wiether the ecu should be in open or closed loop.

At part throttle/cruising, the ecu takes readings from the O2 and adjusts fuel based on that.

Once you go WOT (or what ever percentage of throttle you need to throw it into closed loop) the ecu reverts back to the WOT maps?

 

good thread.......ttt

 

The following links will provide a breif description of the three ECU inputs :
O2- Lambda Sensor (Zirconia) Waveform Notes
TPS- Throttle Potentiometer Waveform Notes
MAP-MAP Sensor (Analog) Waveform Notes

In some cases the IAT(intake air temp) or ECT(engine coolant temp) can be used as an input for fuel correction. This is usually done in "Open Loop", and would be used to adjust fuel/idle because at this time the ECU would not be monitoring the O2 sensor.

- What range should vacuum be at normal idle with ITB's ?
Unfortunately i do not have first hand experience with this. Although what i suggest to be the first coarse of action would be taking a vacuum reading as close as possible to the map sensor on a manifold system, then again another reading on your ITB system. Compare readings and go from there. if your seeing a loss in power it could very well be that the MAP sensor is causing the ECU to not see proper voltages there for dumping more or removing fuel.