RETed

I would recommend doing the rewire.&nbsp I've seen fuel pump voltages drop down under 9.0VDC!

I would seriously question that Ford Ranger fuel pump.&nbsp The stock FC turbo fuel pump is already at 53gph, which surpasses a LOT of stock fuel pumps out there.&nbsp The Walbro 255lph fuel pump can be had for about $100 if you shop around - this is "cheap" insurance!



-Ted

RETed

Depending on load, if you trigger closed loop, the ECU corrects fuel delivery via the O2 sensor, period.&nbsp It has nothing to do with the boost sensor (on a turbo FC).

Wrong.&nbsp If you're talking above 4kRPM, the TPS will usually be pegged at WOT setting by then.&nbsp TPS is basically used for closed-loop, low load conditions.&nbsp You need to remember this TPS isn't linear from idle to WOT...




-Ted

RETed

It's not necessary.&nbsp Trying to simulate varying coolant temp conditions is moot, because we're trying to simulate 90% of the driving conditions - this implies fully warmed engine/coolant with very stable temperatures.

The water thermo sensor is a blanket correction factor that adjusts across the board.




-Ted

RETed

I would recommend a Walbro 255lph fuel pump and a fuel pump rewire.&nbsp If you can't afford the fuel pump, do the rewire at least!



-Ted

vosko

iTrader: (4)

hmm. i should probably rewire my fuel pump

NjFC3S

Hey Ted, do you have the instructions or links on how to rewire the fuel pump?? I want one /w colored pictures,k?

NjFC3S

Henrik

Hmm, interesting. So your saying that fuel is grossly controlled by the AFM through all rpm ranges then. Something tells me there's more to it than that as the AFM doesn't have much range. With ~2.8V at idle dropping to near 0V at WOT and ~6k (I've measured this) that's not much span for such an important input, particularly since its not linear with airflow (it takes very little throttle to drop it down to 1V).

Henrik
87TII

RETed

Yep, it sure looks like the main sensor the dictates "load" is the AFM.

I think we went through this exercise on characteristics of the AFM deflection versus output signal.&nbsp The first 1/4 of travel is very easy due to the flapper door being perpendicular to the airflow vector.&nbsp As the flapper door opens, it takes much more airflow to slam the flapper door the last 1/4 of travel - partially due to the deflection being nearly the same direction as the airflow vector, and partially working against the expanding(?) spring...&nbsp Think about it.




-Ted

ReZ311

iTrader: (4)

^^^ What he said, but put at least 720 CC secondaries in there. Then you should be kool =)

JohnL

Just a note: I now have a 88 Turbo II with a blown motor, won't start. Mods: upgraded fuel pump, FMIC, upgraded turbo with TO4B compressor, intake, full racing beat exhaust, FCD, S-AFC, AVC-R. Car ran great, boosting to 13-14 psi. However, I was on the freeway messing with the boost controler and got a boost spike to 15-16PSI, motor shuddered a little, and thats it.. it lost power, then when I finally got home, just as I was pulling in, it died.. now won't start. I would say 10 psi is fine with a fcd. 10-12 is ok with a upgraded fuel pump and S-AFC. 13psi is pushing it with a FMIC. anything above 13 psi and its a gamble. I'm going with another mazda rebuilt motor and going to keep boost in the 10-12 range with my mods... no higher. I like to drive my car, not look at it in my driveway right now with a blown motor.

Blake_AE

Thanks Ted. I'm all over that like a cheap suit. Turbo Timer and S-AFC are on their way (:-) ), fuel pump and rewire will come with tax returns... then the dp, h-f cat, and i'll be happy for another season.

Blake_AE

There's a **** load of technical info here about FCD's and what not so I'm rating it a 4/5.

Six Rotors

iTrader: (17)

OK I will try again:
1.Basic fuel injection amount is determined by the intake air amount(from airflow meter signal) and the engine speed(ignition pulse).
2.Fuel injection timing and number of injections is determined from ignition pulse.
3.Air/Fuel ratio corrections are made adding to or reducing the basic amount of fuel injection based on various sensor inputs as follows(note NO CLOSED LOOP operation can occur when fuel amount is increased or decreased by these corrections or when coolant temp is 50C or lower):
a.Intake air temperature(airflow meter)varies from +7.5% at -20C to 0 at 20C.Note default condition for failed sensor is 20C.
b.WaterThermoSensor amount varies from +60% at -20C to 0 at 80C.All temperatures above 80C have no correction in the basic amount.Note default conditon for failed sensor is 80C.
c.high altitude correction from atmospheric pressure sensor 0 for pressures above 730mmHg to -10% at 625mmHg.
c.starting injection increase +94% to 0 after 50secs at 20C,+10% to 0 at 80C.

4.Other Air/fuel ratio corrections are made AFTER engine warm up(coolant temp above 50C):
a.idling increase-by variable resistor
b.deceleration fuel cut-by TPS and ignition pulse
c.heavy load increase-by pressure sensor and ignition pulse.
d.Various speed increase-by TPS and ignition pulse.
e.Closed loop operation-O2 sensor Mazda fuel injected cars use similar fuel control strategies,from 84/85 GSL-SE up to the Twin Turbo and none rotary cars of the same years,in many case the same sensors are used.

The point is I believe the "test",where you conclude that pressure sensor output has no part in fuel adjustment,is flawed.For example if you had an engine coolant signal less than 50C,then you could not see a fuel addition for pressure full stop.
Pressure sensor signal adjusts fuel addition in 84/85RX-7s,89/91 RX7 and 93-2002RX7 and I am sure it does in 87/88 TIIs.There is a nice short table explaining this stuff in the 93/95 Twin Turbo manual,an input/output device relationship chart in 90-91 manual.

Six Rotors

iTrader: (17)

OK I will try again:
1.Basic fuel injection amount is determined by the intake air amount(from airflow meter signal) and the engine speed(ignition pulse).
2.Fuel injection timing and number of injections is determined from ignition pulse.
3.Air/Fuel ratio corrections are made adding to or reducing the basic amount of fuel injection based on various sensor inputs as follows(note NO CLOSED LOOP operation can occur when fuel amount is increased or decreased by these corrections or when coolant temp is 50C or lower):
a.Intake air temperature(airflow meter)varies from +7.5% at -20C to 0 at 20C.Note default condition for failed sensor is 20C.
b.WaterThermoSensor amount varies from +60% at -20C to 0 at 80C.All temperatures above 80C have no correction in the basic amount.Note default conditon for failed sensor is 80C.
c.high altitude correction from atmospheric pressure sensor 0 for pressures above 730mmHg to -10% at 625mmHg.
c.starting injection increase +94% to 0 after 50secs at 20C,+10% to 0 at 80C.

4.Other Air/fuel ratio corrections are made AFTER engine warm up(coolant temp above 50C):
a.idling increase-by variable resistor
b.deceleration fuel cut-by TPS and ignition pulse
c.heavy load increase-by pressure sensor and ignition pulse.
d.Various speed increase-by TPS and ignition pulse.
e.Closed loop operation-O2 sensor Mazda fuel injected cars use similar fuel control strategies,from 84/85 GSL-SE up to the Twin Turbo and none rotary cars of the same years,in many case the same sensors are used.

The point is I believe the "test",where you conclude that pressure sensor output has no part in fuel adjustment,is flawed.For example if you had an engine coolant signal less than 50C,then you could not see a fuel addition for pressure full stop.
Pressure sensor signal adjusts fuel addition in 84/85RX-7s,89/91 RX7 and 93-2002RX7 and I am sure it does in 87/88 TIIs.There is a nice short table explaining this stuff in the 93/95 Twin Turbo manual,an input/output device relationship chart in 90-91 manual.
Anyway no more from me on this topic.

RETed

And this is from what reference?&nbsp I find the general statements hard to swallow as there is a number of changes between models - this implies control algorithms are not the same.

FC air temp is VAST different range than FD air temp - off by a factor of 100-200 times.
FC (main) TPS is very limited versus FD TPS, which is full range.
Obviously, MAP-based FD ECU control versus AFM-based FC ECU control...

You ever seen a 323GT/GTX ECU system?&nbsp It uses a BOOST SWITCH, so it has no idea how MUCH boost it's running.&nbsp The 323GTX popped up in 1988, so it's very similar timing to the FC turbo.&nbsp I find it hard to believe that Mazda went with a much more complex control system across it's different models.

I'm looking forward to the oscope tests that No7Yet is planning to do...



-Ted

kabooski

Well as more I think about it
It could be a bad fuel filter
or weak fuel pump that was leaning me out

I think I cracked a corner seal
But no biggie
Now I can do a little more porting

Henrik

RETed, I understand that the relationship between airflow and flapper position is not linear. All I'm saying is if that's the major input at all RPM's I find it strange that the signal has such a narrow range, basically less than 3v. 40% of the range of the sensor is lost to 'below idle' rpm's. Maybe the fueling is not that accurate?

Six Rotors: Where did you get your info from? I've seen the input/output map in the 89+ FSM, but I've never seen ranges of affect anywhere.

Henrik
87TII

MaxRX7