rickou

hi !

i'm new french owner of 1990 RX7 Turbo II.

i need help to start it !

for now, i need to know what is the normal duty cycle for BAC solenoide and boost pressure controler solenoide when ignition is ON (engine not running)

my car model is JMZFC1332.

can anyone help me?

thanks a lot !

Malefoda

Use the FSM

RB_eater

iTrader: (1)

Solenoid, there's no e in english.

well uhhh

no E huh? I had to read this a few times. I know there was a comma, but still confusing. I LOVE ENGLISH.

NJGreenBudd

iTrader: (1)

Index of /main/factory_service_manual/1989_1991


Section 04B, page F2-39 for the BAC specs

Section 04B, page F2-41 for Turbo boost pressure control


Welcome to the Club, post some pics of your TII!!

HAILERS

I could look at the BAC duty cycle with the key to just ON (Fluke digital meter), if you still need that. BUT let it be known, the BAC goes full open and stays full open during START. LIke if you took the bac off the engine but left the electrical connector on the bac, then went to START with the key, the bac's diaphram would go and stay full open.

I've a series four so I have no Turbo duty solenoid.

During START the ECU uses : rpm under 500, water thermosensor resistance and the START signal from the ignition switch. Afm is NOT used. See this chart. https://www.rx7club.com/attachment.p...3&d=1200400936

IF you suspect the engine is flooded, then on a series five car, if you hold the pedal all the way down, that cuts the fuel injectors off while the engine is being turned over by the starter. The ECU looks at a full TPS signal (pedal to the floor) and the START signal from the ignition switch, to cut the fuel. Let off the pedal and the ECU spits fuel according to the CHART I attached above. More fuel the cooler the engine is. Less fuel the hotter the engine is.

ramses666

iTrader: (1)

UH..... What is the problem? No start? Probably flooded. More details needed.

Ramses666

rickou

hi there !

thank for your help,

first, i'm french guy, and my english is not so good, then excuse me for the lacks, i do my best !

i need to know the duty cycle only to check if my ecu/harness work fine for theses two solenoids. i'm on another french forum (www.rx7france.com) that say me the boost solenoid should not clicking, mine click ! BAC solenoid too. then i want to check if frequency and duty are good. i work in electronics then i doubt the frequency is too low. but i haven't found anything about that. HAILERS, if you can help me for the BAC frequency and duty when ON and COLD..

so the main problem, is the car don't start and flood very very fast. i already check the injectors (no leaks, open and close good, but i haven't tested the flow), when cranking, injector active state take 50 milliseconds, (i mean it's too longer, but i don't know the correct values), i have check fuel pump, fuel pressure (betwen 2 bars and 2.5 bars, seem to be good), battery is ok, starter too, sparks plug and coils good too (check spark fires, check coils commands from ecu), i have check the crank angle sensor too (signals at ECU are good)

so, sometimes, the motor start very quickly, last week end, i change the spark plug, then start and it run good to 3000rpm very very fast ! but when the rpm fall to 1500 it stall. after this, impossible to start again. some hours later, i can re-start again, then i play with the gas pedal ! all seem to be good, but i don't know why, i have stopped the motor after some minutes. Then again, can't restart. (i know this is the best way to flood the motor but i don't remind why i do this )
after each try, i unplugg the sparks,witch was full of gasoline each time, then i make starter run without EGI fuse to empty the rotors, dry the sparks and plug it again.


so, i check the compression too (with standard tool) , front rotor say 6 bars, and rear rotor 3 bars. (it seem's the rear rotor is dead..but with this poor tool...i don't know exactly)

this motor has to be changed last year be previous owner, but he never has succeeded start, then when i buy the car, i have found lot of vaccum lines not plugged, then before rebuild the motor, i want to check if all is good around.
i only want to make the motor to start quite fine, even if it can't be used on road.

do you think that I dream to start it with compressions as bad?

I precise that my car seems to be a "special version" because I have'nt found any FSM or other docs for it. (ex: my fuel pressure regulator have 2 vaccum lines, and so 2 solenoids and one other black box and check valve ! all this only for fuel pressure regulator ! but there is others differences all around the motor)

Now, place to the pictures of my TII :

(it was cold this day ! )

HAILERS

Read this article: http://www.teamfc3s.org/info/articles/idle.html

It's an article about turbo problems but the BAC works the same.

I just read this post. I've been playing today and forgot this thread. I'll get on it in the next hour or so and if not......after lunch tomorrow.

It's good that your clicks/has a duty cycle. But remember this. On START it goes and stays full open as long as the key is to START.

Just something to think about. Check the output of the water thermo sensor and compare it with the FSM (Fuel and emissions section, Control Unit). IF the water was hot then output will be a half volt give or take a little. Like 4.5vdc if over 180*F and a figure of 0.5vdc is normal also.

As you could see in the Chart, the temp of the water plays a big part in Starting the engine. IF the water thermosensor is disconnected, the amount of fuel delivered during Start will be too little. That said, I'm not sure that is your problem, but check the output of the water thermosensor. At least make sure it's connected up.

Off to find my meter and a Cold engine. Later.

HAILERS

I can't find a cold engine. I found my 86 has a engine temp of 90*F. I put the meter on vdc, first, and on the BAC's pin of the ECU. Key to ON. The voltage was at first 9.5vdc but after about 8-9 seconds it dropped to 1.44 vdc. Meaning it went full open and stayed there.

I started the engine at 90*F and the freq of the BAC was 122hz after starting. The duty cycle started out at 3.4ms and steadily dropped to something like 2.6 ms. Aw shucks. I forget. I think it started out at 40% duty cycle. Forgot to write it down.

As you know, the bac's duty cycle is influenced by several things. Like the condition of the battery and if headlights are on. Loads is what I mean.

Anyway, the engine temp got up to 140*F and I stopped. I noticed that NOW if I just put the key to ON, the voltage is in the 9.5vdc range and stays there. It does not drop to 1.44vdc as described above. So engine temp seems to decide *something* as to if it stays full open or does its duty cycle on/off etc.

So. The first part of tomorrow I plan to row my boat. Maybe in the second half of the day I'll get on the car with the cold engine and start over again.

By the way, I can look at the duty cycle of the fuel injectors when I try to start cold tomorrow.

European cars are different and in what respects I don't fully know.

By the way, in the past I've seen the bac on my cars vibrating away when the key was put to just ON and not running. So that's not unusual. As to what the engine temps were in those cases I don't know. No matter. DURING start, the thing should go full open and stay there until the engine starts.

Your English is fine. We can comprehend every thing your writing.

ramses666

iTrader: (1)

Uh... the engine is flooding... maybe put a switch on the fuel pump relay & discharge all fuel pressure before turning engine off - therefore no flooding possible - standard band-aid for rx-7.

Ramses666

HAILERS

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>


.......if it's a series five engine/car, all one has to do to stop a FLOOD, is hold the pedal to the floor. That act kills the fuel from the injectors. The spark is still there and the turning of the engine over will kick the excess fuel out the exhaust. The residual fuel then catches fire and the engine starts. Operator lets off the pedal when the engine fires and fuel is then injected again to keep it running.

Anyway, the thread owner asked about duty cycles. I think he asked about duty cycles because the thing won't idle once started.
I think it's more than the BAC's duty cycle (he says it works) that is keeping the engine from idling once started.

So we agree that the duty cycles of the BAC and Turbo duty solenoid are not the real problem. But if one asks about the duty cycle, I can give the duty cycle during and prior to Starting. At least for the BAC.

If the engine starts and won't hold an idle once fully warmed up, the BAC is a thing to look at, but since it is working, then something other is wrong. Jumpering the Initial Set Coupler puts the BAC in a set Duty cycle. You jumper that connector when tuning a engine for that very reason. You don't want the BAC to be carrying the idle load all by itself. Then you make sure the timing is right and adjust the BAC air screw to set the idle speed. If it won't idle right then you look for the usual air leaks around the turbo inlet duct and various other places until you solve the problem.

Anyway, the thread owner asked about the duty cycle on a cold engine and I'll give him that.........later when the sun rises and I get though rowing. It's 2:59 am.

Malefoda

What's strange for his engine is that there's many "non standard" stuff, as no afr adjustable resistor for mixture idle or such. This makes the FSM a bit out of purpose.
I think there's a lot to learn from this case

HAILERS

I tried a cold engine. Water temp 77*F.

Bac duty cycle 100* and it's voltage showed it. It was at 1.44 vdc all the time. The BAC was full open and the ignition switch not even to start.

Started the engine up, and fully hot, the BAC's duty cycle is about 54%. Depending on electrical loads on the engine and other Loads that figure can change. Like turning the lights on or the a/c on will up the duty cycle. On the whole the thing has a freq of 122 hz.

As far as fuel injection During a start, with water temp 77*F, the injectors were open 44 ms. With the water temp at 120*F it was 29ms and 150*F it was 21ms and at full temp of 180* F it was 14ms. I'm talking the open time of the fuel injectors DURING Start, not after. I disabled the fuel pump when looking at the injector duty cycle doing the above.....so the engine wouldn't actually start.

IF you remove that START signal wire from the ECU, then at 180*F the fuel injectors would use the afm to determine fuel and you'd see the injectors open something like 6ms instead of 14ms. Quite a difference and the 6ms won't cause a Flood when the engine is HOT.

The RTEK2.1 has a feature where you can adjust the amount of time the fuel injectors are open during START. It's having the ability to adjust the ECU to fit the condition of the engine.

The LINK I attached in a post above dealing with TURBO II IDLE PROBLEMS should help out a bit more than knowing the BAC duty cycle. BAC is full open all the time during START. 100% open.

rickou

hi Hailers !

very big thank for yours measures ! now i can check if my car's BAC work like this !

i mean my car series is Five, because when i push gas pedal to floor, injector stop to open.

big big thank again ! i come back this week-end after i check how it work for me.

rickou

hi there !

i have made some test this week end on my RX-7.

i found 121Hz for frequency, but for BAC duty i get some strange things.
only ignition ON (engine not runing) the duty vary from 20% to 60% without doing anything ! (i have done this test with BAC connector unpluged !)
when i cranck, then i get a near 100% (always with unpluged connector, i get some very small 12V pulse then duty near to 100%)

i have bought new ignition leads and a new air filter too. i'll test the new ignition leads this thursday.

i have re-check the compression for 2 rotors, then i get 6-7bars for front rotot and 6bars for rear rotor. (last time i check it, i don't know what i do to get poor results..)