Th0m4s

As the name says I'm missing my fast idle when i'm doing a cold start. Sounds strange but it's true. It was there before the engine got new vacuum hoses but now it's gone. No 3000 rpm fast heating at all anymore. I'm not pressing the clutch nor starting with the first gear.

By the way my water temperature sensor is showing much too low temperatures.

There's also another big problem. My car is losing power when it's getting hot. I just regrounded Pin 3a and 3g and all my problems (but the missing high idle) were gone as long as the car was cold. When it got hot the car started doing strange things and losing power. It was like the Turbo was only running with half the normal pressure. I'm really clueless why it's only happening when the engine is hot.

By the way what exactly are pin 2c and 2r for? I know they are grounds but what are they for? They look different from 3a and 3g. 2r was connected to wire 3a so i regrounded that one, too but i didn't do anything with 2c because it looked like it wasn't connected to any of the other ground wires i regrounded.

satch

iTrader: (1)

The 3000 rpm warm up does not occur when the coolant temp is below a certain threshold which is around 60 degrees. This is done to prevent a cold block from being reved and possibly damaging it. There is a temp switch at the bottom of the radiator which checks the coolant temp when a cold engine is started just for this purpose.

Pin 2R is a repetitive ground as it ties into 3A. 2C also ties into 3A. There are two crimps between 3A and 2C. If these crimps are bad then 2C loses its ground and 2C grounds out the engine sensors. It's best to ground at all four pins to reduce any possible grounding problems.

Pin 2I is for the Water Thermosensor located at the back of the water pump. It measures the coolant and sends this info to the ECU and helps the ECU to decide how much fuel is needed to start the car in addition to how much is needed to run the car at various engine temps. A cold engine w/key to on should measure 2 to 3 volts. A fully warmed engine measures about a half volt w/key to on at pin 2I.

Clark13b

Actually the 3000 rpm idle is really not something to be desired anyway. If you dont have it anymore thats a good thing. Turning on a cold motor and holding it at 3000 rpms cant be good for any rotary engine. The 3000 rpm warmup feature is meant to heat up the pre-cat to operating temperature.
Do you still have the old cats and exhaust? There is a chance they could be faulty and that could be causing your power loss when its running at operating temperature.
Also, a word of advice: Dont lay on the turbo if your engine is cold.
That is my humble opinion. Check your converters.

Th0m4s

Didn't know that below 60°F the engine won't idle fast. Good to know. Thanks. In Germany the temperature is round about 32°F in the morning. That explains it.

BUUUUUT i still got problems with my coolant temperature. For some strange reason my meters look like this when the engine is really hot->

I guess even for an S4 that's much too low and as you can see the idle is too high, too. Looks like the ecu is getting wrong signals. I allready exchanged my thermostat just in case it could be stuck but nothing changed so it has to be wrong signals. I'm going to recheck all the grounds tomorrow and to ground 2c and 2r with one wire for each of the pins but what else could I do?

By the way would the big long screw in the middle of the intake manifold be a good ground or should i better search a screw directly at the engine?

This car is going to make me crazy but no matter what happens: I'M GOING TO FIX IT!!!

satch

iTrader: (1)

The main engine ground is on top of the Upper Intake Mainfold to begin with.

The temp gauge normally would run a 1/4 to 1/3 at most. Perhaps the temp sender or gauge is showing signs of old age.

On the front of the throttle body is the throttle linkage. If you press upwards on it w/the car running and completely warmed up and the idle drops then its probably caused by the Fast Idle mechanism (located on the rear of the throttle body) that causes the car to idle at 1500 rpm after start up is out of spec. There is also an idle adjust screw on top of the Dynamic Chamber that helps to increase or decrease the idle a bit. When adjusting this screw the Initial Set Coupler nees to be jumpered.

Th0m4s

The problem is the temp sender worked some months ago when I got the car. Now after redoing the vacuum hoses it doesn't work anymore but nobody even touched it.

Today i finished the grounds. I regrounded the pins 3A and G and Pin 2C. When I tried to reground 2R my boost gauge stopped working.
Next thing I did was to rebuild the thick ground from the battery to the shock tower to the engine. I made a whole new cable for that purpose. 25mm² with soldered connectors.
After that I measured the resistance between the battery and the ecu. 0Ω everywhere but i stil got a hestiation at 3800rpm and I recognized I even got one near 6000rpm. The 3800 rpm hesitation is very strange now because it only appears in the third gear.

By the way I allways thought the water temperature sensor is the one between the waterpump and the thermostat with the green connector looking like an injector connector. I pulled it off today because i was curious what would happen without it. With that connector pulled off the gauge still showed that temperature like in the picture and the engine was idleing and starting like nothing happened. Was I pulling off the wrong sensor?

Another strange thing is that even fully warmed up the engine is showing no reaction at all if I turn the idle mixture resistor.

By the way i was trying the thing with the throttle linkage and the idle dropped a bit. maybe 300 rpm. Still not correct but better. In case the fast idle mechanism is out of spec, what could I do to fix that?

satch

iTrader: (1)

Some people regrounded the ground wire at the Boost Sensor in an attempt to fix the hesitation issue but might have regrounded the wrong wire so check the wires at the Boost sensor to see if this was indeed done. There are four wires at this sensor and 3 of them have voltage w/key to on while the fourth is the ground. B/W wire has 12 volts w/key to on. Brown/White has 5 volts w/key to on. Brown/Red has about 2 volts w/key to on. Last wire should be the ground wire. Check for another wire tapped into this wire.

Pin 3H and 3F are for the secondaries and both wires should have 12 volts w/key to on. If they don't then either the plug is loose on the injector or one if not both wires to each of these injectors is pulled back within the plug and not making good contact w/the injector.

With the TPS disconnected and the vacuum hose disconnected from the Boost Sensor and plugged it will trick the ECU into thinking the car is under load which is necessary to get the secondaries to fire. So while idling the car it can be free reved to fire the secondaries so rev above 3800 rpm and the voltage on the two secondary wires previously mentioned should drop down to about 8 volts from 12 volts as this indicates the injector drivers in the ECU are firing properly.

At the back of the throttle body is an upside down screw pressing against the Thermowax. Press the screw downwards and place a cap on top of the screw so it rests against the Thermowax. Use a cap about 1 inch in length so the screw is pressed downward as far as it can go. If the car idles lower then this mechanism is not set to spec properly. I will provide a link to how this Fast Idle mechanism is to be set.

https://www.rx7club.com/showthread.p...le+pics&page=4

The temp sender is located right by the Oil sender and not at the thermostat as that sensor is a thermo switch used to turn on the auxillary electric fan mounted up against the radiator. In redoing the vacuum hoses you might have dislodged the connector to the sender thus causing the problem. The vacuum hoses themselves have nothing to do with the operation of the sender or gauge so it must be something else.

The Initial Set Coupler needs to be jumpered when messing w/the idle adjust screw on top of the throttle body or the Vaiable Resistor.

Th0m4s

Thanks for your help again.
Going to look up the secondary injector connectors tomorrow. I didn't even think about loose pins inside but that could explain a lot.
Going to check that fast idle stuff tomorrow, too. I guess i will also have to check the water themo sensor and at the same time I will check my weird oil pressure gauge. i allready saw some strange things down there. Looks like somebody tried to rewire the oil pressure sensor and forgot to plug in the capacitor.

I read through the FSM about coolant stuff and they wrote about the thermostat that it should be fully open at 95°C (203°F) and start to open at round about 80°C (176°F). Is there any difference between the S4 and S5 ones? I'm asking because here in Germany they sell the same thermostates for both engines. I'm a little worried about that because the packaging of mine says opening temperature: 82°C. I don't know if that's the temperature when it's open completely or if it's the temperature when it starts opening.

A mechanic changed the thermostat 2 months ago because he thought the old one was broken because of the low temperature readings ( back then the temperatures were ok). The problem is there were many other things done to the car, too in the last two months and I wasn't able to drive it in that time so it could be many other things, too.

satch

iTrader: (1)

The Water Thermosensor and the Temp Switch are not related to the temp gauge but it is the sender near the Oil sender which the temp gauge is connected to.

Th0m4s

I just finished my work on the car and i think i found the problem. While in the garage to redo the vacuum hoses (which I better should have changed on my own) the mechanic also replaced the water hose from the intake manifold to the engine block with a universal hose. That new piece was folded in the middle and nearly no water was able to pass. Could that explain my weird temperatures? Is there a special shaped hose for that part which I should get at the dealer?

Next part of my problem was the connector of my BAC valve. One pin was pushed out of the connector. I put the pin back in and now i got the perfect idle. Can't thank you enough for the tip with those connectors satch.

Only my hesitation problem is still not fixed. The car runs great till 4000 rpm. Then (only sometimes) it starts bucking several times till 8000 rpm. Should I get new secondary injectors maybe? I checked the voltage and the connectors and everything seems to be ok.

satch

iTrader: (1)

If you're talking about the hose off of the back of the throttle body then it normally has a few predetermined kinks in it to fit so it's best that yours regardless of where you get it doesn't kink.

Did you try disconnecting the TPS plug and capping the vacuum hose to the Boost/Pressure sensor so you could free rev the car while parked to see if the hesitation still existed or not? The sensor w/the hose connected to it might also be out of spec. The Brown/Red wire at the sensor should have 3.5 to 4 volts w/key to on if the car is an non turbo and 2.3 to 2.7 volts if a turbo. Did you check to see if the wires to the Boost/Pressure sensor were wired improperly as in another ground added? Did you measure the voltage of these four wires to see if all were in spec?

satch

iTrader: (1)

And the wire to the temp sender is supposed to be Yellow/White.

And when you check for voltage on the Boost sensor output wire (2.3 to 2.7 volts w/key to on), the vacuum hose should be removed and capped.

Th0m4s

The hose is the one from the thermowax housing back to the engine i guess. I can't find it on allmazda.net. Do you know the part number? Because the guys here at the mazda dealer aren't really good in searching special parts...

I checked the boost sensor and it looks like nobody touched it yet.

I also did what you told me. No problem while standing. Even in the first gear there are no hesitations. The car starts bucking in the third gear with more than 4000 rpm and sometimes in the second gear with 6000+ rpm. Really strange behavior. It's like the more the engine has to work, the more it bucks around.

Which sensor do you mean with 3.5 to 4 volts which could be out of spec?

COuld that bucking also be damaged precats? should I try to remove them maybe?

satch

iTrader: (1)

Mazdatrix sells the part and has a pic of it on their site.

Free reving while in neutral is different than reving "after" the TPS is disconnected and vacuum hose capped. Not sure which one you did.

I forgot whether you had a turbo or not. Since you have a turbo the Boost sensor reads 2.3 to 2.7 volts w/key to on at the Brown/Red wire.

A clogged exhaust system could cause bogging issues.

Th0m4s

I did it like you said with disconnected tps and vacuum hose capped. Nothing bad happened.

I'm asking if the precat could be damaged because the changing of the vacuum hoses took several weeks and at least for 2 weeks the injectors were out, too. When the mechanic started the car again it was smoking thick black clouds for about half an hour. I think it was because they tried to find out if the injectors are good (had to clean the primary injectors) and some fuel, coolant and other stuff ran into the injector holes. As long as the car was smoking the exhaust headers were also glowing red. I remember the mechanic saying everything is ok and nothing can happen... I don't know if i should believe that.

satch

iTrader: (1)

I'm not really familiar w/the exhaust components though I think I read you should be able to look through a cat and see light coming from the other end and if not then it is clogged. A glowing exhaust could be caused by improper timing, too rich of a fuel mixture or a clogged cat. There's only so much I know.

I would go ahead and check the voltage as suggested at the Boost sensor as well.

Th0m4s

I'm such an idiot... I just figured out I forgot 1 ecu grounding wire. I mixed up 2A and 2C in my mind. Tried to ground 2A instead of 2C. I guess 2C is leading into nowhere now because i removed the old wire in the engine bay. Going to fix that tomorrow. That might be my last existing problem.

satch

iTrader: (1)

Pin 2A is the Vref voltage which runs to all the engine sensors and it has 5 volts w/key to on. Grounding this wire should cause things to act in a most peculiar fashion. Pin 2C also runs to all of the engine sensors but it is the ground for these sensors.

Th0m4s

Yep I know. I mixed them up. That's why my boost gauge didn't work when I grounded 2A. I changed it back immediately but I didn't ground 2C till now. It's going into nowhere. I will fix that tomorrow.

The engine is still running good for not having the 2C ground...

satch

iTrader: (1)

Not sure what you mean by going into nowhere. Does this mean the pin is not connected to the ECU? On a turbo, the ground from pin 2C ties into the ground from Pin 3A so if both factory crimps are good then 2C should be receiving a ground. If you checked the ground wire at an engine sensor w/key to on and it read zero then it should indicate that the ground wire is grounded.

Th0m4s

The problem is I regrounded 3A, 3G and 2R with 3 new wires because 3A was completely broken somewhere. I'm not using the 2 old ones anymore. I partially removed them today when the intake manifold was down. Only 2C still is connected to the rest of the old wire.

satch

iTrader: (1)

Where exactly did you connect these three new wires to the original wires as in the exact spot relative to the ECU? It needs to be done relatively close to the ECU or you'll end up bypassing some crimps which are related to the Oyxgen sensor.

Th0m4s

Now all 4 grounds are connected to the original wires right at the connector. By the way I found out somebody regrounded the shielding of the air flow meter to some screw next to the ecu. Should I redo that grounding maybe?

My 3800rpm hesitation is completely gone by the way but I have hesitations from round about 5000 rpm till 8000. The higher the gear, the more hesitations... It's getting more and more strange.

It also feels like i got at least 50 more hp now. The car is nearly driving as it should now. My only problem is that bucking. Maybe i should clean the secondary injectors...

satch

iTrader: (1)

Which wire (color) are you talking about? Are you sure it's not the Oxygen sensor? The Green/Yellow wire (Oxygen sensor) has a shielding that is crimped to pin 3G (Black wire).

Th0m4s

Yep sorry I meant the O2-sensor. It's not crimped to 3G anymore. It's connected to some random screw near the ecu.