rotary_yankee

If the water thermo sensor is not connected would the car hesitation at full throttle only. b/c my car runs good but if i floor the pedal the car starts to have a hesitation where i can go faster. I also started to think it's my afm just because when i floor the throttle cable with my hand in the engine bay, when i let go of the throttle cable i heard a ping sound in the afm or intake filter. sound like a metal hitting against metal. please help and it's not the 3800 rpm hesitation.

there two sensor in a water pump i only have one connect. i believe the one connect is the highest sensor located on the water pump.


PLEASE HELP I WANT TO FEEL FULL BOOST. TRIED OF DRIVING LIKE A GRANDMA

sar

iTrader: (1)

Without the water thermo sensor your car will run extremely rich (as if the water temperature never warmed up). This would effect all performance levels some, but full throttle too. If you have the one by the alternator connected it may not be the problem, but at like $10 a sensor go ahead and buy new ones.

You have the old flapper door/barn style air flow meter in an 24 88 turbo II, the door closing quickly could have the sound of the spring or door metalics contacting.

Are you sure you don't have a boost or vacuum leak? Why are there loose plugs?

This is a fairly specific question and it's not like he's saying he has the 3688/3800 hesitation or complaining about fuel mileage without a thermo sensor. People know to search, if it's so easy help them out by finding it.

HAILERS

No. If the water thermo sensor becomes disconnected, the ECU defaults to 176*F. Once the car warms up it will run just as normal as can be.

If the water thermo sensor becomes disconnected, and the car is stone cold when you go to start it, it will be a bear to start.

I know this to be true because I read the recently download of the Training Manual that was posted on this site, plus I disconneced my water thermo sensor at the ECU and watched what happened using a digital meter with a duty cycle on it plus installing at the ECU, different resistors to represent different temperatures.

If you read the online FSM's you'll see the reference of the ECU defaulting to 176*, and if you read the Training Manual, you'll see that during START, the ECU recognizes the START mode from pin 3B on a series four, and the duty cycle of the injectors is set to the temperature of the Water Temp Sensor. A long duty cycle for cold water.......a short duty cycle for a hot engine. So since the ECU defaults to 176*F, then the duty cycle is SHORT and not enough fuel will be delivered, making for an almost non startable engine. IF you did get it started, then it'd be undrivable til the water temps get hot, to match the default temp of 176F.

http://wombat.sevarg.net/RX7/RX-7_Training_Manuals/

sar

iTrader: (1)

Interesting, you found something new for me; maybe it's just old bad ones that cause bad mileage then as they would read innacurately?

endneu913

iTrader: (5)

hmmm, interesting, im seeing a few connections here for me, and i may be crazy but bear with me.......... ive just dropped my ecu codes and its giving me the #3 code ( water thermo sensor) i was retrieving the codes because of an incident this morning when my car suddenly lost power at 4000 rpm..... once it hit 4 grand it was like constant 1/4 power, no sputtering or anything, and it happened in every gear... reading some of the above info sparked a few more issuse, Sar mention that the car would run extremely rich, which mine was doing as well. Couldnt pass smog at idle (hydrocarbons off the map) AND on top of that my cold start is hell!! ive kileld my battery just trying to start some mornings, im starting to see a correlation between th esmog and the cold start, but obviosly this coulndt have started teh 4000 rpm issue this morning as the other two issues have been ongoing......... so my next step is fixing the water thermo sensor........... anyone know how to do this, what it entails, it sound easy, i just havent ever read up on it...

HAILERS

Your almost but not really connecting all the dots.

Your water thermo sensor is probably unplugged or one of its wires is shorted to ground/open. It's only a two wire circuit. Fix it. If the circuit is good, then buy another sensor (I've never seen a bad one, but then I don't get around all that much).

A disconnected water thermo sensor will make the ECU default to approx 176* all day long. No more, no less.

A disconnected water thermo sensor will give you the symptom of a car that will hardly start when cold. That's easy to figure out. The RX-7 has a START map. It involves the water temperature, rpm under 500 and a 12vdc signal to pin 3B telling the ECU you are starting theh car.

Since the ECU is defaulted to 176*, then the ECU will pulse the injectors at say 10ms instead of say 45ms that a cold water temp of say 45* would give.

I've experimented with that water thermo sensor input to the ECU and I can guarantee you what I just wrote is the real deal. Now if you live in a area where the temps are in the mid sixties to seventy range, the starting won't be as severe if the water thermo sensor is disconnected, verses a 45* temperature.

You really need to back probe pin 2I (S4 car) and put the meter on volts dc. When cold the reading will be close to 3vdc depending on how cold it is, then as the car warms up the reading will steadily drop til when fully hot, the reading will be 0.45vdc to 0.50vdc, give or take a touch.

Look for the pug being disconnected at the back of the water pump housing. It's a green jack on the sensor. Two wires.

The wire at pin 2I is color coded green with a white stripe. Middle plug on the ECU. Green/white is the Lebanese color code for water.

https://www.rx7club.com/forum/attach...hmentid=150448