Camrann

Can someone please explain or link me to a thread, That explains all the parts/mechanisms/electronics used in keeping a good engine idle. I want this thing to idle well. Also on cold start it dies till warm. And it takes a few cranks to start. How do i get it to start up right away???? PLEASE HELP I am reall helpless in this area!!!!

Chuck

iTrader: (2)

There are so many things that will affect the idle, you almost have to take one at a time. The cold engine idle is affected by the thermowax adjustment. Vacuum leaks wil play havoc with idle. Make sure the throttle plate gaps are correctly set. Of course the TPS has to be adjusted but only after all this other stuff has been checked and properly adjusted. If your fuel filter is old and clogged, it will affect idle. Start with these.

Camrann

Why does my engine not start up on the first crank? Cant that be fixed??

Hazama

I'm having this exact same problem [and I cannot find it well documented anywhere, either]

I'm fairly new to the RX-7 community [and rotaries in general] but I do have a fairly good background in autos...

When I bought my car, the previous owner had said that the engine had been rebuilt about 4000 miles ago. I have no idea if that's true or not.


Anyway... when I do finally get the car started [after about three tries] it doesn't idle, either... and I keep having to rev it until the engine is hot enough to sustain a [very] rough idle. And then the check coolant light comes on. Oh man. It never ends, does it?

So yeah... I'm searching for the answer to this question as well... if I find one, I'll post it here... I'm about ready to replace all the hoses and give it a full tune up, but I don't know if that would even help at this point....


--- Haz

ilike2eatricers

Does it start up and then stall by itself? Have you checked your thermowax for the cold start problem?

Check the easy things first:
-vac leaks
-TPS
-timing
-clean/test BAC

Camrann

Ok, here is a question. I dont know what the thermowax is. Can u explain it to me?

Camrann

where is the "thermowax"

Chuck

iTrader: (2)

Thermowax....check the factory service manual. It explains what it is, where it is and how to set and adjust it.

asherwood

It is located on the Throttle body, closest to the firewall, it contains a wax substance that expands when heated, this causes a plunger to extend, when cooled, the plunger retracts to it's resting position.

The thermowax is responsible for adjusting the speed of idle from initial startup through the time that the engine reaches normal operating temperature. It does this by sensing the temperature of the engine coolant.

When it is cold the pluger is fully retracted (at it's cold position), at this stage the idle should be at it's highest and depending is the cold start systems is still in place and working, generally 3000 RPM. The throttle arm is resting on preset stops (cams) at the end of the shaft nearest the firewall.

As the engine coolant warms the thermowax, it's plunger extends and allows the throttle to slowly close therby reducing the idle speed as the engine warms. Eventually the throttle pin drops right off of the cam due to the full (warm) extension of the thermowax. At this point the ambient temperature of the area around the thermowax is above ~28 deg C

Of course now the actual idle speed is determined by throttle position settings, engine load, BAC valve etc.

All settings for the thermowax adjusting screw, throttle plate positions at temperature and TPS are best described in the FSM.

I just replaced mine because after 14 years it would no longer fully extend and drop the throttle shaft off of the fast idle cam, I have pictures of the thermowax if you are interested. The picture I have shows that the original couldn't match the extension characteristics of the new one! (No Viagra jokes please!)

Camrann

sure a pic would be great.
thanks.

Camrann

is the "FSM" The same as a haynes manual? cause the haynes says NOTHING about the thermowax.

Sideways7

iTrader: (7)

The FSM is the Factory Service Manual put out by mazda. It is very expensive (well over $100), but it can be found in PDF format at www.iluvmyrx7.com (sorry, i forgot how to do the encoding for the link)
On a side note, when it was colder outside my car would start then die immediately like yours. I never really figured out what the problem was, I just kinda dealt with it. The idle is pretty messed up on my car, too. I think the TPS is out of alignment, plus my injectors need cleaning and i might have a clogged fuel filter. Im sending the Injectors off tomorrow and I'm gonna fix the other stuff while its down. If the thread is still going, I'll update when all that is done.

Camrann

thanks sideways7.

Camrann

ok. Im sry guys. I dont know hardly anything about rotary engines. I really need some explanation. I looked int the FSM and didnt find anything about thermowax and how to set it. Please if i missed it show me where it is. Im so confused with all this idle mess. And the cold start. I just want my car to start up and idle correctly. And i will work through all the troubleshooting If someone will help me understand how to do it. I just dont understand. In all honesty.
-thanks in advance

Therx7ist

I wouldn't even worry about the thermowax yet. You are new to rotaries, so you just got this car? Did it run poorly when you got it?

Camrann

i just need some guidance. And explanation. Im trying to learn to do it on my own.

Therx7ist

understandable, but you need a starting point. Did it run fine and then change? Or has it always been a crappy idle

Camrann

The idle was off ever since i got it. And it died when u cold start it till it gets warm. And the temp gauge sat in the middle when it was warm. When it was warm it would idle. But it varried it bobbed up and down from about sometimes dying to 1,000. And sometimes pretty decent idle. steady at about 750rpm. It takes alot of cranks to get it started to??

ilike2eatricers

Have you check any of the codes yet?

Therx7ist

check the compression first, don't even go any further yet

Camrann

ok, how do i check the compression?

Camrann

Ok im buying a compression test. And test it. IM pretty sure the compression is good though. Because the engine was just rebuilt awhile back.

Therx7ist

all the more reason to suspect it. Who rebuilt it? The previous owner?

Camrann

Yes the previous owner. Im pretty sure he knew what he was doing

asherwood

Here ya go, as you can see even at the same temperature the 'old' unit does not
extend as far as the factory fresh one.

You should also be able to recognize the hose connections that are found closest to the firewall when the TB is mounted on the car.

One other thing, Atkins Rotary sells replacement Thermowax's for only $10, not sure if they are "functionally equivalent" to the factory unit though.

Al