Like I said, I'm willing to learn. I guess I don't see why it would be so hard to put a reference marking on the flywheel and install in the proper orientation so it could measure crank position. It seems to me that this would be more efficient than having two separate pickups for crank speed and crank position.

 

The shaft position sensor is definitely on the front, behind the bottom pulley. The sensor has two wires, and at connector B1.27 they are Y/R & Y/B.

Mr. Buckeye is looking at the ring gear.
S

 

So your telling me were going to get more mpg and more horsepower?

I sure hope your right

 

Do you mean to tell me that the whole time we've been looking for a software solution that the problem is, in actuality, a mechanical one?? It would be great if it is but something doesn't add up.

The low(er) mileage and loss in horsepower and Mazda's changing of the rating for our cars from 250hp to 238hp indicates that this is an across the board type problem. I can't imagine that the manufacturing and assembly procedures are so poor as to allow every single RX-8 out the factory with defects on this pullyorwhateveritis. I'm still a bit skeptical. Hopeful, but skeptical.

 

i didn't say this is for sure your problem, but if you check the scope and see something strange happening to it then you found the prob.

the picture you showed us is for the starter to start the engine, that's not a pulse generator wheel

 

My screen name says it all. I was wondering if I was the only skeptical one. This just gives me the gut feeling along the lines of an "electric turbocharger" or one of those "power capacitors".

 

The loss of power i am talking about is not the 250 to 238 rated from the Mazda, i am talking about the loss of power of those guys that miss power all the way up to 9000.

I know it is strange and unbelieveble but my pulse generator wheel was bent, and i can't explain why.

It is somthing that spins with the engine and it seems impossible that it can loose it's concentricity, but i can tell you mine was almost oval!!!!

 

so how much of a HP/MPG gain did you get?

 

he is talkign about those individuals whose car is geting like 12-13 mpg and whos 8 is slower than other people's 8. he himself does no thave an 8 but he was experiencing really low mpg with his car and found this to be the answer for his car. he is suggesting that rx-8z which get extremely poor gas mileage may also have this problem with the triggger wheel

 

i had a aspirated 2.0 L 16 valves and it was supposed to deliver 154HP.
I was missing 25 corrected hp and nobody could explain my why.

After i replaced my trigger wheel i gained back was i was supposed to have.

I suggest to those that are in high fuel consumption to get the cope pattern and to compare it with those that don't have this problem at all.

Let me know
Simo

 

here is what is commonly called the trigger wheel for our cars. also known as the e-shaft position plate. remember the 20 brakes stomp reset also resets the eshaft position plate profile in the pcm memory.

 

yea i knew he didn't have our car i was just wondering what it did for his car.

 

i wasnt speaking directly to you GR8 just in general to the thread in case that was missed by some

 

oh ok lol

 

where is the e-shaft position plate located?

 

are those sine waves on that diagram what our o-scope reading is supposed to look like for the 8

 

well that must not affect me because while I do get poor mileage I think mine runs on the strong side power-wise, the low mileage is probably a right-foot control issue

 

it's called a flywheel, let's not start another "lower rocker arm" thread :D

 

LOL where did he get a starter from ? LOL
man where R/G

 

Yes that picture above shows the exat sinewave that an o-scope should show as the wheel turns. The wheel is not a 60-1 or 60-2. The most common wheels out there are 36-1 or 36-2 wheels. The RX-8 wheel is a 36-2-2-2. Look at the above picture to see how this works. Notice that each individual tooth is 10 degrees apart center to center. Since we only have 360 degrees in a full circle, we divide that number by the degrees of separation to arrive at 36 base number of teeth. However we see that there are flat spots. Notice that in the middle of these flat spots is what looks like the top of a tooth. It is. Also note that the teeth at the ends of these flat spots are exactly 30 degrees apart. Each tooth is measured from the center of the tooth to the center of the next. Since at least 5 degrees per side is going into the gap between the teeth, that leaves us with 20 usable degrees left in this large flat area. This means that we are missing 2 teeth per flat side. This shows up as the -2. There are 3 sides like this. -2-2-2. 36 base teeth, 3 gaps of -2 teeth = 36-2-2-2. Currently only the stock ecu or a Motececu can read this pattern as it is unique in the automotive world.

The ecu code is written to read these large areas without usable teeth but it also reads the number of teeth between these gaps. This is how it knows how to time the engine and also how to verify which rotor it is firing at. This whole sequence is only used to determine where top dead center is or more appropriately 5 degrees btdc is for both the front and rear rotor. That's all the trigger wheel does. The ecu uses this base as a starting point for which to start adjusting timing either advanced or retarded. If there is any problem with the way that the ecu sees the pattern of the teeth, the car will not run. It can't as the ecu is no longer getting the correct signal. Any problems would be located in the software and not with the wheel.

I could go on as to how this would or wouldn't have an effect on the car's performance but I am going to say that the reason some cars are getting bad mileage is not a result of the trigger wheel. Someone is really going to have direct verifiable proof before I will believe that. Sorry.

 

Thanks RG for the explanation. I was a bit skeptical but at the same time getting a little excited that the HP and MPG could be solved with a piece of hardware. Still, if someone could get their hands dirty and verify this, it would be great.

 

If someone could just get a reading and send it off to see what he has to say it would be great. I agree with RG though, it will take some hard proof to convince me that this is the problem. Thanks simo and RG.

 

Uh, lets see. No, no and no.

On older mid OBD-I cars, until right up to the end of the OBD-II, the crank angle sensor was one of two signals used to determine ignition timing. The other was typically on the distributor or camshaft.
Now it is done entirely by statistical prediction.
The e-shaft position plate is a really nifty way to get crank angle, but the engine wouldn't fire at all if any of the teeth were bent or missing because the PCM will go failsafe. It is really cranky about that (no pun intended). You can really toast a rotary engine under load with dodgy timing.

I'd be interested to hear what vehicle Simo is talking about, however.

 

hmm, this is interesting I'm going to look into this

 

Ahhhh I though the poor gas mileage and lower hp were contributed to the reprograming of the ecu so the engine runs rich? I thought Mazda did this to keep the cat from burning out?