There is no such thing as a 3800rpm hesitation....

 

this is incinuating that the 3800 rpm hesitation is a notchy staging in old and sticky injectors?

 

BTW.. a little fun information for the 3800 Brick Wall.. dunno if this has been gone over before...


I thought that my secondaries weren't kicking on because one of them was broken (at the connector).. turns out the connector I was looking at went to something else and both secondaries were plugged in correctly...

My brother-in-law spotted a cracked plug on the primaries... seems that if the computer can't read the primaries... then it'll run the secondaries instead as the primaries... After fixing the plug and getting the one primary injector back online... zoom zoom baby..

 

Ooh. So its the 3688 rpm hesitation.. I feel so much smarter today...

 

It is commonly referred to as a "3800" rpm hesitation because of the innacuracy of the stock tachometer which may be anywhere from a hundred to five hundred rpms off at different times throughout the rev range....

- chris

 

well... this is a silly thread

food for thought... possibly the reason everyone calls it 3800 is because the problems due to a lack of secondary injectors and diminished output from the primaries don't fully appear until the auxillary ports and/or vdi open shortly after (speculation) and REALLY throw off the A/F ratio.

 

well what ever it is i just fixed mine with a ground wire to the pressure sensor

 

No, the injector duty cycle halves when the crossover happens. Going from ~80% duty cycle on the primaries to ~40% duty cycle on the primaries will, if the secondaries don't kick in with their 40%, be an absolute brick wall.

-=Russ=-

 

Uh, I felt so much smarter a couple of weeks ago when arguing about the point the secondaries came on line. I know I said *around 3600rpm*.

I pulled the vac hose off the boost sensor and ran the engine up the scale. Watching the rpms on a Fluke, I could tell the stumble was at around 3600rpm NOT 3800rpm. Although it's maybe trivial, I'm/have been tired of hearing about 3800rpms. It ain't.

This is the first time I've seen it in print. Thank you.

*****Tell you what. XXX, If you will, try this for me. Pull the line off the boost sensor and plug it. Then with a fully warmed up engine, slowly rev above 3500 rpm in your driveway. You'll definitly feel a small stumble when the secondary injectors come on. I've done this with two seperate cars and it comes at approx 3640 rpm (Fluke and SAFC). I'm not making trouble, not being a hardhead (yeah, right), but that is the figure I come up with. Thank you.***********

 

i bet its really at 3688 and .897390874829347 rpms or some crazy number such as this lol

 

quit feeding the trolls...

 

I've always bought into this theory. When we rotor heads hear the term "3800 RPM hesitation" we know what it is refering to because we've heard of it often enough to know what to check to fix it. If all your dummy light came on, most of you would know that it is quite likely that the alternator is taking a ****. Its just one of the quirks of the RX-7. Why argue about the symantics of it? Fix it and drive on.

 

Hailers,

the common school of thought is "3800". Now that its been proven that it isnt 3800, then thats fine too, but due to the GROSSLY inaccurate nature of the FC tachometer, lots of people may interpret it as 3800. I am not debating your research, but i highly doubt the masses will start calling it the 3688 RPM hesitation overnight. In fact, that little peice of information, although very interesting, doesnt really change the way its handled.

But it is good to know..

Rat

 

this is all very amusing . . .

 

I thought the FSM stated "3800"...


-Ted

 

^

(if the FSM does indeed say 3800) typical corporate bureaucrats. one set of idiots has a completely different set of information from another set of idiots, hence two documents from mazda contradicting each other

 

The figure of 3668 comes from a Mazda manual found at this site under Fuel and Emissions http://wombat.sevarg.net/RX7/RX-7_Training_Manuals/

It's nearly the same figure I came up with using a digital meter and having the vacuum hose off the pressrue sensor, in a thread some weeks prior to the publishing of the http://wombat.sevarg.net/RX7/RX-7_Training_Manuals/

I'll agree it's RX trivia or a sort. Even the 87FSM indicates in the Fuel section that they come on at 3500 rpm.

Triva like calling a emissions harness a engine harness when they're two seperate items. Like calling Jack Jill.

 

"Eliminating" the pressure sensor messes up the fuel delivery, so I dunno why you all are pulling hoses in the first place. :P
That's not a very real-world simulation of what is exactly happening under real driving conditions. :P


-Ted

 

The manual at http://wombat.sevarg.net/RX7/RX-7_Training_Manuals/ does not take the vac input from the sensor. It's a statement on how the injectors work. Plus the figure matches what I've seen prior to ever reading that page out of the training manual. Coupled with the 87FSM fuel section info.

 

Someone must have been bored.