Hello,

car: 95 pep M/T

I rerouted my coolant line, bypassing the TB. Following robinette, I removed the spring from the waxrod screw, and screwed it in all the way to prop it up...


does this mean that my car will idle at 750 always, even when it first starts in 50deg weather?

I ask this because with the screw all the way in, the cam is not in contact with the roller---if i understand the operation correctly, it will only idle high while it is in contact.

(pg F-79 of the '94 FSM)
E.g. wax rod is retracted, cam is along the roller >> car warms up, wax rod extends, pushes on the screw, causes cam to roll down the roller, dropping RPM gradually >> wax rod fully extended, cam falls off the roller, idle is normal.


it just seems that with the screw tightened all the way down without a spring, it is the same as if the waxrod is fully extended. did I do something wrong?

Thanks!

 

Read the manual about how it works and play with the mechanism.
If you still can not figure it out, sell the car as the car is too smart for you.

Even without the water flowing through the unit, you can still adjust it so when the engine is cold,
it will slightly open the throttle and then closed it to normal when hot.

 

I always just think about the rotation of the thing. When it rotates upward, which off the top of my head is the same as tightening the screw, the fast idle disengages. This is basically carburetor type of technology. On modern cars, the electronic throttle does this function automatically.

When you take out the fast idle system on a 13B, you really only have two options. Idle high or idle low/possibly stall when cold. Some people care about that, some people don't. Honestly it's not really a "go to" mod I recommend on most cars. You might pick up an HP or two and save yourself a hose. The implications for idle annoy a lot of people over time.

And keep in mind that some of these writeups are something like 15+ years old... they're mostly accurate in how to do a mod, but they don't go deeply into a discussion of the advantages and disadvantages. I'm talking about things like the "fan mod switch" and other stuff that, while not necessarily bad writeups themselves, were created at a different time, when different parts and knowledge were around.

 

Even if you've completely disabled the fast idle cam, it should be possible to adjust the 'Air Adjusting Screw' so the car will idle low without stalling if the idle solenoid valve is disconnected. From there, if your standalone ECU lets you recalibrate the duty cycle for the idle solenoid valve, you should be able to get the the car to idle acceptably high when cold or warm.

On my setup (stock engine, AEM EMS), the thermowax valve is gone and the Air Adjusting Screw is adjusted so the car will idle around 700 RPM warm even with the idle solenoid valve disconnected, worst case scenario I don't want the car to stall too easily if there is a problem with the idle solenoid valve or its wiring. At high duty cycles, the idle solenoid valve can add enough airflow to increase the cold idle RPM above 2000 when coolant temps are 5-10C. I don't have to touch the gas to get the car started and idling even on the "coldest" days around here. You might run into trouble if you live somewhere that gets down to freezing temps, assuming you'd want to drive the RX-7 on those days in the first place.


Arghx posted a good photo of the Air Adjustment Screw location here:
https://www.rx7club.com/3rd-generati...-still-854524/

 

i've tried with and without the thermowax, and i like to keep it. however i do usually adjust it so that it doesn't idle as high/stay on as long as the factory adjustment.

i haven't messed with it much yet, but the FD looks like it might have two adjustments, 1 is the rpm it goes to cold, and the other is how long it stays there. they probably interact with each other, but you could probably get it to bump the idle to like 1200rpm for a minute or two, instead of 1800rpm and 65c

 

Cool guys thanks very much for the input. I will tweak and adjust as necessary. It seems that the way I have it set up right now just bypasses the fast idle all together, which yeah I pretty much agree with you on all points arghx.

scotty, unfortunately no standalone yet...will eventually go with apex'i

I'd like some clarity on this, if anyone happens to know:

The thermowax rod *does not* extend down if the coolant flow is bypassed. (true/false?)
or, will the ambient temps eventually cause it to extend down a bit?

 

it will not move enough without coolant flowing through it to do anything.

 

I see...so rerouting the line == disabling fast idle. Despite some previous posts, I think this makes a lot of sense.

in that case, I may as well remove the whole assembly! I have the car put all back together and my idle is ~1400. I am hoping this is just TPS out of whack. Moving the fast idle manually had no affect on the idle.


my store-bought hose could not bend well enough to accomodate the lower coolant flow from the TB, hence my current predicament. Too cheap/impatient for an OEM line (dont hate!). I will leave as is for now, try to adjust idle, and if cold starting is too rough I will go ahead and order that OE hose.


Thanks everyone for the input.

 

removing the coolant flow = permanent fast idle.

 

yes, of course..which is why you prop up/tie the cam

my bad