I don't think thats a noob question. Why couldn't Mazda have designed the TPS as a non adjustable unit? A question I've been meaning to ask for awhile now.

 

Probably because our cars have so many funky things to control the idle, that adjusting one area affects the other.

I remember when we tried to lower the idle on Ian's AE using the throttle stop screw, it also increased the TPS resistance value from 1.0 to 1.3 kohms.

This in turn affected the drivability of his whole car. It was bucking like mad.

We had to fiddle with both for a while to get a 750 idle while still leaving enough travel for the TPS to properly fuel the car.

I think the TPS using only about 1/4 of its travel for the whole range 1v to 5v. That's really not a lot. So if something is even slightly out of whack, it causes problems. Giving it some adjustability is probably just a countermeasure.

 

Sure, but you would have thought Mazda would have taken all the above to account.

 

A LOT of things Mazda, especially the RX7 ,have done could have taken to account. Lists would a mile long.

 

Probably adjustable to make people pay service to have it recalibrated. The whole throttle body set up is a mess. I have no idea why they had to make it so complex. Then the S5's have the VDI to boot.

Freakin little spaceship like dashpot things hanging everywhere, hoses pokin' out. Bunch of springs, a double deck plenum. Fekin' absurd.

 

Pesky...those designers,eh?

 

If I were Mazda I'd hire a motorbike designer to take care of things like this. They constantly have to come up with clever packaging in limited space, they need to be innovative, and keep things as simple as possible at the same time.

 

Kinda like Occam's Razor!!!

 

Alright I looked up on this Occam's Razor thing, and one excerpt I found was:

one should not increase, beyond what is necessary

So, seeing as though our maximum set speed is 100kph in Ontario, I assume you'll be getting a limiter fitted to back off those mods on your car.

 

Is there one on any car that isn't adjustable? I haven't seen one.

 

The fact that it adjustable has got nothing to do with Mazda. All TPS's on all cars are adjustable. They have to be, because they need to be set very precisely. That's not something that can be achieved with mass-production tolerances without some form of adjustability.

The problem with the early Mazda plunger-type TPS is you're relying on a sprung screw to set it's position, which doesn't seem to be able to stay in one place very long. Most other cars made since the mid-80's used a rotary-type TPS that slides over the throttle shaft and is fixed to the TB. To adjust is you loosen its mounting screws, turn the whole unit until it's correctly set and then (here's the important bit) bolt it down tight, usually with two 10mm bolts. Much more reliable.

 

That's because you don't understand what half of it's for... That VDI is the main reason S5's have 14hp more than S4's. You'd prefer to lose that? Besides, variable length induction systems are very common these days. Mazda was one of the pioneers of idea.

 

I would think with a brand new TPS, my readings would be more consistent. However, I'm heavily weighing on the Thermowax to being the culprit. We'll see...

 

Thank for the self assesment you shrunken little kiwi. I was not saying that all those items don't have purposeful tasks, only that there must be a better way to extract the power out of the na without such a convoluted set up. Also I am very much aware of what the VDI does, I have an S5.

So it looks like your jumping off on a rant like you know me is infact very lame, and very

 

I'm glad you were able to kick off your argument so maturely... How would you do it then? Keep in mind that you have to meet all the laws and regulations that Mazda did regarding noise and emissions, plus make sure the car is reliable, easy to drive, not too thirsty, etc, etc, plus do it all with the technology of the time. That doesn't mean you fully understand it, otherwise you wouldn't have said "there must be a better way". As I said, variable length intakes are now very common. If there's a better way, why is it still being used? I get annoyed when people who admit they don't know what they're talking about refer to something as "absurd", when it was in fact necessary.
Also, I'm not sure what sexual orientation has to do with this discussion, but whatever...

 

NZ you so funny. I like how you approach matters maturelly

 

I didn't read the whole thread, so I am sorry if this has been answered.

The main reason the TPS is adjustable is because things wear. The throttle shaft, throttle lever, TPS itself, etc. All of them will wear down over time, changing the value of the TPS. Since the TPS is simply a slide pot, as the wiper rubs the carbon track it will also wear itself. So Mazda has made it (easily) adjustable to compensate for all these things.

 

Plus I'm sure if our TPS wasn't adjustable some of us would be bitching about that too...

 

All one needs to know about the VDI is that it opens at around 5000rpm. Simple.

What is absurd is that Mazda kept the same basic design for the engine since the inception. Finally with the Renesis they've made a design leap that really paid off. The variable length intake is to increase power across the whole rev band (like the 787b's), and the new types are dynamic in nature, unlike like Mazda's so they don't have much in common.

The Mazda system is aux porting, and it was overly complex and fragile. How many people have stuck 5th and 6th ports? Not that the ports aren't needed, but that they are prone to failure due to the method of actuation. How many people have to shell out massive money to replace the TPS's on S5's? How many people question the reliability of their thermopellet? It's foolishly complex, and the Renesis has proved that. The technology that's on the Renesis was very much available at the time.

All of those bits were necessary to make the 13b of the time run, yes. However, I am not questioning that; I am questioning why they designed it to require such an elabourate throttle/intake set up in the first place.

 

If you understood how it worked you wouldn't critisise it. I'm not even sure why you are. I very rarely hear people complain about it. Jeez, we're talking about a 17yo car. Critising it by comparing it to new car or race car technology is pointless. If you want new technology then go buy a new car. Wrong choice of words. The system is not complex and fragile, it is very simple and robust. Nothing breaks, it just gets stuck. It's not even that difficult to fix. Besides, how did we get onto the 6PI system? I can recall very few posts about replacing S5 TPS's. Because it dramatically improved performance! You make it sound like some Mazda aberation, both variable length intakes and variable cam timing or lift are now common in modern cars. Many have both. Even if you don't understand the engineering, this is more than enough proof that the system's are worth having.

 

Well said NZConvertible.

5th and 6th aux ports were V-TEC when V-TEC was still being worked on. Mazda is the only manufacturer working on roary engine in the world, while the rest of the world R+D goes into piston engines. They have been pretty creative and effective with what they've done.

 

um the big difference between the s5 and the renisis, is the exhaust ports, everything else is like the s5....

mike

 

I challenge anyone to have a consistant 1v @ Idle, repetitively. I'm begining to think It's damn near Impossible.

 

meh i just learned to live with the 0 idle and brake with the left foot.

i agree with j9fd3s when he says the major improvments are in the exhaust ports, but lots of the basics have been fidled with in the renesis as well (lighter rotors, better seals -all of em-, and the intake tract is similar to the s5, but the ports are bigger and come on in a **** load of stages comparativly. as for the technology being available to mazda in the 80s and earily 90s to do this, they tried.

the new exhaust ports on the side arent exactly "new" mid 80s mazda tried to do this exact thing, but the oil injection used to lube up our rotaries (remember, since then, we have made leaps and bounds on synthetic oils and such) always clogged the side ports forcing the team to dump the idea for the more clog-free exhaust ports you see now.

gosh i feel like im quoting from some article that i read like 3 months ago.....

 

My 2 cents is Mazda designed an innovative sports car.

They did not consider shade tree mechanics that don't want to spend a buck to have some one who knows what they are talking about fix something. And then they bitch about it.

Cars and women, (and dumb asses) you can't fix either one...although a little adjustment may help.

Keep rippin the **** out of your 7, someday mine will be worth a lot...
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