Valkyrie

I noticed that there seems to be quite a bit of difference in tension between the point at which the cable starts to move the throttle, and when the secondary (or primary?) plates start to open. I notice that this seems to be the point at which I have a lot of stumbling and un-smoothness (mainly because my dashpot is trashed), even though my TPS is in perfect condition, and properly adjusted.

I think this might be the same as the spot where the short-range TPS switches out to the full-range TPS, but I'm not sure.

I wonder if there's anything you can do to smooth out this transition? I noticed that even though I unscrewed the top throttle stop, it didn't really change position (at all), but I can't remember where the other throttle stop is, or whether it would really change anything (it's probably set to null as well anyway).

(Maybe I should check the throttle clearance of the 1st secondary? It's in the FSM...)

There are times where shakiness might just be old shocks, but there are is also a spot on the throttle (it's at near-zero throttle, more than likely the transition point) where it pulses, which when out of gear just makes it go up and down, but when it's being driven at low speed, especially in 1st and 2nd, that translates into bucking, which is kind of embarassing (makes the person you're driving around think you're an idiot, or that something is wrong with the car).

But as I said, there are no dead spots in the TPS (I've checked over and over again).

drago86

It is suppost to be like that, only the primary ports are used during part throttle (~30%) for gas mileage. The dashpot controls the closing, not the opening. Stumbling could be the common 3800 rpm hesitation or variation there of, there are many thread on how to fix this, feel free to search.


*edit: actually, reading more closely, it just sounds like the TPS is out of adjustment, there are many threads on how to adjust the tps, also the "top throttle" stop is just an air bypass used to set the idle speed.

Valkyrie

I know what the dashpot is for... it simply doesn't control the closing of the throttle properly (since it's basically stuck in, unless I unscrew it and let it sit by itself for a few days, in which case it'll come back out, but it still won't work for long).

But not having the throttle dampened hurts the on-off throttle transitions a bit.

The stumbling definately isn't a hesitation... just a funky spot on the throttle that shouldn't be there, especially around the area of the transition.

And that throttle stop screw isn't used for setting the idle (unless you want to idle at about 4000 RPMs), since it only controls the secondary throttles (at least, the one on top isn't).

Valkyrie

Also note that 90% of the TPS adjustment tutorials out there are meant for S4's, or turbos. The S5 connectors are very different, although the principle is essentially the same (you watch the resistance for the narrow-range sensor and turn the screw till it's at 1K ohms on a hot car. The pins you want are the top and bottom right. Wide range is top left and bottom middle.).

I suppose I'll try the light method...eventually. I did in a way before, just by watching the voltage on the two pins (watching for one of them go to zero). That seemed to work ok... but didn't seem nearly as precise.

SureShot

You can have the TPS adjusted perfectly, but it may have a bad spot just above closed throttle. That's where most of the normal driving wear happens.

Pull the plug & clip an analog (cheap needle type) ohmmeter on the green & orange wires.
Slowly work the throttle & look for jumps in the sweep of the needle.
I'll bet you can guess what the ECU does when it sees one of those jumps..

drago86

The screw directly on top of the TB isnt a throttle stop, just an air bypass, check the FSM if you dont believe me. The secondaries are suppost to be completely closed at idle. The only way to adjust the throttle stop for the secondaries is to bend the throttle stop tab.


I use the check light tps method and it works great for me, it also works perfectly on both gens/na/turbo. 1/8th a turn passed one light seems perfect.


http://www.rx7city.com/89-91manual.htm


^^^^ the FSM has all the idle adjustment procedures, and what all the screws/connectors on the TB actually do. The tps procedure is near the bottom.


I run without a daspot and have no on/off throttle harshness.

Valkyrie

I wasn't talking about that screw... I know that's the idle adjust. I meant the hard throttle stop one on the side.