gergrx7

Hey, i am wondering how the s4 TPS works, i know it only goes to 15% then it jstu says 100%. but does it tell the computer your at 50% throttle at like 7.5% or is it saying its at 7.5%? so at 100% adn above its just dumpign all fuel it has right? this sucks for highway driving, i cant keep it above 80 unless the throttle is over 15%(100% to the computer) are there any alternative TPS's. will an s5 tps work?

marlaman

ever think your tps might be bad? it happens frequently enough, perhaps find an s4 one and give that one a whirl, also do the fsm check to diagnose your tps, it could be possible yours has gone bad.
Matt

WAYNE88N/A

With the TPS disconnected, the ECU fail-safes to an 18* throttle setting, so that's probably what you're refering to. I do 80 mph ('bout 3300 rpm) down the freeway every day to work, and the only time I can get it to input WOT voltages to the ECU is when I'm jamming on her, so I think you're worrying a bit too much.

Hook a meter to its input at the ECU & you'll see everything the TPS is doing during cruise & WOT conditions...

gergrx7

so wait the s4 tps can tell a difference between 15%(actuall) adn like 50%(actual) bow if tps isnt connected to anything after it goes past 15%? i haev an safc, adn if i go to sensor check(in volts) will that be same as testign it ecu or should i be messuring it in ohms?

RETed

This is NORMAL.
Why are you trying to re-engineer system?
The Zenki FC3S TPS is called a "narrow range" TPS for a reason.
In fact, the Kouki FC3S TPS uses the same type of TPS control.
The Kouki FC3S TPS has two TPS's - one is the narrow-range and the other is the full range.
The narrow range TPS on the Kouki FC3S TPS is the same as a Zenki FC3S TPS.
The full range TPS on the Kouki FC3S TPS is ONLY used for the oil injection system.

The narrow range TPS goes 100% at around 1/3rd of travel of the gas pedal.
It is basically only used to trigger throttle transient fuel enrichment and some other minor solenoid systems.
It works.

I don't understand why you need to see a linear TPS output at 80mph???


-Ted

NZConvertible

Not entirely true. It's also used for transient fuel control (like a carb's accelerator pump) and for minor stuff like injector kill for unflooding and the A/C cut-off system.

RETed

Um, I'm pretty sure the full-range is only for the oil meter pump.
I don't think the S5 has an A/C kill system - I thought this was an exclusive FD3S function?


-Ted

NZConvertible

Don't you read the FSM Ted?

The injectors are disabled during cranking if the throttle is fully open (pages F1-48 or F2-44), and the A/C is cut for 7 seconds if throttle opening exceeds 55% (pages F1-74 or F2-77). The transient fuel info is from this SAE paper on the S5.

RETed

And where does it specifically state that these functions are dependent of the full-range TPS?
I can read, and I'm pretty sure it doesn't explicitly state this.
I KNOW it's not in the SAE paper.


-Ted

RXSevenSymphonies

iTrader: (2)

Ah it's a battle of the Gods!

NZConvertible

The full-range TPS does even more than I remembered. The FSM's Control System Relationship Chart lists as it an input for fuel injection amount, A/C control, boost control, ignition timing, and a few other things. Surprisingly the OMP isn't even mentioned.

The FSM says the accelerator pedal must be "fully depressed" for the un-flooding fuel cut to work. The narrow-range TPS cannot tell when the throttle is fully open, so it must come from a reading of the full-range TPS. If it came from the narrow-range TPS then this function would work at half-throttle, but AFAIK no S5 owner has said that it does. If an S5 owner proves me wrong I'll happily stand corrected.

The A/C cut occurs at a throttle opening of 50deg (not 55% as I stated before, my mistake). The narrow-range TPS cannot tell where the throttle is past 18deg, so this reading must come the full-range TPS.

In section III-3-a Optimisation of Transient Fuel Control on page 7 of the SAE paper titled New Technology Employed for the Latest 13B Rotary Engine it says:

"During the initial stage of acceleration, this new system first analyses engine RPM, the throttle opening and throttle opening changing rate, then commands the fuel injectors to shoot once only a precisely calculated amount of fuel into the cylinders."

While it doesn't specifically state that the full-range TPS provides this info, the narrow-range TPS would be totally unsuitable for this role so it's a pretty logical conclusion. I can't see how else this would work.

So as not to be accused of being completely off-topic, the info Ted posted about the S4 TPS is dead right. That's how it's supposed to work and there's no need to "upgrade" it. Swapping on the S5 TPS pair would be pointless because the S4 and S5 narrow-range TPS's are identical and S4 ECU has no full-range input. The only use an S4 would have for the S5 full-range TPS would be for a fuel controller with a throttle position input (like the S-AFC), but using the MAP sensor instead would be a lot easier. If it's faulty you need to replace it with another S4 one. Test it as per the FSM.

RETed

I would like to see this confirmed also.
I dunno if anyone can test this by disconnecting the narrow-range TPS section and just run the full-range TPS?
The starter fuel-cut at WOT can easily be confirmed.
Since the Kouki FC can run without the TPS being connected, I would try and drive the car to see how badly it drives.


That's right.
It doesn't explicitly state that.
After messing with Haltech's for almost 5 years now, there is very little throttle transient fuel enrichment at above 3kRPM.
This implies you don't need it at very high throttle inputs, which would be consistent with why Mazda didn't need a full-range TPS on the Zenki FC to handle such responsibilities.
In fact, K2RD has made the Zenki FC TPS work with Haltech installs even though it's not a full-range TPS.

Again, I would love to test this theory, but I don't have an S5 easily available to go messing with...


-Ted

NZConvertible

I regularly use more than 18deg throttle below 3000rpm, so there'd definitely be benefits to doing this with the full-range TPS.

If you read the section of that paper entirely if clearly implies that the S4 didn't have this system at all. It even says, "A new system has been added to the EGI system to improve fuel control", and graphically shows the effects on chamber pressure vs. time with and without the new system. This was probably added to overcome the inherent delay between the throttle opening and the AFM reading the increased airflow.

Given all this info, it does not seem at all logical for Mazda to have added a full-range TPS, developed a new fuel control strategy, and then used the least suitable TPS to implement it. Especially when the full-range TPS is definitely used for numerous other engine functions. It just makes no sense. It's not like they'd be the only manufacturer to do it.

gergrx7

so is it possible to put a full range on an s4? i know it reads form 0v-5v right? im going to be going with a microtech lt8. is it possible to find a full range tps off another car adn build a bracket adn what not and hook it up? i just want to beable to tune my car right. i dotn like crusing at over 15% adn the computer seeing 100%.