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etiennekuh · Joined: 31 Jul 2008 Posts: 34 Location: netherlands

Hi,

I am currently building EFI on my 924, now the problem I have is mounting the TPS, I have a sensor that only turns one-way, so if I want to mount it it has to go on top of the intake manifold, but I am affraid dat the hood will destroy it if I close the hood to hard. someone any solution?

Etienne
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tuning is like a good hobby, it never gets bored

Min · Posted: Sun Jun 07, 2009 4:22 pm Post subject:

I just didn't use a TPS.

Min
_________________
Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting.

Martijnus · Joined: 29 Dec 2006 Posts: 2019 Location: Netherlands

the reason you can't mount it on the underside is that it only turns one way?

What ecu are you using? I'm sure if you switch the 5v and ground the tps will work the other way around...
Ecu can probably be programmed to work around it too... but swapping the wires should do the trick....
_________________
"Rule: Turbo's make torque, and torque makes fun." (C. Bell)

924 "50-jahre", 1981.
MSII/extra, LPG, ITB's, 5lug.
To be turbo'ed in a while.
Killed her at the Nurburgring, Porscheless at the moment

etiennekuh · Joined: 31 Jul 2008 Posts: 34 Location: netherlands

It is blocked one way. And I am using a KDFI so with MS software.

Is it possible to use it without TPS?

Etienne
_________________
tuning is like a good hobby, it never gets bored

Martijnus · Joined: 29 Dec 2006 Posts: 2019 Location: Netherlands

MS is capable of running without tps, if you base your calculations purely on MAP & RPM... which is the case in most of the applications.
Personally I use alphaN, which uses tps and rpm, because of my throttlebody setup.

You won't have accelleration enrichment and deceleration cut when you haven't got a tps.
_________________
"Rule: Turbo's make torque, and torque makes fun." (C. Bell)

924 "50-jahre", 1981.
MSII/extra, LPG, ITB's, 5lug.
To be turbo'ed in a while.
Killed her at the Nurburgring, Porscheless at the moment

etiennekuh · Joined: 31 Jul 2008 Posts: 34 Location: netherlands

I am going to look for a new TPS what will work the other way. has someone got some pics of how they have installed it? and any tips etc

etienne
_________________
tuning is like a good hobby, it never gets bored

pocketscience · Posted: Mon Jun 08, 2009 7:41 am Post subject:

This is how I installed my Haltech TPS on my Weber T... not pretty, but it's on the underside.

G.
_________________
Whoever said you can't buy happiness forgot about Porsche!
81 924 N/A, GTS lights, Saratoga, interior, headers, Integral cam, EFI (sold)
95 993
69 911

Min · Posted: Mon Jun 08, 2009 10:47 am Post subject:

RC · Joined: 25 Mar 2007 Posts: 2637 Location: Australia

Most TPS are spring loaded and therefore directional. Not a good idea to go against the direction since it minimizes play and resultant variations in readings. Fortunately they come in different directions, sizes and mounting alternatives so there are different options available. There is only 10mm clearance between the stock TB shaft nut and the hood. Better to mount underneath if using stock TB. Do search as Endwrench posted details of this mod and maybe others too.

There are different short cuts, omissions, and cheap fixes that can be taken, deleting the TPS is one of them. While the EFI system will still work, performance will suffer. You also lose the flood clear feature and maybe even some economy and drivability.

Without a TPS your only acceleration enrichment is by MAP dot, or the rate of change of the manifold pressure. When you want to accelerate you put your foot down, naturally. With old tech carbs a squirt of fuel minimises bogging down and permits faster RPM rise, if set up correctly. Putting your foot down also opens the TB butterfly to permit more airflow. Have a look at the following datalogs to see that the two factors are not simultaneous.

The TPS variation and TPSdot reading is instantaneous. It takes time for the air to get off its butt and move, like anything with mass. If you calculate the time difference it reads 223mS in this case. Thats a quarter of a second slower for a response without a TPS. Not earth shattering unless racing but certainly lets the ricer in the Hyundai get a head start. Found this figure is typical. Delay can be as "fast" as 0.1 seconds under boost to 0.3 - 0.4 seconds at low MAP, ie. idling. Thats where you really want quick acceleration enrichment!