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Underbody braces, turbos and more!

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PostPosted: Mon Oct 02, 2006 6:08 pm 
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Joined: Sat Feb 04, 2006 6:49 pm
Posts: 116
Location: Zagreb, Croatia
Got a 55 mm Nissan TB a while ago.

First thing - it had a D type shaft, which I didn't wanna mess with much, and I had no original Nissan TPS:
Image

Fortunately, I came across the RS electronic catalog (something like Digikey in the US), with a pic of Wabash 971-0002 (http://www.wabashtech.com/pdf/WabashGeneric971.pdf) which had the D type shaft hole I needed - after checking the specs and comparing it to similar stuff, ordered it (costed me $50), did some measuring and concluded - it outputs the same resistance as stock TPS, only about 10% higher (starting from the same resistance at idle position, Wabash ouputs 10 % more resistance / voltage at WOT) - which could even be beneficial :
Image

Made an adapter plate for my new TPS (no pic, sorry :( ), and started thinking what to do with the idle switch ... so I removed the throttle stop screw, drilled a bigger hole and put in a plastic screw with a golden nail in the middle - the throttle shaft still has ground contact somehow (I love car electric, ground, beautiful ground, everywhere :lol: ), and it will provide a good enough ground signal in idle position:
Image

Then I moved the spring assembly from the Suzi TB, set the new stop screw to stick out 1.5 mm (stock was sticking 1.4 mm), adjusted TPS to give the same resistance at idle as stock TPS (around 700 ohm), and mounted the thing (sorry, image is a bit out of focus):
Image

No one could be more surprised than me when the car started, idled nicely, and responded to throttle without any problems :shock:

This is the best mod ever ... car feels so much better, stronger, responsive, you can just tap the throttle and hear the engine suck that air ... it's crazy, only now the cone filter makes sense. Yet the car is still perfectly driveable, idles nicely (although, I suspect a bit rich), and really responds to throttle ... the spontaneous smile just appears on your face at every green light ;)

And I'll never have to adjust the TPS, ever again:).

Enough typing, I'm going for a ride 8)

--
Bye,
chense


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PostPosted: Mon Oct 02, 2006 6:59 pm 
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Joined: Thu Apr 15, 2004 12:27 am
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Location: Aruba
chense wrote:
it outputs the same resistance as stock TPS, only about 10% higher (starting from the same resistance at idle position, Wabash ouputs 10 % more resistance / voltage at WOT) - which could even be beneficial


First of all, good write up!

Now, if the new tps outputs 10% higher resistance, does this mean that WOT comes in electronicly a bit earlier? If this is true, at WOT electronicly, the tb is not fully open yet.

Thanks

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1991-GTi: JE 75mm 11:1 pistons,Ported head, Single UD pulley (OCC),Sandros chip,Aluminium flywheel,3tech 222/365 cams, Cultus headers,Cultus IM,50mm tb,Crane cams adjustable cam gears,Apex suspension, 4.39fd GB.
1989-GTi: 3Tech 210/340 Cams,Cultus IM, B&G springs, TD04L turbo, Apexi SAFC, Suzukird UD pulley, Circuitse7en dual boost controller, AEM wideband, AEM water / meth injection kit, HKS bov.
2001-Altezza AS200: Stock.-sold
2003-EVO7 GT-A
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PostPosted: Mon Oct 02, 2006 8:24 pm 
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Joined: Mon May 27, 2002 11:47 pm
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Location: San Juan, Argentina
Resistance has nothing to do, but voltage does. The TPS could have been 1K, 5K, or 10K and the voltage reading should be the same at the same butterfly angle. Voltage reading should be similar.

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PostPosted: Tue Oct 03, 2006 6:20 am 
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Joined: Sat Feb 04, 2006 6:49 pm
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Location: Zagreb, Croatia
Hi,

@instant_shine - yes, with this setup the ECU would notice WOT (at least if ECU is even aware of WOT) when this larger TBs butterfly is not fully open (but very close to being fully open), and then even larger voltage when the butterfly is fully open.

Does this affect the amount of fuel ECU squirts at (real, physical) WOT? - I haven't noticed any ill effects yet.

@Caaarlo - yes, you're absolutely right, I was being terribly inprecise, sorry - off course the ECU measures voltage from the TPS, not its resistance ... and yes, the VOLTAGE reading is about 10% higher - starting from the same VOLTAGE at idle position, Wabash ouputs 10 % more VOLTAGE at WOT ;)


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PostPosted: Tue Oct 03, 2006 7:40 am 
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Location: San Juan, Argentina
There should be no problem though. Even the suzuki TPS have differences. The TPS is only used for transient acceleration enrichment and also for detecting Idle. The amount of fuel injected comes from the RPM and MAF readings.

I have been using a NISSAN KA24DE TPS along with the stock ECU, and worked fine. Any TPS with an IDLE switch can be made to work with the stock ECU.

BTW, I can only see 3 wires there. Where do you have the idle switch ?

EDIT: Sorry, I didn't read the whole post. I now realize you made some sort of switch using the stop screw.

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PostPosted: Wed Oct 04, 2006 4:52 am 
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Location: Zagreb, Croatia
Caaarlo wrote:
BTW, I can only see 3 wires there. Where do you have the idle switch ?

EDIT: Sorry, I didn't read the whole post. I now realize you made some sort of switch using the stop screw.


Yes, a nasty hack, but it works :lol: .

I had another idea - using the membrane that prevents the throttle from being closed to abruptly - the center metallic "axle" is also isolated from the ground, so when the throttle shaft assembly touches it, it efectively grounds it - so I was thinking about soldering a wire on that metallic "axle" and thus providing ground signal for the idle switch.
This way the ECU would see IDLE sooner than in my "nail in the throttle stop screw" scenario, and more like the factory setup (if the TPS is calibrated OK, the ECU sees IDLE when the throttle shaft assembly is 0.65 mm from the closed position).
Anywayz, I might still try it ... but this also works great (knock on wood) so far ...

--
Bye,
chense


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