2.4 TB wiring mods

rabidh

That's quite interesting... If you figure out the ratio of resistances though (AG / (AG + AC)) they're very similar between the TBs, so I reckon we should be aiming for the same ratios:

closed + open
TB1:
Circuit 1: 0.557 + 0.302
Circuit 2: 0.439 + 0.731

TB2:
Circuit 1: 0.562 + 0.304
Circuit 2: 0.429 + 0.721

Maybe the 2.4 TBs have different resistances too? I could modify the spreadsheet so they can be measured and put in, then the correct values for resistors can be found for each TB?

edit: circuit 2 was upside-down

vocky

I've just measured a brand new 2.0 sc tb

(values reversed to match the opposite opening of the 2.2 + 2.4 tb's)

shut tight + closed + fully open

a-g 5.06k + 3.04k + 2.21k
a-c 2.16k + 4.17k + 5.0k
d-h 2.98k + 1.674k + 1.13k
d-b 1.111k + 2.427k + 2.965k

so thats a big differene between shut tight + closed :shock:

vocky

really need someone to measure the 'shut tight' resistance on a 2.4 tb

I will measure the shut tight values of the 'tb 1' in the above measurements

rabidh

Yep. It'd be interesting if we could see what other people's 2.4l TBs measure for fully open, normal and fully closed. If they all have different resistances too then it could be why the same set of resistor values don't work for all.

vocky

2.2 tb number 1

shut tight + closed + open

a-g 4.64k + 3.850k + 2.086k
a-c 2.137k + 3.060k + 4.830k
d-h 2.695k + 2.170k + 1.037k
d-b 1.09k + 1.698k + 2.820k

vocky

that makes the 'shut tight' difference between the 2.2 and 2.0 sc tb's....
g = 400 ohms
h = 295 ohms
just need the 2.4 'shut tight' figures to work out the resistance notsure.gif

Karlosfandango

how do I measure it, on ar or off car?

vocky

just disconnect the plug 🙂

you need to hold the butterfly shut, then measure a-g, a-c, d-h, d-b

it's a bit fiddly to do, easier with someone helping

if you can then also measure the normal position and fully open positions

Karlosfandango

a-g closed - 4.43
a-c closed - 1.94
d-h closed - 2.68
d-b closed - 1.03

a-g open - 3.77
a-c open - 2.60
d-h open - 2.25
d-b open - 1.47

a-g wide - 1.86
a-c wide - 4.49
d-h wide - 0.99
d-b wide - 2.72

vocky

so if we consider the 'shut' values all thats required is a single 200 ohm resistor on wire A :?

I wonder if that would work notsure.gif

rabidh

I'm not sure that would work :S I think that since B, C, G and H are connected to ground and power, the only thing the ECU measures is the voltage present of A and D. A resistor on A wouldn't change that at all...

I think it's back to putting various resistors on B, C, G and H... I'll try and work out what the best standard resistor values are with the new measurements...

rabidh

Karlos, those values looked pretty close to start with, it looked like the car would almost have run as it was... But fiddling with the spreadsheet I get:

150 ohms on G
150 ohms on C
50 Ohms on B
nothing on H

At lower throttle I could get them to match ok with those resistor values so it should idle ok, and I imagine at WOT it doesn't matter as much.

Karlosfandango

Progress!

The car started and idled without causing the eml light to come on. The throttle also worked normally, but when the throttle was opened randomly to around 3-4k the eml light came on and the throttle blipped from 1.5-2k rpm. The throttle pedal also stopped working at this point.

Muncher83

rabidh - have you tried those values yet?

karlos - what values was that using?

Karlosfandango

150,150,50 as mentioned above.

rabidh

Aww, close 🙁 Do you have an OBD code reader? It would be interesting to know what the ECU reckoned was wrong.
Is there any chance of trying the ones in the original spreadsheet?
0.37 G, 0.65 C, 0.4 B, 0.22 H
(download/file.php?id=28&mode=view)
You almost certainly won't get exact matches for those resistor values, so you'll have to go for the closest you can or use 1k potentiometers though...
Odd thing is that they are totally different to the ones from the last spreadsheet, but the only difference is before I was using sprung-closed to open, and now i'm using fully-closed to open. I'll have another play tonight and see if I can come up with some better values.
Muncher, I don't actually have a 2.4 TB! I was just interested in trying to solve the problem 🙂

Muncher83

If I go for the 1k pots, is it just a case of wiring each of them up and adjusting them to get the desired value? Is it easy to measure what you've set them to with them in situ? Electronics really isn't my field...

rabidh

Yep. you just have to unplug the throttle body and then put the meter across each pot. You probably know this, but the pots should have 3 wires, one of which is a wiper - if there's a diagram on the pot there will be 2 resistors drawn, and the terminal with both resistors on (rather than just one) is the wiper. You want to connect one wire to the wiper and one to a non-wiper.

Nice thing is that if you need to put the 2.2l TB back on you just set all the pots to 0 ohms and you're sorted. You'll probably want to buy a big-sized pot (about an inch diameter). You can get small multi-turn ones, but the big ones are probably easier to solder to and generally more suited to being in a car.

Muncher83

Great thanks, have you got a link to some suitable ones? I'm really not sure what i would need to buy.

rabidh

I've given up on excel and made a little program. Using Vocky's first measurements the 'best' standard (5%) resistor values to put in seem to be:

G 360 Ohms
C 620 Ohms
B 330 Ohms
H 180 Ohms

if you're using pots, you can set them to:

G 336.9 Ohms
C 588.7 Ohms
B 338.2 Ohms
H 180.9 Ohms

I'll post up in a bit what I get for the newest stuff using the full range of throttle body movement...

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