Alfa Pages

JeremyC · Last edited by JeremyC on Sat Jun 25, 2011 4:17 pm; edited 1 time in total

Am I correct in understanding that the tps fitted to the front of the right hand side tb is, effectively, two switches. One of these switches is closed when the throttle is closed the other when it is fully open.

Presumably the third pin is a 12v supply and when one or the other of the switches is closed you get 12v out on one of the other two pins?

Presumably adjustment involves rotating it until you get an appropriate signal when the throttle is closed? Should it shut off instantly the throttle opens by the tiniest of amount?

Presumably (again) there is no further independant adjustment for fully open sensing?

Thanks, as ever, for your input.
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'93 Black 33 1.7 16v

lee16v · Posted: Fri May 27, 2011 1:26 pm Post subject:

I presume you are correct JC.

My tps switches as soon as the throttle moves although I'm not saying this is correct....that's just what it does on mine and I've never adjusted it.

BigAl · P4 Joined: 06 May 2003 Posts: 2995 Location: U.K Surrey

It should be as you have said.
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x2 33 16v
pictures http://www.alfa-pages.co.uk/viewtopic.php?t=5203

JeremyC · Posted: Fri May 27, 2011 2:11 pm Post subject:

Al, you're a star, I shall save that away somewhere safe.
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'93 Black 33 1.7 16v

BigAl · P4 Joined: 06 May 2003 Posts: 2995 Location: U.K Surrey

NP JC,
I didn't know if that was too much info or just enough Smile

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x2 33 16v
pictures http://www.alfa-pages.co.uk/viewtopic.php?t=5203

JeremyC · Posted: Fri May 27, 2011 2:43 pm Post subject:

I have a (very dusty and unused) degree in electronic engineering so it was perfect thanks. Graphs are good!

The injector cleaning hasn't made the hesitation go away so the tps is the next candidate.
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'93 Black 33 1.7 16v

BigAl · P4 Joined: 06 May 2003 Posts: 2995 Location: U.K Surrey

Have you tried running with no lambda connected?

I'll go a little technical here for a minute.

When the ECU switch from closed / open loop for the lambda sensor or from TPS open or closed it cuts off the injectors, there is normally a jerkyness.

When I switched out the relay to tell the ECU that I don't have a Lambda sensor, the transitions were much smoother.

Also the ECU and AFM can be callibrated for when a different ECU or AFM is used. You tell the ECU to ignore the lambda sensors readings and it allows you to use the POT on the AFM, you can then adjust the CO2 to a range of 0.6 - 1.0 before the cat, when you have finished tell the ECU that you using the lambda sensor and bobs your uncle.

I can only assume that the ECU needs a correctly adjusted baseline for it to make the fueling adjustments and if that baseline is out then there is a larger difference leading to jerkyness.
Hope that helps Smile

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x2 33 16v
pictures http://www.alfa-pages.co.uk/viewtopic.php?t=5203

ZeNiTh-PbArM · Posted: Sat May 28, 2011 12:01 pm Post subject:

Hi, are you guys absolutely positive that the TPS described is the one fitted to 16V's? I seem to recollect that all 16Vs were fitted with the Bosch ML4.1 system, where the TPS is not of the resistive type but contains two microswitches, one for idle position and th other for full throttle position.
Resistive TPS were fitted to 1.3 with Weber-Marelli fuel system.

Regards,
zp

BigAl · P4 Joined: 06 May 2003 Posts: 2995 Location: U.K Surrey

I think so, I have one here i can test Smile

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x2 33 16v
pictures http://www.alfa-pages.co.uk/viewtopic.php?t=5203

JeremyC · Posted: Sat May 28, 2011 4:47 pm Post subject:

That's what I had believed ZP but my TPS looks like the one at the top of Al's posting.
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'93 Black 33 1.7 16v

bobbber · Posted: Sat May 28, 2011 8:38 pm Post subject:

it's switched! not a resistor.

kids of today...
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Fiat Bravo 165 Sport

JeremyC · Posted: Sat May 28, 2011 9:40 pm Post subject:

Now I'm confused!!!

So does Al's manual extract apply to earlier cars?
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'93 Black 33 1.7 16v

bobbber · Posted: Sat May 28, 2011 9:47 pm Post subject:

there are several sections, one for each type of fuel injection system.

turn the switch and listen for the click!
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Fiat Bravo 165 Sport

bobbber · Posted: Sat May 28, 2011 9:51 pm Post subject:

bear in mind there were several injection systems in use, depending on engine size, cat configuration and also intended market. some are early, some late, many ran concurrently. it's a confusing old bunch!
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Fiat Bravo 165 Sport

bobbber · Posted: Sat May 28, 2011 10:08 pm Post subject:

I'm with zp on this one... I don't think I've seen a 16v with variable tps.

I'd send you the manual, but I'm on holiday until Monday... then I'm on holiday Laughing

The "Alfa info", link at the top of these pages (then "fuel injection")... gives a good overview of the systems in use.

I'd like to give a +1 to these actually as underrated and often overlooked.

b
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Fiat Bravo 165 Sport

JeremyC · Posted: Sun Jun 12, 2011 11:05 pm Post subject:

Just fitted my new TPS and adjusted it to be in the same position as the last one but I'd like to fine tune it.

How do I get a meter onto it's terminals. Presumably there are three pins in the ECU connector I can use, anyone know which they are? Alternatively is anyone breaking a car at the moment and can they spare the connector and the short bit of loom so I can make a test connector.
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'93 Black 33 1.7 16v

JeremyC · Posted: Sat Jun 25, 2011 4:21 pm Post subject:

OK, I bought a spare 3 pin JPC and made up a test harness. My TPS is going from closed circuit to open circuit with the tiniest of throttle movements. It is almost impossible to move it at either the pedal or the quadrant (that converts cable movement into shaft movement) without it going OC.

I presume this is correct?

At the moment, though I've yet to get the car really hot, the new TPS seems to have fixed the hesitation.
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'93 Black 33 1.7 16v

bobbber · Posted: Sat Jun 25, 2011 7:29 pm Post subject:

That's the idea! the slightest touch should change the switch.

Although make sure it's not too sensitive, or it will cut out the compensation before the throttlebody is open at all! you will know if it's like this as a tiny amount of throttle will stop the engine.

Good luck!

b
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Fiat Bravo 165 Sport