Quick Throttle Body Question (Petrol Xantia)

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addo
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Quick Throttle Body Question (Petrol Xantia)

Post by addo »

I'm looking for help clarifying which plug is which (other than the idle air controller).

There's a yellow one on top.

Then a whitish one underneath, and also (feels like) a greenish one, too.

One is the TPS. One is the IAT. What is the last of the three?


This all comes back to the AL4. I've realised that the harshest 3-2 downshifts happen at almost no throttle opening, when gently slowing from about 30MPH. So, I'm thinking the electronics aren't quite reading throttle position correctly. Perhaps something needs cleaning in the TPS?

Cheers, Adam.

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Post by AndersDK »

Injector ?

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Post by citronut »

how dose greenish feel addo TEA HE

regards malcolm

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Post by addo »

Greenish feels like purple tastes. :P

Perhaps we can try duelling spoonerisms another time? :lol:

Below is the yellow connector, also showing the IAC wiring. While I found the yellow plug on the ECU schematic (p.247) I can't decipher its tiny emblem. Looks like a steaming hot sausage on a stick.

Image

Now we have the creamy connector for the TPS (I think), showing slightly the greenish plug behind.

Image

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VertVega
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Post by VertVega »

Hi addo,

Yellow: connector is the reheating unit.
White: That's the potentiometer (Throttle Position Sensor)
Green:??? Don't know and can't see. color blind :)

In the throttle body there is one more connector (GRAY in mine) which goes to the temperature sensor. That connector is near by the yellow one.

I will try to find some pictures.

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Post by VertVega »

I had this throttle body which I got some years ago from a scrap yard for free (I was only looking for an Idle motor).
This is from a petrol engine XU10J4R, same as in mine.
I took a picture where the important components can be seen.

Image

The potentiometer was broken. So I removed the broken cover away to see the inside structure.
This picture might be interesting. Between min and max the rotation is 90 degrees.
You can see how the slider moves from min towards max between the two pictures.

Image

.

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Post by addo »

Great pictures, thanks. I'll have to do some more investigating on mine but you have confirmed that other peoples' remarks that the TPS was just an on/off switch are wholly incorrect.

It lurched and kicked down this week in exactly the way I feared would happen, mid-roundabout at modest speed. :shock: An unfamiliar driver could have really panicked.

It may be a silly question, but did you measure the two resistive tracks against degrees of rotation?

Cheers, Adam.

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Post by VertVega »

Sorry, I never had to measure or deal with the TPS. No problems so far :)
TPS is absolutely a potentiometer (like a light dimmer).
I don't know the meas. values.

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Post by addo »

No probs; I'll measure mine in about a week and post results. Until the 405 is on the road, I'm not keen to dismantle the only running car. :lol:

Thanks again for the pics; unbelieveably helpful and confidence inspiring.

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Post by VertVega »

addo, does your car sometimes hesitate and kick/shake on a constant speed or on constant speed you feel lack of power (like cycling against wind :) ) and press the gas pedal more.
If you say yes then I would suggest you to check the MAP sensor which is under the intake manifold. I had to change it once.

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Post by addo »

The best way to describe the issue, is that at extremely light accelerator position and around 40-50 km/h, it suddenly and roughly changes down to 2nd. The whole powertrain lurches in its motor mounts (I have photos of the chafing and it also stresses the fuel feed line).

Before my ownership, the car was driven exclusively in the city for 100K.

Right now it is a little thirsty at 11.26/100km with corrected data, but I'm thinking the O2 sensor (still original at 125K) may need replacement.

Image Image

Here you can see the extra plug on the TPS (via mirror). I was guessing green by feel, but in daylight it is blue.

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CitroJim
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Post by CitroJim »

Hi Adam,

A green connector is normally the knock sensor...

I can't think of any green connector on any throttle body I've seen but there's always a first time...

The knock sensor connector is normally a little distant of the sensor itself (screwed onto the block) as it has a fly-lead on it. The knock sensor is in fact a little microphone that "listens" for knocking!

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Post by addo »

G'day Jim, it is one of the "knock sensor delete" versions - they dropped this part at the beginning of 1999, I think. The plug is still there on the harness, flapping around above the VSS.

Per your Bosch 5.1 diagram I can't find the blue (not green) plug, so perhaps it is for the AL4?

Regards, Adam.

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Post by Stempy »

This may or may not be helpful, but when I first got my AX it had a similar problem in that at certain throttle settings it would lurch and shake the whole car ( almost enough to change gear even on the manual geabox! ). Investigation traced the fault to the TPS having a worn track. I had to replace the entire throttle body though as the TPS is integral.

It was clearly worn when I dismantled it and showed up as a glitch when measured through its range on an ohms meter.

I have a slightly similar problem with my V6 in that the 4HP20 will sometimes bang into gear when you demand power at very low speed, usually after braking for a junction for example. I've changed the TPS though so it's not that.

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Post by CitroJim »

Stempy wrote: I have a slightly similar problem with my V6 in that the 4HP20 will sometimes bang into gear when you demand power at very low speed, usually after braking for a junction for example. I've changed the TPS though so it's not that.
I'll have a look into that Stempy. I've a feeling the 4HP20 ECU takes a lot of various signals to come to it's conclusions about which gear to select and when.

Have you seen the lastest in my V6 blog? You can see a 4HP20 in bits in my workshop :D