Throttle body 3200 P0221

[andy15]

I am getting the P0221 code more and more often recently. (Throttle/Pedal Position Sensor / Switch "B" Circuit Range / Performance)
The TB has has been refurbished to contact-less, but as it was done before I owned the car, I have no idea who did it and how.
Initially I suspected the PP, so after I looked at it, have found new wires run directly to the ECU( this must be the solution for the ground problem that existed in some cars, I suppose). I checked the voltage on both of the signal wires and found almost no discrepancies between them.
Then I looked at the TB. From Engine Fuel Supply Manual page 82 I know the butterfly should move after turning the ignition to MAR. Mine does like on the video below. Not sure if this looks normal. Could some one advise, please? Any ideas?

https://drive.google.com/open?id=13p0gALPIYV-CdQpe7jLCWGiRojQEyuhA

Many thanks.

 

[Oneball]

Mine opens a small amount the closes quite quickly so looks the same.

With the ignition on but engine off the throttle will open when you press the pedal. So you can check for full throttle.

The new bit of wiring is probably the factory approved bypass of a loom connector to improve reliability.

Did you check the voltage both closed and open and ensured the two different circuits read the same?

 

[andy15]

Thanks Oneball.
I will definitely get this checked with opening the throttle. I did the video good few weeks ago, so don't actually remember if was it moving.
The voltage I did checked on open, closed and at few points in the middle and was OK. First I had 2 multi-meters connected and then I measured the differences between 2 output wires and there was something close to 0 V.
Another question - the noise coming out from the TB (like a high-pitch buzzing) - Is that also normal?

 

[Lozzer]

Another question - the noise coming out from the TB (like a high-pitch buzzing) - Is that also normal?

Mine does this with the ignition on, a sort of high pitched "singing" .

 

[Oneball]

Mine makes the noise too

I think the readings should be within 0.015v of each other or it gives a code. Says somewhere in the workshop manual.

 

[andy15]

0.015v- that's a bit tight. Not sure if was it that close... Will need to check again. And maybe should I connect 2 outputs together, just for a test?
Also didn't mention that earlier, but the car can't hold steady revs in range, c.a. 1300-2500 rpm. Any idea with that?

 

[davy83]

yes its tight and its one of the main problems with the pedal sensors is that Maserati were on the magic mushrooms when they designed this bit. I can confirm the two outputs need to be within 0.015v of each other at start up or you will get an error. Have you tried recalibrating the pedal sensor?
what do mean exactly that the car wont hold steady revs? is it hunting around while you are driving? To be honest this could be the pedal sensor or the throttle body. I do wonder if your throttle body just needs stripped and cleaned? The motor/magnet assemblies get gummed up after a while and it starts to stick a bit and this can make it tricky to drive. Does it run to high reves at start up and takes a bit to come down again?

 

[andy15]

...Magic mushrooms
Thanks davy83
When it starts it looks fine, doesn't go anywhere high, and stays at 800 (when is warmed up).
What I mean by not holding steady revs I mean that when it runs on 800, let's say, and I want to increase the throttle a bit to set at 1800 it will go further to 2500-2700, then I decrease a bit and goes down to 800 again. By extremely gentle movements sometimes it is possible to set it on 1500 (e.g.) but after awhile (10 sec.) it will go up again. It doesn't seems to be a problem when driving, just an observation when it's in Neutral/Parking.
The pedal calibration I do quite regularly, however I have never noticed any difference.

 

[davy83]

it should idle at 1000 rpm, so I am not sure why yours is idling at 800? if it's steady i guess its not a problem. I will try holding my car at 1300 rpm and see how steady I can hold it. My gut feeling is that i can hold it steady on the throttle, so the fact yours moves around seems odd. Having said that the ECU does mess around with the pedal to throttle connection quite a bit so I am not surprised its moving of its own accord.

 

[andy15]

Wow, ECU??? that doesn't sound good at all.
Have a look at the video. I would say it's quite steady, but still goes up and down a bit.
https://drive.google.com/open?id=1PnmZTTbFcKK_GDRAO33O1nuL_7YZB6Ef

 

[andy15]

It took me a while, but I have some more info and more queries too. The TB has been cleaned, lots of metalic powder removed from the magnet in side the step motor. After I've done that, I did pedal reset and the P0221 never came back. So now the suspect is the pedal pot. I measured the voltage difference between white and yellow wires and with the pedal rested it's 0.027V (and no errors or limp mode). The output voltage with pedal rested was around 0.45V. On pressing the pedal, the difference was dropping a bit and went below 15mV at 1.6V.
I also had the 2 wires joined but it didn't make much change to the revs being not steady.
But I have one more suspect. Just yesterday i noticed that both check valves are removed from the oil recovery system. I mean the small one on a tubing to the intake manifold and the other one from catch tank to the filter box. Could that cause the problems with revs?


Wysłane z mojego motorola one vision przy użyciu Tapatalka

 

[Contigo]

Check for vacuum leaks at the bulk head behind the back of the engine. Also the pipes that run to the Turbo's too. And idling issues are nornally related to vacuum leaks.

That rest voltage seems low from the workshop manual it states 350-600mv




Do a simple measurement afterwards between the connected wires and ground with a good digital voltmeter. Ingintion on, engine NOT running, NO throttle. Should be 350mv-600mv.
If so, the pedalpot will do the job.


pins 2 and 5 are common (5v) and pins 6 and 3 are common (0v) if you are taking any measurements. Pin 1 is the output from one of the sensors (2) and pin4 is the other sensor output (1) all the wires should be connected though according to the wiring diagram.

Pin 2 on ECU -----> Accelerator pedal signal 2.
Pin 8 on ECU -----> Accelerator Pedal signal 1.
Pin 21 on ECU-----> TPS 5V supply.
Ping 34 on ECU ----> 5 V reference.

 

[andy15]

Thanks Contigo
The vacuum leaks were all checked and repaired when I had the manifold out. Turbo hoses checked too
The rest voltage is 450mV, so within the range. I will measure again with white and yellow connected. I guess this will give the higher value of the 2 output values. I'm also thinking of using only 1 output and split it into 2 ECU inputs - what do you think?

 

[Contigo]

Is it a standard Bosch pedal pot or is it an aftermarket sensor? I'm a little cautious about doing the mod on an auto car to be honest but it should be fine, I just think if there is a spike in the signal then it will take that voltage for both and send the acclerator open fully!

 

[andy15]

This is a standard one. I am aware of that and not too keen to do it as well, but it will be for a test purpose only. I wouldn't be too happy driving it all the time like that. The car can be scary enough without that mod .

 

[alfatwo]

It'll be your throttle body Andy, I had the same on mine

David Askew's JLR R&D man reconditioned mine , never had a problem since!

Dave

 

[davy83]

I am not sure why but your idle speed is too low. It should be 1000 rpm so the idle at 840 rpm is a problem. it has to be either throttle body not responding properly, or the engine speed sensor is on the blink, it wil lidle at 1000 rpm regardless of what the pedal sensor is doing, even if its disconnected.

Wow, ECU??? that doesn't sound good at all.
Have a look at the video. I would say it's quite steady, but still goes up and down a bit.
https://drive.google.com/open?id=1PnmZTTbFcKK_GDRAO33O1nuL_7YZB6Ef

 

[andy15]

Just did some tests again and with the PP disconnected it's still a bit low and the throttle butterfly keeps moving slightly. The speed sensor does make a sense. I will go this track now. I made a video with the PP output voltage (white and yellow connected) and the revs gauge. Holding the pedal steady, but revs go high up. I don't think now that the PP is faulty.

New video by Andrzej Szala

photos.app.goo.gl

And here is a short one when idling. This one is with the PP connected, but was exactly the same with whole plug disconnected:

New video by Andrzej Szala

photos.app.goo.gl

 

[davy83]

At least you know the pedal sensor is not causing the fluctuations. i did replace the speed sensor on the crank on my car early on as it was part of my problem list. normally fluctuation like this is most often either normal or throttle body related, but its not uncommon to have several things slightly faulty and all contributing to a larger problem.

Just did some tests again and with the PP disconnected it's still a bit low and the throttle butterfly keeps moving slightly. The speed sensor does make a sense. I will go this track now. I made a video with the PP output voltage (white and yellow connected) and the revs gauge. Holding the pedal steady, but revs go high up. I don't think now that the PP is faulty.

New video by Andrzej Szala

photos.app.goo.gl

And here is a short one when idling. This one is with the PP connected, but was exactly the same with whole plug disconnected:

New video by Andrzej Szala

photos.app.goo.gl

 

[davy83]

have you checked the engine RPM with a strobe light or some other method in case your RPM dial is just out a bit?