Power steering readings. Do you seeanything strange?

[dm222]

Hello,

 

My power sterring pump was replaced twice and my steering seems to be harder and then lighter sometimes, I made some readings in my PAS system, do you see anything strange?

 

This was made at night with headlights turned on.

 

Look at the column Steer. Aid Sensor Reference Voltage is empty, but the sensor is working what that means? Is it normal? What about the battery voltage?

 

https://drive.google.com/file/d/0B5pgma4HYX7dUEJKMGFLSF92WDdDY01aaV96SWg2VnJwN3lV/view?usp=sharing

 

Thank you.

Edited 10 August, 2015 by dm222

[Breezy_Pete]

Here's a log I took on the way to work this morning (headlights on, for fair comparison, even though unnecessary).  It doesn't have quite as many columns as yours, just MBs1 and 2.  I can have more of a look at lunchtime if you want. Data looks approx. similar, I think?

 

Edit: Actually, your pump seems to run about 50% faster (than mine) when the sensor isn't showing any steering input. Not sure what that indicates.

[dm222]

Thank you Wino.

I believe the pump speed when the sensor isn't showing any steering input it's related to the car speed, at the first seconds yours works at the same speed as mine.

I will check the rpm at more speed after work.

 

In mine the column Steer. Aid Sensor Reference Voltage is always empty, but the sensor is working, is it normal? I think it should show "Correct" if it's all OK or "Too Low" if there is a problem in this column but mine is blank.

Edited 11 August, 2015 by dm222

[Breezy_Pete]

Ah, OK, that would make sense, my journey starts in a 30mph zone, then after a few minutes changes to 40mph limit, and flows better for the later stage of the journey, so that would fit with what you say.

 

I'll look at that measuring block in a couple of hours time.  I think the Koyo version of the PAS system uses a sensor with four connected wires, so it might be that the reference voltage is used on that, but not on the TRW 3-wire sensor?

[dm222]

Ah, OK, that would make sense, my journey starts in a 30mph zone, then after a few minutes changes to 40mph limit, and flows better for the later stage of the journey, so that would fit with what you say.

 

I'll look at that measuring block in a couple of hours time.  I think the Koyo version of the PAS system uses a sensor with four connected wires, so it might be that the reference voltage is used on that, but not on the TRW 3-wire sensor?

 

Mine is 3 Wire, but when the previous pump was bad I saw once "Error" on that field so I think the TRW uses that too. I took a print screen at the time.

 

Edited 11 August, 2015 by dm222

[Breezy_Pete]

I just did another 5 minute log, with MB4 too, the third column just says "Too Low" in every cell.

My pump has run for 4640 hours apparently, which translates to a lifetime average speed of the vehicle of about 26mph!

 

I'll upload the file shortly.

 

Here you go.

[dm222]

I just did another 5 minute log, with MB4 too, the third column just says "Too Low" in every cell.

My pump has run for 4640 hours apparently, which translates to a lifetime average speed of the vehicle of about 26mph!

 

I'll upload the file shortly.

 

Here you go.

 

Thank you. It's strange that mine doesn't show anything. Starting to believe that the sensor is bad and at long term it burns the pump...

[Breezy_Pete]

Well mine showing Too Low doesn't seem too different to yours saying '0', and my system works fine?

Is your VCDS the full system? Your MB/column labels seem to have better descriptions than mine.

[Breezy_Pete]

Here are a pair of scatter plots of your log (top one) and mine this morning (bottom). Terminal 30 voltage on the x-axis, pump current on the y-axis.

 

Your data points are closer together in time, but your log is for less than half the duration, so although yours looks like it has more data points, there are roughly the same number, a few more in my plot, so must be lots on top of others. Your log has about 800 data points, mine 1200.

 

Your terminal 30 voltage is generally lower, your PAS pump is often using more current than mine. This may be completely to do with your journey/speed/number of turns but it does suggest your pump is having to work harder, and your alternator/battery combination are having more trouble satisfying the current demand. Any time the terminal 30 voltage is below about 13.8V, your battery is not being charged much at all. Was that log of any particular journey? e.g. your commute to work? Average speed?

 

[dm222]

It was in city, I will check tonight a differnent location.

[dm222]

Your chart is from the second or the first trip, and were the headlights on in the second?

I will post another tonight after work but I'm almost sure my voltage never goes much beyond 13,8V with headlights turned on... It stays at 13,77V and sometimes goes to 13,85V.

With headlights turned off it has more 0,2V, you can see at the beginning and at the end 14,01V.

Edited 11 August, 2015 by dm222

[Breezy_Pete]

Plot is the first trip.
Headlights weren't on for the second trip.

 

Plot for lunchtime run, all low-speed stuff round a business park, without headlights (about 300 data points):

[dm222]

Here it is Wino

https://drive.google.com/file/d/0B5pgma4HYX7dNG1KYncyb2hnYzRYaUZpY1FaSW02cFhTNjhZ/view

 

I added the engine speed, KM/H

 

What do you think?

 

PS: Headligts and radio were ON

Edited 11 August, 2015 by dm222

[dm222]

One stupid question.

 

If the engine rotates at 3000rpm and 2000rpm and the voltage is the same at both for example 14,0V, will it charge the battery more at 3000rpm than 2000rpm?

 

I usually drive at very low rpm to save fuel, but last three days I've been driving at higher rpm and the steering is lighter since yesterday.

Edited 11 August, 2015 by dm222

[Breezy_Pete]

Lots of useful data there. RPM is good because that correlates directly to what the alternator should be able to supply in Amps, Vehicle speed is good because it gives info about how much - or how little - steering assistance should be available, as you mentioned earlier.

 

I'll try to generate some plots tomorrow, but my main impression is that I don't think your alternator is completely healthy.  14.2 +/- 0.2 is the sort of voltage it should be producing across the battery terminals, with very little effect from adding loads like headlights.  Once the RPM is well above idle, there should be lots of spare generating capacity to offset loads like lights/PAS/cabin fan/radiator fans.  Your latest data (only briefly looked at now) seems to show that your alternator can only manage about 14.0V.

 

To answer the above question; at 3000 rpm engine speed, the alternator can supply a lot more current than at 2000 rpm engine speed, but if the voltage isn't being regulated to the correct level, that will limit the rate of charging that the battery can accept. The extra current availability can directly supply the PAS pump though, even if the battery isn't charging optimally.

[dm222]

Lots of useful data there. RPM is good because that correlates directly to what the alternator should be able to supply in Amps, Vehicle speed is good because it gives info about how much - or how little - steering assistance should be available, as you mentioned earlier.

 

I'll try to generate some plots tomorrow, but my main impression is that I don't think your alternator is completely healthy.  14.2 +/- 0.2 is the sort of voltage it should be producing across the battery terminals, with very little effect from adding loads like headlights.  Once the RPM is well above idle, there should be lots of spare generating capacity to offset loads like lights/PAS/cabin fan/radiator fans.  Your latest data (only briefly looked at now) seems to show that your alternator can only manage about 14.0V.

 

To answer the above question; at 3000 rpm engine speed, the alternator can supply a lot more current than at 2000 rpm engine speed, but if the voltage isn't being regulated to the correct level, that will limit the rate of charging that the battery can accept. The extra current availability can directly supply the PAS pump though, even if the battery isn't charging optimally.

 

I bought an multimeter to check the voltage directly at the battery, but realized after that need to buy a battery to the multimeter :S I didn't know it was necessary...

I will test it as soon as I have the battery

Edited 11 August, 2015 by dm222

[Breezy_Pete]

I think you'll find that VCDS terminal 30 voltage reports are exactly the same as what you measure across the battery. You could usefully measure the voltage right at the alternator output bolt though, with the negative meter probe on either battery negative, or a good clean metal bit of the engine; just to check that you are not losing any voltage in any wires or connections, but I think that would lead to more variable readings in VCDS.

 

It might be as simple as a bad contact between the voltage regulator and the points it connects to inside the alternator, but you'll have to take the alternator off to check that sort of thing. Bosch alternator is a bit easier to examine than Valeo version, I think. Not sure. See what yours is, and I may be able to help to show you what to check.

[dm222]

I think you'll find that VCDS terminal 30 voltage reports are exactly the same as what you measure across the battery. You could usefully measure the voltage right at the alternator output bolt though, with the negative meter probe on either battery negative, or a good clean metal bit of the engine; just to check that you are not losing any voltage in any wires or connections, but I think that would lead to more variable readings in VCDS.

 

It might be as simple as a bad contact between the voltage regulator and the points it connects to inside the alternator, but you'll have to take the alternator off to check that sort of thing. Bosch alternator is a bit easier to examine than Valeo version, I think. Not sure. See what yours is, and I may be able to help to show you what to check.

 

Question for 10000000000€  :p

 

Could a bad alternator cause damage to the steering pump?

Edited 11 August, 2015 by dm222

[Breezy_Pete]

I'm not sure, but low battery charge is a natural result of poor alternator performance, and that can adversely affect a lot of systems in these cars.

 

If you drive at low rpm in the city a lot, you need an alternator that is working at its best.

 

Here's the term 30 voltage versus PAS pump current plot for your last data:

 

 

Pump taking significant amounts of current during a lot of the sampled times, and voltage consistently below 14V.  The plot might be a little misleading, because it doesn't make clear how many data points are on top of each other, so could bias the appearance.

 

It would be really interesting to try logging the same journeys in another car with the same systems but an alternator that was 'better' to see a comparison plot.  I guess if you can mend or replace your alternator, you could do exactly that.

[dm222]

Also mine seems to be using more Amps, could that be a result of the low voltage?

 

 

P_(W) = I_(A) × V_(V)

 

A amp at low voltage is less than a amp at high voltage

Edited 12 August, 2015 by dm222

[Breezy_Pete]

It might be.  Without knowing how the pump power and control electronics work, I don't really know.  Because the system needs to react fast, and has feedback (specified and actual rpm) it could be that bigger than normal currents get supplied to the motor if it doesn't react fast enough, which might be the case if the voltage was low?

Do you have an external battery charger you could use, or a battery from another car that could be 'borrowed'?  If so, you could charge the battery overnight, then do another plot of one of the same journeys, and see what difference, if any, can be seen in the logs/plots.

 

Edit: thinking about it as a system, rather than the details; it takes a certain amount of power to work the hydraulics of the PAS. If that power is supplied at a lower voltage, the current will have to be higher to compensate. Higher currents mean higher losses, more heat, more problems, I imagine.

[dm222]

Very useful article:

 

http://ecmweb.com/design/highs-and-lows-motor-voltage

[dm222]

My voltages with a voltimeter:

 

13.85V idle lights turned off

12,70V car stopped

 

If I put the positive end at the alternator (outside the alternator in the metal) and the negative at the negative from the battery can I check what voltage is the alternator generating?

Edited 12 August, 2015 by dm222

[Breezy_Pete]

To measure the output voltage directly at the alternator, you need to lift off the plastic cover over the nut that holds the thick wire onto it, the terminal labelled B+, and put your positive meter probe on there.

 

Expect it to be the same as the reading at the battery post though, the two are connected by a thick, low-resistance wire.  Only if the connections are corroded/damaged/loose, or if there is a very big current flowing at the time, would you expect to see a different voltage there.

[dm222]

Today with the car parked at the same location measured the voltages again before going to work:

 

- voltage drop test from the alternator case to the negative from the battery 0,0V

- battery voltage 14,34V car idle

- battery voltage 12,59 car stopped

 

What is happening, any ideas?

Edited 13 August, 2015 by dm222