Hi,

 

I've read every power steering thread on the Fabia I forum, but none of them exactly fits my situation, so I've decided to throw another thread into the PAS fire...

 

Fabia Classic 2002. PAS works, but it's far too weak. Turning the wheel requires a lot of strength, but I've concluded it's still working since driving with pump disconnected is much worse still.

 

Conclusions this far:

No power steering warning light and no fault codes.

New 62Ah battery fully charged.

Fuses on top of the battery is fine. Fuse 7 in the car is fine.

Alternator charging wire is fine, since the battery light comes on with the ignition and then disappears.

Battery is getting 14,4v from the alternator with engine running.

Fluid level is good.

Angle sensor is of the new model with a metal lid. Also it gives live data in VCDS so I've ruled this out.

Been cleaning every earth return I could find, also the ones below the battery.

 

VCDS-Lite shows the following info:

And "measuring blocks" with engine running while turning the wheel:

 

Apparently VCDS sees the pump as healthy.

 

I disconnected the power plug to the pump and measured voltage with engine running, and it's getting about 14,3volt. I also measured about 12,3volt with engine switched off. Is this normal?

 

Could this be signs of a pump on the verge of giving up? It stopped working as normal a while back when my old alternator started acting up. It outputted far too high voltage. Measured around 17-18volts over the battery terminals with engine doing 2500RPM. Changed to a new alternator doing a healthy 14,4v no matter the engine RPM, but the PAS remained broken.

 

Any ideas is welcome!

12.3V is rather low for a brand new battery.

 

7A current draw from the PAS pump is very low, it suggests the pump is in low power mode.

 

Have you done an Autoscan and cleared all the codes in all the modules?

Can you log measuring blocks 1,2 & 4 of the steering assist module while you're driving for ten minutes or so?

sepulchrave: Unfortunately the auto scan fails on my unregistered VCDS-lite, since the 2nd or 3rd module scanned requires a registered version. I have gone through all the modules manually though, but there's a slight possibility I may have missed something. I've not yet reached the point where I'm just gonna pay the $99.

 

Wino: Certainly. Just logged a ride around town.

LOG-44-001-002-004.CSV

 

Also just noticed on this test drive that when riding on gravel (which I usually don't), the steering is feeling much lighter. That's expected, but it's as close to normal as it has been for a long time. As soon as you enter "firm ground" again you can feel the PAS starts to struggle, and also turning the wheel feels a bit jerky. As though it's trying, but constantly runs out of juice since it's too much for it to handle.

 

Thanks.

Are you certain that the PAS fluid level is correct and that there are no leaks?

sepulchrave: yeah, I've checked the fluid level multiple times in the last couple of months, and it has been constant at the same level... it's covering the whole little indent on the meter on inside of the lid.

Very strange, the pump must be failing, there is nothing else it can be.

Very strange, the pump must be failing, there is nothing else it can be.

what about if the steering weight's been adjusted in VCDS? 1-7 I believe, 1 being lightest IIRC.

what about if the steering weight's been adjusted in VCDS? 1-7 I believe, 1 being lightest IIRC.

 

Look at the coding; 00110 in the first picture, I've mucked about with the codings and all of them are too light, no this is something else.

This is the scatter plot of terminal 30 voltage against pump current for your logged journey:

 

 

Your battery and charging system seem to me to be good.  The pump is never causing the battery voltage to dip too much.

 

Looking at your turn rate column versus pump current though, it looks a bit strange.  It's too late and I've had a little too much nice red wine to be sure, but I don't think my pump current ever drops below 3A in any log I've taken. Yours seems to drop below that, right to zero, quite often. Also, look at around row 283 onwards of your log; there's a time there where your turn rate starts registering quite big numbers, but your pump current is actually going down? This may be because your road speed is high, meaning not so much assistance is specified, but I find that strange/illogical.

The maximum pump current does seem low also, compared with all the logs I've seen.  I can't think of a simple explanation for these data just now.  Maybe tomorrow will bring more clarity.

 

 

So, now it's morning and I've had another look at your data, and my last log taken on Friday in my Polo.  My pump current does drop below 3A sometimes, so I think that 'abnormality' was a figment of my imagination.

Also, in my last scatter plot, there are only two points of higher current than yours (turning sharp right into my parking space at work, low speed, low revs; Time stamp 613 is the 37A one, the one above it that I've managed to crop out is the 33A one with a turn rate of 382), otherwise the plots look pretty similar: 

 

 

The pump current (I Pump, above in two columns) doesn't always correlate immediately with turn rate, and sometimes differs dramatically between samples (TS, above in 3 columns) only 1/3 second apart.  So the absence of any big numbers in your plot may just be that the sampling missed the highest peaks.

 

Your charging voltage is a little lower, but not enough to make a big difference to your power steering, I don't think.

 

So I'm not convinced there is anything wrong with your pump.  You even have "Correct" in your sensor reference voltage column, which is interesting. I was half convinced that voltage was only relevant to Koyo sensors, as both cars I have access to say Too Low there, and nothing seems wrong with the PAS on either. :think: