807 Intermittent Power steering Problem

[Jo1]

We are having an intermittent power steering problem with our 2009 Peugeot 807 and we can't find the fault. The steering becomes very stiff with the first drive in the morning but only when the speed goes above 20-30mph. You have to oversteer the car when cornering to overcome the resistance. After doing this a few times the power steering seems to correct itself and is usually ok for the rest of the day but the problem returns the following morning. We have replaced both the steering rack and pump with a reconditioned rack and pump but it didn't solve the problem. We have also checked out all mechanical joints and everything is fine. The car doesn't show any faults when put under diagnostic testing. The problem seems to be worse on cold mornings. I would really appreciate any help or suggestions with this problem.

[wheeler]

Is it an electrical or mechanical pump on this model ? does it have the correct type of fluid in it ?

[Jo1]

Thanks for your reply. The power steering is an electric hydraulic power steering system. I'm not sure about the type of fluid used but it was got in a Citroen garage for electric power steering systems.

[spider]

You've checked the usual suspects for this, the only thing I can immediately think of is the speed sensor as it is speed sensitive.

[Jo1]

The steering seems to free up if you brake hard while cornering - would that also be connected to the speed control sensor? Have you any idea why it might be ok for the remainder of the day after the first drive or why it might be effected by cold weather?

[wheeler]

This is a strange one...
There wont be a separate speed sensor on the car, it will all be done through the ABS system so assuming the speedo is working as it should I would probably rule that out. You could try checking live data from the wheel speed sensors to see if they are all reading correctly. Are there any fault codes in the ABS/ESP system ? Are all the tyre sizes the same & does the ABS ECU have the correct tyre sizes programed ?
Can you just confirm, are you saying on first start up in the morning the steering works as it should straight away then once you reach 20-30 MPH it then starts to play up ?

[spider]

I do not have any specifics unfortunately. I would suggest 'on diag' (with an assistant as you can't do this safely on your own!) , compare the road speed on 'diag' with the vehicles actual speed. This will determine what the ECU thinks the speed is.

Don't rely on the speedometer working correctly for this, its important to see what the ECU thinks the vehicle speed is really. If this is miles out (no pun intended) then it could be a problem with that or an ABS sensor, I'm not sure where it picks the speed from, there might actually be a pickup in the housing in the transmission even though its probably not used for the speedometer as such.

[Jo1]

Many thanks for your comments. There are no faults coming up for the ABS/ESP system. I will discuss the speed sensor test with our mechanic tomorrow. The steering problem really only becomes noticeable above 20-30 MPH (it might not feel absolutely perfect below 20MPH but its not noticeable). It could be a coincidence but it wasn't cold this morning and the steering was fine. We're starting to question if the oil has somehow become contaminated and is effected by the temperature. We're going to try flushing out the whole system tomorrow and replace the oil with Fluide DA - hopefully that will work....

[spider]

I cannot think of any other cause that could be 'speed related' unfortunately.

A flush out won't do any harm (apart from to finances)

Although its not the same the very early 406 2.1TD and 3.0V6 (certainly the 2.1 at least) P and a few R plates had a speed sensitive system too, this was uber light at standstill but they changed this and later ones did not have the same lightness (typically later R plates) , the problem on those was usually the control box from what I can recall rather than the rack itself.

If your system was totally 'heavy' (powered but not enough) then the pump would be a suspect as with the 406 the 'ultra light' ones had a different higher pressure pump and I saw quite a few taxi's where they said they'd lost this extra lightness typically after fitting a 'used' pump from something else.

I'm not sure if this info is actually any help or hindrance at all but I wanted to post it as I'm about fresh out of other PAS related thoughts for you...

[p3gasso]

Did you find solution? I have same problem on Ulysse 2008, 100kW