c8 automatic gearbox (al4) issues

[arronmc]

hi i have a 2005 c8 2.0 16v automatic that wont go i have changed the solenoids still no joy so i replaced the valve body and it still wont go , the symptoms are when you put it in park it wont lock the box ,if you start the car put it straight into drive and rev it to about 2k it will have a half hearted attempt at pulling away for about 2-3 seconds then nothing unless you turn off the engine and restart it then it will do the same fault codes being displayed are -p0706 p1167 and p1592 , i have a replacement working box but it doesnt have a torque convertor
any advice will be appreciated cheers arron

[CitroJim]

If it won't engage park then there's a mechanical issue inside the 'box, the selector cable is well out of adjustment or the gear position switch is out of adjustment. The fault P0706 may allude to that. The two other faults are to do with the engine so can be dismissed. The gear position switch - that tells the ECU what position the selector lever is in - is critical to correct 'box operation.

Have you checked the selector cable adjustment and does your gear indicator work normally?

Rather than try to interpret P faults you'd be far better off using a Citroen Lexia for diagnostics as that'll then give faults in rather more detail and in English.

You never change a 'box without having the torque converter refurbished so that's not an issue. Have yours done whilst the boxes are being swapped over if you find you need to do that.

This replacement box you have. Are you sure it's identical to your present one? If it is just a bit different in gear ratios or final drive then it ill not be happy and the ECU will throw faults...

[addo]

Was the valve body new?

[Mandrake]

According to this page:

http://www.bba-reman.com/content.aspx?c ... ault_codes" onclick="window.open(this.href);return false;

"P1167 Invalid test throttle not pressed (AL4 - Fault in pressure regulation - variation/recommendation)"

It appears to be a dual purpose code but it will be the fault in pressure regulation part that is relevant.

The other two codes I can't find a match for. As Jim suggests you really need to get this put on a Lexia as the above fault code plus your symptoms suggests that you have very low rail pressure. As well as confirming the fault codes the Lexia can measure the actual rail pressure on an AL4 in real time and I will almost guarentee that it is very low which means major problems.

Before you throw any more money at this gearbox I would suggest that you read the following thread which is my diagnosis of another AL4 with very similar no-drive problems:

http://www.frenchcarforum.co.uk/forum/v ... =3&t=41417" onclick="window.open(this.href);return false;

In that case the rail pressure started normally but dropped within a minute below the point at which the clutches will engage causing all drive to be lost.

If you've replaced the solenoids and the valve block and they're both in good condition and have been fitted properly, the most likely cause of low pressure is a blocked filter or faulty oil pump. (Jim ?)

Either way if you can put it on a Lexia you will get a real time readout of the rail pressure and this will give an idea of what is going on, however the bad news its its almost certainly going to be a full overhaul or a replacement gearbox.

[addo]

It's seriously hard to kill an AL4. What does get really nasty is bushing wear on the torque converter neck; they get massive vibrations in the 'box.

A good clue-in on the AL4 weaknesses is what Sonnax sell. An uprated accumulator kit for the VB, renewable bushings (some with reamer kits to make up for wear in light alloy castings) and of course the friction parts/hardparts.

[arronmc]

hi the valve body is from the second hand box which was removed from a running car (c5 2.0 16v)
the replacement box has a different code on it which i presume is to do with the gear ratios so thats a no go now , looking at the symptoms im leaning towards a blocked filter which i think will mean ill have to take the box out and get it reconditioned as c8 2.0 16v ones are like hens teeth .
thanks for the replies cheers arron

[CitroJim]

Aaron, if you're a competent engineer, and by the fact you have changed a valve block you obviously are, then it's not beyond you to overhaul the 'box yourself...

I've done several HP20s, the AL4's big sister, and here's some notes I wrote on the job to give you an idea of what's involved. The AL4 will be fairly similar.

I also have a copy of a rebuild manual for the AL4 which I could make available to you. Send me a PM if you want it...

In my experience, overhauling an autobox is actually easier than a manual 'box.

[addo]

Except that the main blights on an AL4 now, are physical wear. Hence my comments about bushing replacement. This is serious workshop stuff.

Line pressure is easily checked on Lexia; my suspicion about the poor behaviour would be wear in the mechanical accumulator in the valve body or accumulated muck right through it. 4711 trans fluid is very hard to flush out of fine gaps including inside solenoids, especially when it's got added silt from light wear to the soft metal parts.

[arronmc]

i thought that the valve body was at fault aswell but after replacing the borg warner valves to no avail i replaced the valve body with one from a good box which i in turn fitted the new valves to as a matter of course and the symptoms are still the same , there is some pressure there on start up as it will attempt to drive then it just gives up im going to replace the oil pump and filter plus any other parts that are needed aswell as getting the torque converter checked i will get back with the results of this as soon as i have got it done
atb arron

[Mandrake]

Arron,

Did the new valve block have different brand solenoids to the original ? Replacement parts solenoids for the AL4 are a different brand to the original and if fitted you MUST perform a firmware update of the ECU so that it knows how to operate the new solenoids correctly.

Its not stated in the service data what the symptoms of not updating the firmware are with the alternative replacement brand solenoids, but it is stated that the firmware update is imperative.

To update the firmware you need to use a Lexia. Where abouts are you located ? Check the Lexia sticky thread on the forum for the locations of forum members who have a Lexia. If you have one near you before pulling the box out it would be well worth checking both the rail pressure and also attempting to perform the firmware update in case you're trying to use new solenoids with old firmware. As far as I know its safe to use the new firmware with the old solenoid type if you do in fact still have the original brand fitted.

[addo]

That is correct, the upgrade is back-compatible.

I reiterate, the valve blocks are dodgy. They are the weak link. I have also known poorly solenoids to be supplied in replacement situations. Trust nothing except NEW unless you have the facilities to ultrasonically pulse clean all solenoids and precisely ream the mechanical accumulator for an oversized unit.

http://www.sonnax.com/product-lines/tra ... line=trans" onclick="window.open(this.href);return false;

[addo]

A side note.

The park pawl is 100% mechanical and quite simple (it's external to the geartrain), so if this is not engaging, you have possibly not aligned the shuttle valve correctly upon refitting the valve body.

[arronmc]

hi it had the borg warner valves in to start with i looked at the lexia map only problem is the car wont move at all
atb arron

[addo]

With the valve block off, can you manually operate the parking pawl?

[arronmc]

park is sorted now it was gear lever alighnment all codes except p1167 are now cleared , i have removed the oil pump and filter from the good box (actualy realy straight forward to do ), i think i can rule out the torque converter as being at fault as im certain this would bring up speed variation faults not a pressure one . so next step i think is i will swap over the pump and filter and see if that sorts it .
i will try and post a step by step picture account of the pump being swaped incase this is of any help to any other members thanks for all the help every one
atb arron