Intermittent Loss Of Power

[jim prong]

I did raise this on another thread, but I hope someone can throw a little light on the matter. I've sorted a problemI had with the VNT, and the actuator now moves freely. It did run fine for a couple of weeks but now it goes into a really low power mode. I mean really low, ten to fifteen mph. If I stop the engine and restart it again, the power usually returns to normal, but if I take my foot off the accelerator, it goes back into low power again. When the power is normal, I can hear the turbo spool up which I don't remember hearing before. I suppose it could be air escaping from the system, but as I say it only effects the power after I've lifted, and then press once more. 

 

I get two fault codes, P1556 Charge Pressure Contr. Negative Deviation

 

and P1570 Engine Start Blocked by Immobiliser ( makes no sense because it starts and runs).

 

Could it be the MAP sensor,? Does that control the boost level? My son has a Sharan, so I'm going to do a test with his MAP. All hoses look OK, but I'm not one hundred percent sure. The fact that its intermittent is pointing me towards a sensor of valve solenoid.

 

Any ideas please? 

[chrispb123456]

You may do better by getting yourself a vagcom/VCDS cable and collect some live data, should give you more of a clue to what's going on.

[jim prong]

You may do better by getting yourself a vagcom/VCDS cable and collect some live data, should give you more of a clue to what's going on.

One of the cheap ones off eBay?

[SilverBeast]

This will do the job.

[jim prong]

This will do the job.

OK, thanks.

 

Just spoken to my son and he's got one for his Sharan. 

 

Is there a tutorial anywhere on how to use the VCDS Lite? 

[jim prong]

Re my post above, I've found the guide where I should have looked in the first place, the Ross-Tech site. Having some problems connecting but I've not done any trouble shooting yet.

[motly]

I too am plagued with odd 'limp mode' problems. The turbo was replaced and all seemed OK for about 18 months then 3 months ago had to be AA'd back from Cornwall. Since then and  about

[chrispb123456]

You may need to clean your throttle position sensor, remove throttle pedal unit from car remove three or four screws that hold the cover on, remove cover and clean rubbing track with switch  cleaner leave to air dry then refit.

[SilverBeast]

I believe the accelerator is electronic and contains two potentiometers that need to agree for the ecu to believe the signals from it.  It is possible that they are not agreeing and the ECU goes into a safe mode and keeps the engine at a constant speed.  There are other threads about this if you search.  Try this one. Search for throttle position sensor

[motly]

Thanks 

chrispb123456 and SilverBeast . I might have a look at this or get it looked at. Are there pictures anywhere freely available and is full access to it within the car?

[chrispb123456]

Have a look here

 

http://www.forum.fordmpv.com/smf2/ford-galaxy-reference-library/galaxy-accelerator-pedal-removal-and-cleaning-(vcds-fault-code-00777-18047)/msg4976/#msg4976

[motly]

Cheers Chris..

[motly]

Just to keep you up to date. I removed the accelerator unit and took it apart. It looked perfect bu i cleaned the circuit potentiometer tracks and slide contacts with iso alcohol, re assembled and re installed the unit. So far I have not had any problems and seem to be able to get the revs up higher than I have before. I am 'heavily' into electronics and it would have been fairly easy to bench check the unit by applying a low voltage to the pots and looking at the wiper voltages on a dual trace oscilloscope. Never mind, I needed to get it out and back in before the heavens opened and that has not been easy recently. Another observation. If the unit is re assembled fractionally off from its original position, it may well be that the wipers will be moving up and down on a fresh, unused part of the printed resistor track. I might get a cheapy from fleabay and play. Thanks for your help. I will keep you posted.

[SilverBeast]

Glad you are sorted. I believe you can monitor the two outputs from the throttle position sensor with VCDS-LITE/VAG-COM

[motly]

I thought the best you could do with the lite version is read fault codes. Will have to look into that. Went 40 miles on the motorway before the fault became evident again. The removal and subsequent clean and replacement of the accelerator 'lump' does not seem to be a complete cure. I still have problems with hesitation when the pedal is depressed. Sometimes the car will not go over 60 mph in a situation when it could easily do 80. However, the fault does seem different from before. I have purchased a second hand unit from Ebay and will thoroughly check it before installing and have another go. 

[Trislander]

The eBay item, does that cover ford galaxy? As in its description it doesn't mention it

[motly]

Ford Galaxy Mk2 2001->2006 Throttle Accelerator Pedal 7M4 721 603 D

Is quoted. I'll let you know what I actually get.

[SilverBeast]

 

The eBay item, does that cover ford galaxy? As in its description it doesn't mention it

 

Assuming you mean the VCDS-LITE/VAG-COM lead.  Yes it does cover Ford Galaxy as this was built by VW. It will work for TDI and possibly V6 engines but not 2.0/2.3 Ford petrol engines.

[motly]

Well, that didn't fix it. Just when you get to thinking you cracked it...Fitted the replacement accelerator and gubbins but still have the same problems. Driven nice and sedately it seems a little sluggish but picks up and runs OK. Get on a decent road and with the revs at about 2500 and held there (55mph or abouts) for a couple of minutes, if you try to go any faster, the revs will not increase. If you slow down a bit and change gear things only get worse and the maximum speed drops further. Reducing the revs slightly by backing off the accelerator at least allows you to continue at a reasonable speed. Push it, and it goes down eventually to an embarrassing 20mph. Turn off, remove key, wait 30 seconds, and restart. Things are back to normal. This time using VagCom fault code..

17964 Charge Pressure Control: Negative deviation P1556 - 35-00- -

 

I am getting seriously peed off. As  I stated before, I don't mind spending the money and really like the car but not getting anywhere despite replacing several parts hoses etc and about

[chrispb123456]

So negative deviation is lack of boost pressure, this may be something as simple as a leak between the turbo outlet and the intake manifold, can you hear any hissing whooshing noises?

 

The valve (N75) that controls the vacuum that operates the turbo actuator and associated pipework hidden behind the heatshield at the back of the engine

 

Then we come back to the turbo itself sticking vanes? have you tried operating the actuator by hand, does it move it's full travel without sticking (bearing in mind the strong spring inside the actuator and restricted location 

[motly]

Hi Chris,

I am partially deaf and it's high frequency deafness.. ie I can't hear the letters  F S T etc. That means I can just about hear the air leaking from the tyre valve when using a pump. I am also 66 and not really able to get under the car for any length of time. Don't get me wrong, I'd love to and have done engine and gearbox replacements in my time. I guess I am really looking for something that I can easily do or someone who can come and do it for me. I am not looking for a freebie just a guaranteed fix even if it does cost a fair bit.

 Thanks for your help.

[chrispb123456]

whereabouts in Kent are you?

[motly]

Tatsfield. Up the hill from Westerham.