Advice From Techies If Possible...long

[Guest GT-Four]

hi

 

my sister has a 2001 1.9 tdi galaxy and is having problems

 

after driving it tonight i would have to agree very sluggish and no feeling of a turbocharger coming on boost it has been into ford numerous times but they are nigh on useless :-(

 

it has the obligatory water ingress that seems all to common (beleive pollen filter can be a culprit also blocked drains) again ford havnt been able to sort this either so with the info i have from here hopefully i can put that one to bed for her

 

but more importantly the performance is well down on what i would expect

 

the ford guy told her that the turbo is only producing 1bar of pressure....and should be producing 2!!!!! now excuse my ignorance but im doubting very much that ford push 28psi into these engines and they still hold together.

 

they are trying to steer her towards a new turbo

 

my questions are

 

is there any form of ecu control over turbo pressure?(as there is in my toyota)

 

they say that they have done diagnostics on the MAF sensor and have also changed a solenoid of some description...sorry i got this secondhand so i dont know which solenoid they would change for low turbo pressure?

 

also with the engine undertrays off how accessable is the turbocharger

as i would like to inspect the intake hoses and compressor wheel.

 

if anyone could help i would be most gratefull

 

TIA

john

[Topbloke]

the tdi manifold/ plennum chamber does get very gummed up try a search this has been covered, they are also prone to maf sensor faults again try searching the garage may have checked the codes but as you say they aint that clued up easy test for the maf sensor is disconect and see if there is any noticeable difference, worth checking the air filter/air trunking for obstructions,and also check to see if any pipes are off and the old chesnut the brake light switch/bulbs to make sure that the bulbs are not on all the time

[Ivor_E_Tower]

How did they check the turbo boost and get a figure of 1 bar boost pressure? If all else fails, remember that this is a VW engine and you may have better luck from a VW dealer (or independent specialist). IIRC the solenoid should operate the deflector plate (for the variable geometry turbo) but the boost iteslf should be limited by a preset spring value on the wastegate. I stand to be corrected and will bow to the greater knowledge of any TDI specialists out there .......

[Masked Marauder]

I think the maximum boost is about 21psi dropping to 15psi, but I could be (and often am) wrong.

 

So thats a little over 1 bar at normal boost going upto about 1 1/2 bar at peak spike.

[Guest GT-Four]

the old chesnut the brake light switch/bulbs to make sure that the bulbs are not on all the time

im confused by how this would effect the turbo???

[Ivor_E_Tower]

Drive-by-wire; if the computer thinks you are braking because of a faulty brake light switch, it limits the fuel supply (and hence power that the engine can produce).

[GSMGuy]

The turbo boost does reach 2bar plus... Taken from VAG-COM site...

 

http://img217.echo.cx/img217/3705/screenhunter0011hx.jpg

 

I presume the 2.1 for a short while is an "overboost" to help acceleration

 

 

Mike

[rick-curl]

John,

 

I had the same problem with my car, a Sharan, that the VW main dealer failed to diagnose at two attempts. No code in the VAG-COM diagnostics.

 

A local, competent, independent traced it to the Air-mass flow meter, which swapped restored the performance.

 

Reading the VW techi stuff, the MAF's measure the fresh air to the engine and calculates the exhaust gas recirculation rate and the permissible injection quantity.

 

If the unit fails, the ECU defaults to a fixed air mass value and restricts the throttle range. Remember that the throttle is fly-by-wire so whilst you may have your foot to the board. the signal to the injector pump will be something a lot less and hence the performance.

 

The down side is that the MAF is not cheep and not a part you want to fault by swapping out.

 

Hope this helps

[Guest Sharan Driver]

Just so there is no confusion;

 

Note that the pressure quoted by VAG-com is mBar Absolute. 1 Bar Absolute is around atmospheric pressure, ie no turbo boast.

 

2 Bar Absolute is an increase of 1Bar over nominal atmospheric pressure ie around 15psi.

 

Also check for leaks in the small pipes to and from the Turbo Control Value ( forget the proper name) . Mind had rubbed on some wiring and had worn a hole in it

 

 

 

Chris

[seatkid]

Dear GT-Four,

 

Please ignore Dealers advice, it is almost always wrong.

The solenoid they changed was probably the TCS Turbo control solenoid, which regulates the vacuum to wastegate or variable vane actuator depending on the type of turbo fitted.

 

There is nothing wrong with your turbo.

 

Your car has classic MAF failure symptom.

 

Change the MAF sensor, exchange units are available at dealers for around

[Guest GT-Four]

lol

 

i did think 2bar over atmospheric was a bit high for a diesel in fact even 1 bar seems high!!

 

i was always under the impression that TDs always ran relatively low boost around 5-6 psi max

 

seems the MAF is suspect number one from the replies i have had so far

[Guest GT-Four]

oh and thank you all very much for the replies so far :-)

[Guest GT-Four]

 

 

the ford guy told her that the turbo is only producing 1bar of pressure....and should be producing 2!!!!!

 

 

mmmm wonder if the 1bar is just atmospheric pressure and the turbo isnt boosting at all.

does feel like a NA diesel when driven

[Dave-G]

GT-Four...just pull off the plug of your maf sensor and go for a drive...if it runs better- then the maf is due for reconditioning

 

I say reconditioning because I suspect thats whats being done to the exchange ones...I want one to try myself but need to wait untill my own becomes a problem before I can prove it

 

someone on here assured me they would send me their duff one but I guess he forgot once we put him right...It's alledgedly sitting there all packed up waiting zzzzzzzzzzzzzzzz

 

If anyone else has a duffer, perhaps they could send it to me ?

[Guest neil_wiles]

Dave

 

The MAF sensor I believe if the Bosch unit as fitted to numerous cars, if it is it is encapsulated and the "reconditioned" ones are just replacements from Bosch.

 

I stripped one down and the resistive coil is normally pitted beyond use when they fail, reconditioning would be to replace the whole sensor head whilst flow soldering it back to the transmitter pcb, then re-encapsulating it.

 

I tried cleaning and brushing but all I managed was to reduce the signal levels even further from the specification.

 

If you do find a way to refurbish them I am sure many of us would be over the moon.

 

If you dont get a duff one soon I will try and obtain one I will let you know if I do.

[seatkid]

Dave-G determined to prove he can fetch things back from the dead.....explains the pic he posted sometime back :P ....do you only come out at night Dave?

 

I tried cleaning one but to no avail. What Neil describes is very plausible - the hot film errodes (oxidation). The integrated electronics recalibrates (on power cycling) until the point it can recal no more.

 

The exchange unit scheme is merely as a result of either VAG/customer complaints, warranty problems, or because they only cost

[Dave-G]

:P Thanks ...both :P

 

I'll look forwards to that neil, thanking you in advance

 

I could easily be barking up the wrong tree...or plain barking!...but I ve got it into me ead son...

[Guest GT-Four]

thanks so much people

 

disconncted the MAF plug and it was a different animal definatly pulled and drove better....soo a new MAF required

 

And to think a ford dealer wanted to fit a new turbo!!!!!!!!

 

Does the MAF fault not show up on there diagnostic equipment?

 

do they not check resistances on the MAF itself?

 

anyone on here a ford technician and can answer those Qs

 

regards and thanks

john

[seatkid]

I think the problem with diagnosing Maf faults is that all MAF's drift with age but so long as there is a varying output (in the allowable range) the ECU wont fault it but assumes the air flow is blocked by a dirty air filter.

 

Remember the job of the MAF sensor in a diesel is to ensure Euro compliance, i.e. that it is not overfuelled and produces smoke etc.

 

There are possibly (as I speak) a large percentage of diesel cars (and not just VAG cars) on the road with reduced performance due to a half cooked MAF sensor. A lot of people don't notice it as it initially only affects top end performance and it then deteriorates (reducing maximum power) gradually.

 

In this case the driving sytle adapts to the ECU :unsure: .....

[Guest GT-Four]

Thanks all

 

fitted new MAF obtained from a guy on ebay it pulls and drives fantasticly now

 

dave-g your welcome to have the old sensor if you send me a pre paid jiffy bag i will pop it in the post for you to play with.

 

just one thing

 

between the maf sensor and the airfilter housing should there be a rubber sealing ring??

 

if so it isnt present so i would need to obtain one

 

again many thanks all who have helped

 

cheers john

[Guest MATT]

i believe that there should be.

 

MATT

[Grandad]

Hi Guys,

 

I've been reading your correspondence with interest.

 

I disconnected the MAF on my VR6 a few months ago but there was no difference in the sluggish performance - especially up hills. Does this mean I need a new MAF?

Incidentally, the gal has just passed it's MOT with the MAF disconnected.

 

thanks

 

Grandad

[seatkid]

Probably

[Dave-G]

B) GT-Four :(

 

:P I'd about given up on that thanks mate. :D

 

If this is the o-ring you refer to I'll send it in a jiffy bag that contains a self addressed one if the offer still stands?

[Guest GT-Four]

hi dave

thanks for the picture

 

its actually at the connection of the duct at the airfilter

 

the maf i got was the sensor + the duct

 

http://img.photobucket.com/albums/v627/gt4play2000/maf.jpg

 

shameless picture for the hell of it...my gt4 celica :-)

 

http://img.photobucket.com/albums/v627/gt4play2000/castrol.jpg