Diesel Power Down?

[Guest MartinSurfer]

It's a 5 year old 1.9TDi 110bhp with 40,000 on the clock. Recently noticed that it seems down on power, especially on gentle uphill gradients, it reacts like it's got 7 people in it even when I'm on my own.

 

I used to own the Seat Alh... 1.9TDi 90bhp and I'm convinced the Galaxy is now down to that level. Does anyone know if the Turbo's are likely to go off the boil? I think it's been like that for the last 3 or 4 tankfulls so am not suspecting the diesel quality. But then who knows?

 

Can the garages do a sensible test on this?

 

Grateful for any views.

[Guest vr6galaxy]

Most common cause of power loss on TDI's is Maf sensor failure! do a search on the topic and its symptoms and how to diagnose the problem

[Guest MATT]

i know somebody who had the same compliant, it turned out to be a problem with the Turbo Charger, not the actual mechanical bits, but the electronics involved with the turbo charger.

 

I think that VR6Galaxy may be right in thinking that the MAF (mass air flow sensor) has given up.

 

good luck,

 

matt

[Ivor_E_Tower]

... Turbo Charger, not the actual mechanical bits, but the electronics involved with the turbo charger.

Rumour has it that there are no electronics associated with the turbo :lol:

[Guest T120]

Good point Ivor but what controls the variable vane or the waste gate?

[Masked Marauder]

I don't know about the electronics of it but there are two solenoid valves connected to the engine vacuum system. One of them is connected directly to the turbo, another to the EGR valve.

 

When I took the head off mine, these pipes (rubber with cotton braided shielding) were rotten and had to be changed.

[Ivor_E_Tower]

IIRC wastegate is purely mechanical - spring rating etc. I think the linkage for the vane control is similarly "powered" too, buy may use a solenoid or stepper motor driven by ECU, based on inputs from throttle, road speed etc.

Anyone know the real answer? - and a while back, someone stated that the turbo doesn't have variable gemoetry anyway. I've not checked this out myself yet.

[Guest MATT]

... Turbo Charger, not the actual mechanical bits, but the electronics involved with the turbo charger.

Rumour has it that there are no electronics associated with the turbo :lol:

that

[Guest MATT]

...but there are two solenoid valves connected to the engine vacuum system. One of them is connected directly to the turbo, another to the EGR valve.

maybe what ever controls the solenoid has gone loopy.

[Guest vr6galaxy]

For Matt .........

 

http://static.howstuffworks.com/gif/turbo-plumbing.gif

[Guest MATT]

For Matt .........

 

http://static.howstuffworks.com/gif/turbo-plumbing.gif

 

HOW DO YOU MEAN 'FOR MATT...'

 

THATS WHAT I WAS EXPLAINING.

[Guest gritrash]

a while back, someone stated that the turbo doesn't have variable gemoetry anyway. I've not checked this out myself yet.

I think - but i stand to be corrected on this point - the latest generation PD TDi's have variable vane technology, but not older versions of the TDi engine.

[Guest MATT]

after reading my cars manual (reading manuals doesn

[seatkid]

i think that the 110ps has 'just a turbo'

and the 115 & 130 have 'variable vane turbos'

er...no...IIRC....

 

Only 110ps (Mk1 model only) = variable geometry turbo with no wastegate

All others = standard fixed geometry turbos with a vacuum operated wastegate

 

On the 110ps engine boost is controlled be a variable nozzle controlled by a vaccum pipe.

The variable turbocharger produces full boost pressure throughout the whole engine speed range.

 

This is done by the movement of the guide vanes which are located in front of the exhaust turbine, and the resulting change in the exhaust gas flow.

 

When the engine is accelerating the cross-section in front of the turbine wheel is continuously increased, and therefore the turbine speed and the amount of air needed by the engine are matched to the engine speed.

 

The boost pressure is approximately constant over the whole engine speed range.

 

The turbocharger is controlled by the powertrain control module (PCM).

 

The control pressure solenoid controls the vacuum at the vacuum canister for guide vane adjustment.

 

Boost pressure control is only performed by adjustment of the guide vanes.

 

 

Possible culprits for low power are

 

1. faulty MAF Sensor, (the ECU thinks Air flow is low and restricts fuelling)

2. faulty Boost sensor, giving low boost pressure and so low output

3. Sticky actuator on Turbo, restricting boost at high loads

4. leaks in the vacuum system (anywhere), can't move turbo actuator full travel

5. faulty Control Pressure Solenoid

6. Don't forget to check for a blocked air filter!

7. Leaks in the Boost pipework (joints) or intercooler (holes from road damage) usually given away by a loud hissssss

 

To check for turbo faults (and low boost due to vacuum faults) you need to T in a boost gauge and look at boost pressure under load. (IIRC 0.6 bar)

Edited February 4, 2005 by seatkid

[Guest Turbo]

I think we`re getting away from Martin`s problem here. As far as I know, 90 bhp mk1 Galaxy`s have a normal turbo whereas the 110 bhp engine comes with a variable geometry turbo. Isn`t it something to do with the shape of the veins that make it produce more pressure through the rev. range ? Normal turbo veins are pretty simple in shape while the variable geometry ones have shaped and curved veins.

But, I think poor Martin may find that he does have a MAF sensor fault. Has anyone successfully managed to clean one, bringing performance back to normal ? If not then I`m afraid, Martin you are possibly looking at a new MAF sensor.

[Guest gritrash]

i think that the 110ps has 'just a turbo'

and the 115 & 130 have 'variable vane turbos'

er...no...IIRC....

 

Only 110ps (Mk1 model only) = variable geometry turbo with no wastegate

All others = standard fixed geometry turbos with a vacuum operated wastegate

i have to agree with Matt, i think it is the other way round: the pd engines, that is 115 and 130 ps, have variable vane turbos, whilst older non-pd tdi engines have conventional non-variable turbos.

Sorry can't add anything further to original query!

[GSMGuy]

That's right mate - 115 & 130 have variable vanes...

 

 

 

Mike

[Guest MartinSurfer]

Thanks for all the suggestions everybody, I'm amazed and impressed by the response. Glad I joined. Will definitely research the MAF sensor and report back on how it goes.

 

Fyi I did 200 miles on the motorway this morning and whilst it didn't use more fuel than normal and ran very smoothly, it would not do more than 80 on the flat, and was a pig on the inclines. The second half of the pedal travel had no effect at all, at any speed. So that's definitely less power than my old 90bhp Alhambra; when I first switched to the Galaxy, I remember really eonjoying the significant extra oomph.

 

Presume I'll have to get a Haynes manual, or do you think I'll find equivalent tech help on a web site somewhere? (first seach didn't find much). I haven't had the need to buy a Haynes manual since about 4 cars ago, are they still the best guide do you think?

 

Cheers for now.

[Guest vr6galaxy]

Are you a pre or post face lift 2000? as the haynes only covers the MK1 upto 2000, although the majority of the running gear is the same the same, the internal and external trim is not, so it wont be a help to you on stripping down the interior but will help on jobs such as changing the brake pads etc, I would say it's worth it as little info is better than no info! and you alway have here to help if you get really stuck! :)

the other option is a TIS cd, you can pick these up on ebay for a few pound

[Guest MartinSurfer]

It's an early 2000, I got it new in March that year.

I've just been out and got the Haynes manual, covering up to July 2000 incl.

It says the only way to fault find is to have a properly equipped Ford garage plug it into their engine management diagnosis system, then replace parts as required.

However, I'm tempted to carefully dismantle the MAF first and see what I find (the wiring loom appears properly connected), it looks v easy to get at and extract. If I find nothing then submit and take it in.

Any better ideas?

What's a TIS CD?

 

Just one extra piece of info, a month or so ago I had to have the front windscreen replaced, I wonder what might have been knocked or squashed in the fitting process - it's a real big and heavy screen.....(?)

 

Bye for now.

[hitchhiker]

Just to add my $0.10 worth...

 

When i had my 2000W, 1.9dti gal serviced recently, the mechanic said the power was a bit down in the upper rev range and suspected the MAF sensor. I said i dont often go over 2500rpm ( :) ) and hadnt noticed the power loss except when trying to overtake lorries on hills (no chance). So i took a risk and got a new MAF from vag-components as recommened on this forum (cost

[seatkid]

That's right mate - 115 & 130 have variable vanes...

Just checking to see if you were paying attention :D

 

PD engines have VVT, so does 110ps TDi - the rest are fixed/wastegate types :)

[Guest MartinSurfer]

Question for hitchhiker - my situation sounds similar to yours.

 

I've just had the MAF out and everything looks clean and new, and obviously nothing on the MAF that can be dismantled or repaired.

 

I presume your faulty one looked pefectly ok when you removed it?

 

Am I right in thinking there's just one more check I can do before chancing the new part or the Ford garage, and that's trying driving without the MAF connected - if there's no change in performance then that increases the chances that it's the MAF that's faulty, yes? No chance of causing further damage by driving with it disconnected?

 

Have much appreciated all comments so far.

[seatkid]

Faulty MAFs look the same as good ones....some have reported that they fixed theirs by cleaning (using solvents), but I tried this and it didnt work for me.

 

Driving with a faulty MAF (or disconnected) doesnt damage anything, just restricts power output.

[Guest MartinSurfer]

I'll buy and fit a new MAF on Sat 12th and report back here how it goes.

Bye for now.