Diesel 98 Galaxy. Poor Fuel Economy And Soot

[mazzo]

Hi

 

I have been reading as many threads on poor performance as I can, but I'm still not confident that I'm on the right track.

 

My 98 TDi normally runs beautifully, but recently a number of things have started happening. I'll give them in order:

 

1. At MOT, it just scraped through emissions. They said "you need a service" and I told them it had just had one!

 

2. At night as I'm driving and I pull away from lights or accelerate (not madly mind you) I can see lots of smoke in my rear view in the beams from the car behind. I also notice soot if my wife drives off (with me watching out of the car)

 

3. I used to get about 42 to the gallon consistently, but now it's slipping into the late 30's.

 

4. Power seems OK - but I'm not a hacker and am used to small engined cars (apart from my last Galaxy which was a V6 and like a rocket!!)

 

I seem to think it's the MAF or injectors? I haven't disconnected the MAF because I've read a lots of posts that seem to contradict the outcome of doing so.

 

Any suggestions, tips, checks etc would be very helpful.

 

Thanks (and seasons greetings :rolleyes: )

[Beyond Help?]

Unplug the electriacal connector to the MAF, drive the car, if it is better or the same the MAF has had it.

 

I take it you have no dashboard engine warning lights on? Like the glowplug light flashing?

[mazzo]

Thanks - I will do that today and report back.

 

And yes, I have the glow plug light intermittently coming on - which I think is the brake pedal switch, however the performance is poor whether it is on or off. It doesn't always come on, it tends to be when cruising on the motorway or leaving the car idling for longer periods of time.

[Beyond Help?]

OK, well check the MAF and if that is not the problem look for splits in the vacuum hoses to and from the solenoids, the vacuum pipe to the turbo and the vacuum pipe to the EGR. Also check the plastic hose from the vacuum pump on the front of the engine has not chaffed through, although that would effect the brakes too so it is unlikely the problem. Edited December 28, 2007 by Beyond Help?

[mazzo]

Will do. It's piddling down here today, so hopefully do that tomorrow (wife permitting!)

 

Thanks - will report back when I have.

[Bigjeeze]

Something else you can do is to change the oil & filter and the air filter. When you next take it for an MOT remember to take it for a run and blow the crap out of it right before the test - it needs to be running at normal temp for the test. I would still check the MAF as this is also a likley cause. The filters etc are no extra cost because you have to do them anyway at some point.

[mrchipz]

How do you drive the old Gal?

These engines where designed to be thrashed up and down autobahns.

They don't like being driven lightly for too long.

There is a chance it could be being suffocated.

You mention smoke when accelarating.

When theres smoke, theres usually not enough air to burn the fuel correctly (There goes your mpgs as well).

Maybe the air intake is getting clogged.

Take the thick air pipe off the egr (the egr valve is bolted to the intake manifold) and stick your finger in hole and gently feel around for soot build up. Have a rag handy!

If you have a large build up it will be suffocating your engine. Your intake will need removing and cleaning, manifold and egr.

I try to redline my tdi at least once a trip to keep the air flowing. Even with my egr disabled.

 

This might not be the cause of your problems but it is easy and free to check.

If the engine can breathe ok then it could be injectors or injector timing. Try and get hold of someone with vag com software for this one.

 

Hope this helps.

Edited December 30, 2007 by mrchipz

[mazzo]

Thanks. Yes all of this helps.

 

Today I disconnected the MAF. Boy what a difference. No acceleration at all. Once reconnected, it was fine again. So I guess the MAF is not the culprit. I will have a look at the filters and egr.

 

It had the air filter changed a year ago and a new fuel filter, oil filter and oil change 3 months ago.

 

I have just filled up this afternoon and got 39mpg. It has been much better than this in the past.

 

I haven't checked the hoses yet, but will - at the same time as the egr.

 

As for driving, I mainly use it for long motorway journeys and occasional driving the family into town. In October I drove it to the south of France and back - and it was as good as gold. Fully loaded we were doing a constant 80 - 85mph and got about 45mpg.

 

Once again, this is all good advice. Thank you! :rolleyes:

[mrchipz]

Fully loaded we were doing a constant 80 - 85mph and got about 45mpg

 

Was this via the trip computer or your own calculations?

 

With mine at 80-85mph and no one else in I get about 35mpg. I've tested my trip computer and its about bang on.

 

If yours is correct then there might be something a miss with mine.

[mazzo]

No, that was by my calculations as I don't have the trip computer. What I do is fill the tank to the top every time and just work it out from the trip mileometer.

 

What I have noticed though is that the speedo and consequently the mileometer under-read. Speedo is more or less OK up to about 40, then it starts dropping by about 5mph so that at 70 on the clock I'm actually only doing 65. This is according to my sat nav with 12ft or less accuracy - which means its speed calculations are pretty good. Mileage is only a bit out, but over 100 miles is usually about 5 miles wrong.

[mazzo]

Right. Can't visibly see any problems with the hoses. The egr is reasonably clean, as is the air filter. But there are some newer developments!!!!!!

 

When accelerating in 3rd, 4th or 5th (not the others because the car is not having as much load in 1st and 2nd), at about 2000 - 3500 revs, the car accelerates but you can feel it being inconsistent - almost hesitant. It pulls fine then hangs back a bit, then pulls again, drops off, etc etc. Perhaps this is the start of the MAF going???

 

The other thing that I noticed at the weekend - and really a lot this morning, was the cloud of blue smoke as I started the engine from cold. Doesn't do it when it is warm, but on a cold start there seems to be loads of blue smoke. This morning the wind was blowing from behind the car and it blew the smoke all around the car and off across the garden. Lots of it!

[mrchipz]

According to Diesel Bobs website http://www.dieselbob.co.uk/tips.shtml

 

BLUE SMOKE from exhaust - Causes: Engine is burning engine oil, injection timing is incorrectly set.

 

or even worse under common faults

 

VW TDI ENGINES - drastic power loss, causes: injection pump internal collapse or air flow meter fault.

 

Lets hope for your sake its only the air flow meter.

 

Keeping my fingers crossed for you.

[mazzo]

Oh dear, that makes grim reading!

 

I hope it is the MAF too. Is there a way to get it checked out before I splash out, possibly needlessly, on a new one?

[mrchipz]

I would suggest getting the car hooked up to VAG-COM and see what that shows up. Do a search and see if you can find somebody near you.

Your quite welcome to use mine if you live near Grantham.

[gregers]

mazzo whereabouts in the south east are you?

[mazzo]

Thanks that's kind. I'm actually in Berkshire. I guess the VW or Ford dealer will be able to do it. I used to know a local guy some years ago who specialised in VW's and had the software, however he's moved!

[mrchipz]

ooops missed that South East bit!!!! lol.

[stevie m]

I disconnect my maf and ran the car. Performance was down of course but the hesitancy went. It was holding back then going before. Guess what i had just fitted a new FAULTY maf. Fitted new one and hey presto working fine. :lol: . Got a refund off the old one.

[mrchipz]

Glad you got it sorted!

[mazzo]

That wasn't me who got it sorted, but it is interesting. Now you mention it, although the performance was down when I disconnected the MAf, it was consistently down.

 

It's also interesting that yours was better with the MAF connected, yet it was still faulty. That sounds pretty close to what I'm experiencing.

 

Still I intend to get it diagnosed if I can first.

[stevie m]

Mazzo i have a code reader here and i should mention that my maf NEVER showed as being faulty on it although it was. It was as if it worked now and again. It left me with no option but to disconnect it. I did so for a couple of days. YES i actually put up with the performance reduction for more than one day. BUT it told me it was faulty, so it was worth while.

[mazzo]

That's interesting - and it told you it didn't work because although the performance was useless, it was consistently useless?

 

When I disconnected mine I couldn't tell much other than I was about to be hit by a bus when I pulled out of a road! Perhaps the extreme excitement of that blurred my senses somewhat! I think I'll have another go.

[stevie m]

That's interesting - and it told you it didn't work because although the performance was useless, it was consistently useless?

 

When I disconnected mine I couldn't tell much other than I was about to be hit by a bus when I pulled out of a road! Perhaps the extreme excitement of that blurred my senses somewhat! I think I'll have another go.

 

Hi again. The car was consistantly poor. The holding back dissapeared. The idling problem i developed went too. If you need a code reader and don't want to pay loads i will give you a link.

[stevie m]

Here :lol:

[mazzo]

Thanks!