according to this link id need a specialised tool to remove security screws so maybe i wasnt being such a dur :-)

Those screws hold the MAF itself (little stick shaped thing) into the MAF housing (the plastic cylinder in the air pipework), you don't need to remove those at all, just unplug the multiplug from the end of the MAF. If the MAF is the same type as the 1.8T (which I'm pretty sure it is) then you do have to depress that lug and wiggle the plug a bit to get it off. Don't get too heavy handed with it though as I managed to snap the clip on mine taking it off :(

Those screws hold the MAF itself (little stick shaped thing) into the MAF housing (the plastic cylinder in the air pipework), you don't need to remove those at all, just unplug the multiplug from the end of the MAF. If the MAF is the same type as the 1.8T (which I'm pretty sure it is) then you do have to depress that lug and wiggle the plug a bit to get it off. Don't get too heavy handed with it though as I managed to snap the clip on mine taking it off :(

is it the lug on the narrow, or wide section of the plug? tried both but nowt happening really, and like you say, dont want to get too heavy handed.

thanks

MAF and MAF housing is on the far right of this pic (of Robs engine bay... this is a 1.8T but I'm pretty sure the 1.9TDI MAF looks the same)

The multiplug is the top bit with the litte ridge in the middle, the bit underneath that which is screwed into the MAF housing is the MAF itself, you can see there is a clip on the MAF just underneath that ridge... the lug on the multiplug clips into that clip. It needs to be released with a screwdriver while you wiggle the plug to pull it out.

MAF and MAF housing is on the far right of this pic (of Robs engine bay... this is a 1.8T but I'm pretty sure the 1.9TDI MAF looks the same)

The multiplug is the top bit with the litte ridge in the middle, the bit underneath that which is screwed into the MAF housing is the MAF itself, you can see there is a clip on the MAF just underneath that ridge... the lug on the multiplug clips into that clip. It needs to be released with a screwdriver while you wiggle the plug to pull it out.

thanks mate, ive just got it off. and broke the clip just like you! :-D and it ran worse than usual, so i assume that means maf is ok? ive put it back on now, but obviously as the clips bust, its not as secure as before :-/

They're a pain those clips! I broke the one on the boost pressure sensor on my intercooler as well as the one on my MAF. You can wrap a couple of long cable ties around the MAF housing and the plug to keep it tight in if you're worried about it coming out but mine seemed to be fine without.

That seems to rule out your MAF as being a problem then.

They're a pain those clips! I broke the one on the boost pressure sensor on my intercooler as well as the one on my MAF. You can wrap a couple of long cable ties around the MAF housing and the plug to keep it tight in if you're worried about it coming out but mine seemed to be fine without.

That seems to rule out your MAF as being a problem then.

thanks. ive also just checked the air filter and it looks new. (maybe i WILL make a mechanic after all! check me undoing those 2 screws and lifting the cover!) :-D

is it all pointing to gummed up vanes then? big job? :-(

Edited 30 January, 201214 yr by sadexpunk

thanks mate, ive just got it off. and broke the clip just like you! :-D and it ran worse than usual, so i assume that means maf is ok? ive put it back on now, but obviously as the clips bust, its not as secure as before :-/

Normally if you push the plug back towards the socket (ie. the opposite way than you would to actually remove it), and then press down on the clip and wiggle it you can then pull the plug off.

These VAG clips can be a PITA sometimes though - as you have just found. A large tie-wrap should should ensure it does not fall off in the future. At least if the car runs worse with it disconnected that rules out the MAF. Therefore you are back to sticky turbo vanes, n75 or a vacuum leak at possible routes of investigation.

Normally if you push the plug back towards the socket (ie. the opposite way than you would to actually remove it), and then press down on the clip and wiggle it you can then pull the plug off.

These VAG clips can be a PITA sometimes though - as you have just found. A large tie-wrap should should ensure it does not fall off in the future. At least if the car runs worse with it disconnected that rules out the MAF. Therefore you are back to sticky turbo vanes, n75 or a vacuum leak at possible routes of investigation.

are they the only 3 options then mate, as the N75 has been changed, and the garage said theyd pressure tested and cleaned hoses. can you explain in laymans terms how gummed up vanes could work sometimes, and not others?

thanks a lot

EDIT: also i should maybe mention that im losing about 50 miles to a full tank these days. used to get nearly 600miles, these days its about 540ish to a tank full. dont know if thats relevant at all.

Edited 30 January, 201214 yr by sadexpunk

are they the only 3 options then mate, as the N75 has been changed, and the garage said theyd pressure tested and cleaned hoses. can you explain in laymans terms how gummed up vanes could work sometimes, and not others?

thanks a lot

EDIT: also i should maybe mention that im losing about 50 miles to a full tank these days. used to get nearly 600miles, these days its about 540ish to a tank full. dont know if thats relevant at all.

I would not like to commit myself to those being the only 3 reasons, but they are 3 of the most common reasons, imho.

In laymans terms all metals will change size slightly when the temperature changes, and plus the amount the vanes move is controlled by the ECU for the current speed, loading, gear, air intake, amount of acceleration requested etc. Modern cars are doing lots of work in the background. It could even be a faulty ECU, but I think only the earlier TDIs suffered with that issue.

tbh: you might be running on a winter mix of fuel as well, combined with additional electrical items running in the car - headlights, fan, demister - these all draw power which comes from the battery, which has to be recharged by the alternator, which is powered by the engine, which uses diesel. A failing CTS (Coolant Temp Sensor) might be an issue as well. Does the gauge sit bang on 90 deg after 6-8 minutes of driving? The CTS has 2 feeds - one for the dash gauge and one for the ECU, sometimes just half of it can fail. Reading the coolant temp via VAG-COM/VCDS will show if this is the case.

I would not like to commit myself to those being the only 3 reasons, but they are 3 of the most common reasons, imho.

In laymans terms all metals will change size slightly when the temperature changes, and plus the amount the vanes move is controlled by the ECU for the current speed, loading, gear, air intake, amount of acceleration requested etc. Modern cars are doing lots of work in the background. It could even be a faulty ECU, but I think only the earlier TDIs suffered with that issue.

tbh: you might be running on a winter mix of fuel as well, combined with additional electrical items running in the car - headlights, fan, demister - these all draw power which comes from the battery, which has to be recharged by the alternator, which is powered by the engine, which uses diesel. A failing CTS (Coolant Temp Sensor) might be an issue as well. Does the gauge sit bang on 90 deg after 6-8 minutes of driving? The CTS has 2 feeds - one for the dash gauge and one for the ECU, sometimes just half of it can fail. Reading the coolant temp via VAG-COM/VCDS will show if this is the case.

hmmm interesting that you mention temperature. for a while now, the temp gauge has been playing up. mostly it sits at 90, but a few journeys its not got higher than 75. then when i remember to look again, its 90. today was the first time i noticed that firstly, it was sat at 78 (after 10 mins or so of driving), but i looked at it again and it had dropped to zero. few minutes later was at 78 again.

any chance this could be related to my turbo problem at all then?

thanks

Definately sounds like your CTS is shagged if it's suddenly dropping to zero then back up again!

I wouldn't have thought it would affect the turbo but it will certainly make the car run badly.

And that will be why you're getting 50 miles less to the tank.

Get a proper new (green) CTS from a dealer (or TPS) and fit it. See if that helps. They are only about £25 I think. Avoid cheapo ebay items as they had a habit of failing rather quickly.

thatd cause the engine to run badly would it. i wouldnt have guessed that, id have just thought itd be giving a wrong reading. didnt consider it might have other implications. would it just be running inefficently whilst the reading was wrong, or could it still be losing mpg whilst temp gauge was sat at 90?

easy job for someone who can undo and redo screws? or a job for the garage do you think? its provisionally booked in again on tuesday :-(

thanks

Inaccurate temperature readings being supplied to the ECU would cause incorrect fueling, and could cause other performance issues. Are previously mentioned, the CTS has 2 outputs - one to the dash gauge and the other to the ECU. When the CTS goes faulty it can send different readings.

No screws, just a clip to remove. Do it when the engine is cold, and if you are prepared and ready, you will only see a few drips of coolant come out. I changed mine in the company car park one lunchtime. There is no need to get a garage to change it do it yourself!

Remember we are only making suggestions, as we have not seen your car, nor do we know any other issues which might be having a knock-on affect. We can only work with the information provided. Are there any codes from VAGCOM? Note that if you have driven the car with the MAF disconnected, there will probably be a MAF related one, which can be cleared.

CTS location:

Edited 31 January, 201214 yr by mbames

Inaccurate temperature readings being supplied to the ECU would cause incorrect fueling, and could cause other performance issues. Are previously mentioned, the CTS has 2 outputs - one to the dash gauge and the other to the ECU. When the CTS goes faulty it can send different readings.

No screws, just a clip to remove. Do it when the engine is cold, and if you are prepared and ready, you will only see a few drips of coolant come out. I changed mine in the company car park one lunchtime. There is no need to get a garage to change it do it yourself!

Remember we are only making suggestions, as we have not seen your car, nor do we know any other issues which might be having a knock-on affect. We can only work with the information provided. Are there any codes from VAGCOM? Note that if you have driven the car with the MAF disconnected, there will probably be a MAF related one, which can be cleared.

CTS location:

thanks a lot for your help. i havent got access to VAG COM, its my garage that are reading codes. i wouldnt understand what to do. if i changed the CTS myself, would i still need to have codes cleared to notice a difference? so id still need garage anyway?

clutching at sttraws, but could there be a tiny chance that changing it will clear up the 'flat engine/ turbo vanes' problem? or should i just accept its the vanes? :-D

cheers

If you changed the CTS there would be no need to clear the fault codes for that, and if it was at fault you should see an immediate difference.

I was just making the point about fault codes that the next time your garage read them if they get a MAF related one (which they *should*), then they might tell you need a new MAF. If they do say that, then get them to check the actual MAF readings to confirm if it is faulty or not.

There are various things it could be, but given your driving style it is probably the vanes, but we have been suggesting cheaper alternatives first. Note: that if you have a vacuum leak/issue and have the turbo cleaned up, then the turbo problems will eventually reoccur unless the root cause the problem is resolved (plus stop driving like a granny all the time )

Has the 90bhp Octy even got a variable vane turbo? My sisters Mk1 Leon has the same engine and that's got a wastegated turbo... I thought the variable vane turbos were mainly on the 110bhp TDIs?

If your turbo is whistling as loud as it always has been then I wouldn't say theres a problem with the turbo at all, your flat running is down to something else (like the CTS).

Has the 90bhp Octy even got a variable vane turbo? My sisters Mk1 Leon has the same engine and that's got a wastegated turbo... I thought the variable vane turbos were mainly on the 110bhp TDIs?

Early 90s were wastegate-based, and the latter ones variable vane based. iirc, the OP's car is 2003 so I guess that puts it in the latter category.

VVT were fitted to all 110 and 130TDI mk1 Octavias (to the best of my knowledge).

plus stop driving like a granny all the time )

:-D point taken

as far as the vvt goes, the garage told me it was variable vane, and that theyre renowned for getting gummed up, so i assume he knows what hes on about :-)