New TQS Owner & Project

[Samuel c5 Q]

The pancake one is the pressure regulating valve and connects to the turbo intake pipe and the PCV is the positive crankcase ventilation valve and fits in a rubber t piece that joins the crank breather system to the vacuum system and the intake pipe via the PRV. As said it shouldn't stop it starting but a failed PCV can cause a boost pressure drop.

 

[MaverickTDi]

i think its actually the short rubber sections that seemed to be deteriorating, perhaps due to ethanol in the fuel. The hard lines are aluminium and shouldnt really degrade.

I've probably got a fuel rail in the garage if you want one, i wouldnt go buying a new regulator, they're not usually something that will fail.

The filter is under the car near the drivers rear wheel. Its a ***** to get at and the securing nut is usually siezed in. I think removing the tank strap and levering the tank down a bit is the best way to get into it.

Remember these cars have no EML. So if you've not checked for codes that should be the first step!

I'll jack the car up and inspect the rubber sections tonight.

What can fail within the fuel rail that might cause my issue? I'll have a good look tonight but have never noticed a fuel leak before.

Yeah, I plan to dig out my old laptop tonight and see what codes I get.

Cheers.


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[MaverickTDi]

The pancake one is the pressure regulating valve and connects to the turbo intake pipe and the PCV is the positive crankcase ventilation valve and fits in a rubber t piece that joins the crank breather system to the vacuum system and the intake pipe via the PRV. As said it shouldn't stop it starting but a failed PCV can cause a boost pressure drop.

Cheers mate

Well there's no boost issue. It pulls well with no flat spots or hesitations throughout the rev range.

As said the issue appears to be with starting.


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[aragorn]

The pancake one is the pressure regulating valve and connects to the turbo intake pipe and the PCV is the positive crankcase ventilation valve and fits in a rubber t piece that joins the crank breather system to the vacuum system and the intake pipe via the PRV. As said it shouldn't stop it starting but a failed PCV can cause a boost pressure drop.

I think you have terms mixed up.

Most people call the pancake valve the "PCV", though your right in that really its a pressure regulating valve, and PCV actually refers to the system as a whole. "PCV valve" is a common term to describe the pressure regulating valve thats situated in the turbo intake.

The valve inside the rubber T piece is simply a check valve. It closes when the manifold hits boost, and stops the boost pressure pressurising the crank case and/or breather system.

 

[aragorn]

I'll jack the car up and inspect the rubber sections tonight.

What can fail within the fuel rail that might cause my issue? I'll have a good look tonight but have never noticed a fuel leak before.

You likely wont see anything, they break down internally due to contact with the fuel and the bits of rubber float along and get stuck in the regulator.

My point about the rail, was that instead of buying a new regulator, i've probably got a rail with regulator spare. i dont believe thats related to your starting issue though.

 

[MaverickTDi]

Aragorn - you mentioned in a previous post about the throttle body possibly causing the rough idle.

What in particular would I be looking for within the throttle body? Butterfly valve movement?

Cheers.


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[MaverickTDi]

You likely wont see anything, they break down internally due to contact with the fuel and the bits of rubber float along and get stuck in the regulator.

My point about the rail, was that instead of buying a new regulator, i've probably got a rail with regulator spare. i dont believe thats related to your starting issue though.

Do you think the FPR is not related?

What checks would you carry out?


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[aragorn]

fault codes first!

 

[MaverickTDi]

fault codes first!

Here you go;

I've now cleared the fault. Car starts fine now - tried twice;



Is the fault code registered related to the CTS? And would a historic fault log continue to cause the issue? As it seems odd that since I cleared the code it starts fine....


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[Samuel c5 Q]

It might be the fuel trims I noticed that when mine was running rough it ran better after the codes had been cleared which resets the fuel trims.

 

[MaverickTDi]

It might be the fuel trims I noticed that when mine was running rough it ran better after the codes had been cleared which resets the fuel trims.

Interesting....

We'll see what happens over the next few days I guess.

Cheers.


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[aragorn]

http://wiki.ross-tech.com/wiki/index.php/00561

The "hidden" code is fuel trim related as mentioned.

Additive trims are often air leaks and similar things.

You need to drive around a bit and see what the fuel trims do.

 

[MaverickTDi]

http://wiki.ross-tech.com/wiki/index.php/00561

The "hidden" code is fuel trim related as mentioned.

Additive trims are often air leaks and similar things.

You need to drive around a bit and see what the fuel trims do.

Well that would explain the poor idling.

Ok, I'll take it to work tomorrow and rescan when I get home. I only have the very basic VCDS so that's all I can do.

Update to follow.

Cheers.




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[MaverickTDi]

Well after a day of use and several engine start stops no faults have been logged;

I'll obviously keep an eye on it to make sure it's not something that deteriorates over time.

See what happens I guess.



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[MaverickTDi]

Just turned the car over and with the drivers door open I heard this bubbling sort of noise - had a look under the car and it's coming from this;

It sits just rear of the drivers door hinge underneath the car - what is it?

When I put my finger over the end I can feel a very light suction - said the Vicar

Any ideas?

Cheers.


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[Samuel c5 Q]

Charcoal canister fresh air vent or pull in maybe. I've pulled a spare one out but haven't studied it closely yet.

 

[MaverickTDi]

Charcoal canister fresh air vent or pull in maybe. I've pulled a spare one out but haven't studied it closely yet.

Should it make a noise though?

Best way I can describe it is when the last bit of water goes down the sink like a glug noise - odd I know


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[Samuel c5 Q]

It will be constantly active. If it isn't then there's something wrong. I'm not sure what noise it should be making nothing too obvious at a guess. As I say I'm still to work that part if the system over.

 

[MaverickTDi]

It will be constantly active. If it isn't then there's something wrong. I'm nit sure what noise it should be making nothing too obvious at a guess. As I say I'm still to work that part if the system over.

Ok mate - cheers


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[aragorn]

Not ever heard bubbling from there, but yes its the vapour thingy from the carbon can.

 

[MaverickTDi]

Not ever heard bubbling from there, but yes its the vapour thingy from the carbon can.

I'll try and get a vid to show you tomorrow.

It sounds like there's fluid somewhere in the system - is that normal?


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[MaverickTDi]

Not ever heard bubbling from there, but yes its the vapour thingy from the carbon can.

Where is the carbon can located?

Cheers.


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[Samuel c5 Q]

Inner arch on the drivers side. I noticed I wild lot of heat through the wing where the hose from the carbon can enters the bay and joined with the n80 valve. Right where the shut line is more or less. Can't explain fully what the cause was. If it was engine or turbo heat you would think it would not be quite so located to a spot the size of your hand.

It's behind the arch liner.

 

[MaverickTDi]

Whilst hoovering the engine bay out of tree debris I happen to notice this;

Seems the harness protection did its job and there was no damage to the actual cables.

Post fix;

I also noticed that the vacuum hose from the intake manifold to the FPR was a bit tatty;

The cars hesitant starting reared its head again yesterday - just scanned it and no fault codes found.

Is there any other menu within VCDS Lite that I can use, other than 'Auto Scan', that may find faults?

Cheers.




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[aragorn]

Go into the engine controller and look at the fuel trims in measuring blocks and see what they show.

 

[MaverickTDi]

Go into the engine controller and look at the fuel trims in measuring blocks and see what they show.

Having gone into the 'Engine Controller' menu and flicked through all the 'Groups' of which I couldn't find any relating to fuel trims as VCDS Lite only allows you to go to Group 25, here's what I got with the engine running at idle;

I'll admit I have no idea if any of those readings are good or if they show something is not well - input here greatly appreciated.

Cheers.


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[MaverickTDi]

New silicon hose turned up today to replace the hose that runs from the intake manifold to the FPR.

Old hose;

Although the outer braiding is past it I couldn't see any obvious splits in the pipe itself.

To see if this was causing the hesitant staring I thought I'd try and start the car with no hose fitted and it started fine - kind of throws that theory out the window.

New hose fitted;

Any idea what that hose is in the pic? Reason I ask is I found this half hanging out where it goes into the bulk head.

Cheers.


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[Samuel c5 Q]

Brake booster vacuum hose.

 

[MaverickTDi]

Brake booster vacuum hose.

Cheers

I could take an educated guess at what it is / does based on description but could you tell me its purpose and implications if not working etc?

Thanks.


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[MaverickTDi]

Think this summarises nicely;

'This hose handles the vacuum that the engine produces so that the booster can assist the pedal input of the driver. The vacuum "softens" The brake pedal so that the driver doesn't need much effort in braking. A leaking or broken Brake Booster Vacuum Hose won't get the vacuum flowing from the engine to the booster and might result in reduced amount of assist or total failure of the braking system. '


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[Samuel c5 Q]

Sounds a bit dodgy doesn't it?

 

[MaverickTDi]

Sounds a bit dodgy doesn't it?

What does?

My brakes are as they need new discs and pads all round and I have always thought I needed to put a little extra pedal in to get them to bite but I've always put that down to the poor condition.


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[Samuel c5 Q]

The brakes failing completely because of one plastic hose bit.

Your brakes are 288 mm fronts and 245mm rears? My a6 has 312mm front and 245mm rears and feels adequate/satisfactory as in strongish giving good confidence.

 

[MaverickTDi]

The brakes failing completely because of one plastic hose bit.

Your brakes are 288 mm fronts and 245mm rears? My a6 has 312mm front and 245mm rears and feels adequate/satisfactory as in strongish giving good confidence.

Yeah I thought that was a bit extreme.

Yeah completely stock all round. I've got A6 front discs and pads to do the upgrade just need to source some mk1 TT carriers then good to go.


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[Samuel c5 Q]

Would a6 carriers not do the job or is the offset/mounting point different?

 

[aragorn]

group 8 contains the fuel trims. They both look fine.

 

[MaverickTDi]

When changing the brake discs (front & rear) are the abs rings usually transferred over?

Cheers.


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[Samuel c5 Q]

No.

 

[MaverickTDi]

No.

So I need to buy abs rings when fitting new discs?




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[Phil_R]

No, the ABS rings are on the driveshafts so are not affected by changing discs