Turbo Issue

[smbbob]

Hi, i am new to this forum so sorry if this problem is already posted but I did not find any related problem.

So i have a 406 coupe 2.2 HDi Manual with 120,000 Miles, and the Turbo is not boosting under 2500-3000 Revs, before it was already boosting at about 1200-1300 Revs.
No Limp Mode or other Engine checks are on the dashboard. Even the spooling sound is not their anymore under 3000 revs.
I have checked with a local mechanic and connected with the laptop and no errors that have to do with turbo's poped up. The only Error was a fault in the exhaust temperature.
I have also checked the MAF Sensor as i read on another forum from here that this was a major issue but it has nothing to do with this as it was also changed.
I have noticed that the inlet has 2 butterflies on top of each other, does anyone know why there are 2? Is it one of them for low boost revs and the other for high boost revs? As i noticed that that one of the butterflies (the bottom one) is always closed no matter on how revs you are going, so i thought that it was something wrong from that butterfly. I tried to stick a piece of metal in it so i stuck the butterfly wide open and connected everything and tried it out, but still no boost under 3k revs..

Just for you to know the car Particular filter was removed and Deleted from the ECU, De-Cat and also at the moment no rear factory muffler. Could this be as there is no back pressure? Although all this was removed about 3 months ago and the turbo problem occurred last week.

Im all out of ideas.. would be very nice to finally find a solution to this..!

[rwb]

Hi & welcome.

You're in the right place.

This screams vacuum leak.

The 2.2 HDi is fitted with a variable vane turbo which is controlled by the vacuum system -- which also controls the two intake butterflies (these are called air dosers). Problems with the vacuum system are very common, it's very sensitive to leaks, and it's a common modification to simplify it. A read of Kelvin's thread (which has a nice diagram) will give you the idea and get you familiar with the terminology.

[smbbob]

Hi RWB and thanks for helping out!,

So it is perfectly normal that on of the air dosers remain closed even when i am throttling the car from the engine bay?

And for TESTING purposes only can i hold the swirl valve wide open to see if there is boost coming in on low Revs? or am I out of point?

Dont know if this is possible but could it be the turbo actuator be stuck and it only opens when I over rev the engine?

[PeterN]

Are you sure that the new MAF sensor was good only they are the classic symptoms of MAF failure.

Peter

[smbbob]

Are you sure that the new MAF sensor was good only they are the classic symptoms of MAF failure.

Peter

Yes im sure Peter as when removing the MAF sensor switch it immediately pops an error on the dash

[gumby6371]

And for TESTING purposes only can i hold the swirl valve wide open to see if there is boost coming in on low Revs? or am I out of point?

You should be getting into boost long before the swirl actuator moves at 2100RPM.

To track down a vac leak I'd unplug and blank everything except for the turbo EV and see if you get boost pressure in the pipes, if you do then slowly connect things back up one at a time to find the leak. If you have no boost with just the turbo connected it's the EV or actuator.

As you've had the DPF mapped out and presumably EGR as well I don't think the dozers are doing a hell of a lot anyway so I suggest you blank everything in the vac system except turbo EV, swirl EV and obviously brake servo. A tidy way to do this is find a 110 in the breakers and liberate the vac line from that as it has the right number of 'T' junctions for your modified system.

Having said all that I believe the 2.2 wastegate is closed by default and needs vac pressure to open which is why vac leaks give over boost problems in most cases (at least mine did). The vac system mods are well worth doing regardless but I am presuming that you or your mechanic have eliminated the inter cooler and it's pipework before looking at the vac system??? I have a nice moist patch (ooerrr!) under my inter cooler at the moment, it boosts but not as hard as it should.
The replacement is sitting in the shed waiting to be fitted, but it's such a difficult and complicated thing to fit I keep putting it off!!! (please note the phrase 'it's such a difficult and complicated thing to fit' should read 'very easy but I'm too lazy')

[smbbob]

And for TESTING purposes only can i hold the swirl valve wide open to see if there is boost coming in on low Revs? or am I out of point?

You should be getting into boost long before the swirl actuator moves at 2100RPM.

To track down a vac leak I'd unplug and blank everything except for the turbo EV and see if you get boost pressure in the pipes, if you do then slowly connect things back up one at a time to find the leak. If you have no boost with just the turbo connected it's the EV or actuator.

As you've had the DPF mapped out and presumably EGR as well I don't think the dozers are doing a hell of a lot anyway so I suggest you blank everything in the vac system except turbo EV, swirl EV and obviously brake servo. A tidy way to do this is find a 110 in the breakers and liberate the vac line from that as it has the right number of 'T' junctions for your modified system.

Having said all that I believe the 2.2 wastegate is closed by default and needs vac pressure to open which is why vac leaks give over boost problems in most cases (at least mine did). The vac system mods are well worth doing regardless but I am presuming that you or your mechanic have eliminated the inter cooler and it's pipework before looking at the vac system??? I have a nice moist patch (ooerrr!) under my inter cooler at the moment, it boosts but not as hard as it should.
The replacement is sitting in the shed waiting to be fitted, but it's such a difficult and complicated thing to fit I keep putting it off!!! (please note the phrase 'it's such a difficult and complicated thing to fit' should read 'very easy but I'm too lazy')

Hi, i dont believe this is a leak problem as this is not always happening, It sometimes occurs the problem and sometimes it works perfectly. Boosting at 1200 revs with no problem what so ever. If this is a leak im guessing that the problem will remain right?

[Doggy]

Could be a vacuum problem, or a sticky turbo actuator. On these cars, you need vacuum to REDUCE the boost, a serious vacuum leak will usually result in reasonable low speed performance, but intermittent overboost problems at higher engine speeds.

Beware of low-cost MAF's, a few have had to get an OE replacement after shelling out for a cheap one first. Ideally, you want to borrow a known good one for a few minutes.

Post you location, someone local may be able to help.

[smbbob]

Could be a vacuum problem, or a sticky turbo actuator. On these cars, you need vacuum to REDUCE the boost, a serious vacuum leak will usually result in reasonable low speed performance, but intermittent overboost problems at higher engine speeds.

Beware of low-cost MAF's, a few have had to get an OE replacement after shelling out for a cheap one first. Ideally, you want to borrow a known good one for a few minutes.

Post you location, someone local may be able to help.

I tried 2 known good MAF's and still same stuff happening , It makes much more sense that its a sticky actuator knowing the way its behaving. Is there a way of cleaning this ?

[GingerMagic]

Hi, the intercooler is a 30 minute job to swap - its a nice beginners fix..
I can post up some instructions if needs be....

The turbo EV can be swapped with a known working EV and the result on a test drive will be immediate.

I believe there is a 'T' piece in the vac system slightly hidden by the servo, worth checking all the pipework a bit at a time, as Gumby says, also the reservoir can leak, so bypass this too - as per my 2nd ' current layout ' diagram on my thread.

Kelv.

[smbbob]

engine 2-2L HDi.jpg

Inter cooler was check for leaks and also replaced just to make sure but still no change

Can anyone tell me if this is correct... I unpluged the Valve that is located on the bulkhead ( where there are 2 valves, 1 for the turbo and another for the EGR) Should the Valve going to the turbo be Vibrating alot when i Re plugg it in??

I posted a picture of where the valve is so maybe it would be easier for you to know what valve im talking about

[GingerMagic]

Hmmm - there should be 3 valves on the bulkhead, do you have a bracket for 3?

Yes they have been known to vibrate, even get warm but I don't know if this is normal as I haven't really checked mine ' in action ' when stationary. Maybe this is why your problem is intermittent as, like you say, a boost leak would be permanently lacking.

Have you checked the MAP sensor and pipe? Its the little black box with Denso written on it just above the intercooler, its an easy swap with a known good / borrowed one - also the tiny pipe that feeds it can be split which gives false boost info to the Denso.

I still favour the dodgy valve if your problem is intermittent.

Just for the record, the air-doser at the inlet has 2 butterflies which are chosen and opened buy the ECU/valves depending on air temperature. One butterfly opens in the colder 'intercooler' feed if the weather is hot, the other butterfly is in the 'bypassed through a heated pipe' feed if the weather is cold. Its more complex than that but this is the basic principle.

[Doggy]

The vibration's very possibly normal.
All the valves with the exception of the swirl flap and bypass heat exchanger butterfly are modulated, (turned on/off rapidly to give the same effect as opening partially).
The devices they control, (turbo, EGR, intercooler/inlet manifold butterfly), need to be controlled in this way, the other two are 'all or nothing'.

[smbbob]

Hmmm - there should be 3 valves on the bulkhead, do you have a bracket for 3?

Yes they have been known to vibrate, even get warm but I don't know if this is normal as I haven't really checked mine ' in action ' when stationary. Maybe this is why your problem is intermittent as, like you say, a boost leak would be permanently lacking.

Have you checked the MAP sensor and pipe? Its the little black box with Denso written on it just above the intercooler, its an easy swap with a known good / borrowed one - also the tiny pipe that feeds it can be split which gives false boost info to the Denso.

I still favour the dodgy valve if your problem is intermittent.

Just for the record, the air-doser at the inlet has 2 butterflies which are chosen and opened buy the ECU/valves depending on air temperature. One butterfly opens in the colder 'intercooler' feed if the weather is hot, the other butterfly is in the 'bypassed through a heated pipe' feed if the weather is cold. Its more complex than that but this is the basic principle.

Hi Ginger Magic, yes there are 3 Valves on the bulkhead. No I havent checked the Map Sensor yet to be honest.. Will see if i can borrow one and try it out

What dodgy Valve are you saying? the first one on the left on the bulkhead ?

bdw, by blanking the EGR from the inlet manifold does this totally disable EGR? Is this good enough to eliminate the EGR from Turbo issue?

Thanks for the explanation about the 2 Dosers ! I live in Malta and its currently summer here ( VERY HOT WEATHER 35 Degrees Celsius and over) and only the top air doser seems to be working. Totaly no response from the bottom one ( which seems to be from the inter cooler?)

Could this possibly be a sticky turbo actuator?

Another quick question.. the variable blades on the turbo are controlled by what exactly? One of the Valves on the bulkhead?

Could this be the blades inside the turbo be stuck due to sludge or something like this ?

Sorry for all these questions but i realy need a solution.. Fuel economy is going insane.. 14 Liters of Diesel are going with 65-70 miles..

[GingerMagic]

Hi, yes the valve on the left. The part number should be looking for a replacement is 1628 HC, all the ones on the bulkhead have the same part number on ServiceBox.

There are 2 pipes on this valve - 1 runs up to the vacuum reservoir under the servo - the other disappears out of sight behind the engine. This one is the one that closes the turbo wastegate ( I think ) so if it is a dodgy valve then the wastegate is stuck open so affecting the boost. The valve closes the wastegate when activated.

Blanking the EGR at the inlet manifold is okay but you will also need to blank/remove the vacuum that feeds it. Simply remove the small pipe attached to the EGR and stuck something in the end... I chose to blank both ends of the EGR just to be safe as I had the car off the road for a month so there was plenty of time.

The EGR shouldn't affect the turbo but it can have its own problems so blanking it eliminates any potential issues

As for the vanes, I think they open automatically at higher revs ( I used to think the valve did it but I was wrong ) so what I do to lubricate them is to remove the soft black pipe from the rigid plastic air feed - there is an angled hole just after the MAF - and squirt WD40 into it when the engine is running. One hand to squirt and the other hand to rev the engine - this is what the VW boys do......

It is possible to remove the air-doser completely, these aren't required if EGR is blanked, myself, Doggy, Gumby have all done it with good results.