Td4 turbo problem?

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TheKeymeister

TheKeymeister

Active Member
Posts
772
Location
Lincolnshire
Hi, this is a bit of a long one...

About 2 weeks ago I had a problem on my 2005 Td4 where there was a massive dip in power for about 3 seconds when going uphill then it came back in again, I thought nothing of it, but then it happened again, and progressively kept happening more and more until it happened at anything over 2000rpm unless you 'nursed it' up.

First off I replaced the vacuum hose from the reservoir to the actuator, unfortunately I broke the output nipple on the vacuum reservoir so I bodged it and plugged the reservoir, and connected the turbo actuator pipe to where the EGR solenoid usually connects. Apparently this would be ok but flat above 3000rpm. Unfortunately it made it even worse, it happened at about 1750rpm instead, and I got caught out trying to get up a hill in Louth at 15mph in second gear with it refusing to rev.

I then disconnected the vacuum feed to the turbo actuator and plugged it, and things improved, it would only happen in 4th and 5th at around 2500rpm upwards.

Today a new turbo actuator arrived in the post, and a reel of vacuum hose, so I set to and replaced all the vacuum lines and fitted the new actuator. The vacuum pipe to the EGR solenoid was completely split open where it had rubbed through on something near the front of the engine. As my vacuum reservoir is still busted, I plugged the actuator on to the EGR's vacuum connector again and took it for a spin. It went back to losing power at 1750rpm again, so I disconnected the actuator's vacuum feed again and it went back to only doing it in 4th and 5th at 2500rpm.

I've got a new vacuum reservoir waiting at the post office for me, which I will pick up and fit tomorrow, but I'm not sure it will make much difference. I am starting to wonder whether the turbo is at fault, maybe the vanes sticking, is there an easy way to get at it to clean it out and free it up if that's what it is?

Another thing I noticed was with the engine running, if you remove the oil filler cap, there is a constant puff puff puff from it, is this normal, I have heard this can be caused by a blocked PCV filter, but I have fitted the cyclone mod. Could it have gone faulty? I am having no problems with the dipstick popping out or anything.

Parts I have changed / things I have done so far are:-
-Oil&filter/air filter/fuel filter changed
-EGR blanked using proper kit and inlet manifold removed and cleaned out
-BMW PCV cyclone mod fitted
-Intercooler hoses on front of engine replaced
-MAF replaced for new Bosch one
-All vacuum hoses replaced
-Turbo actuator replaced
-Checked and cleaned fuel rail sensor

Parts ordered and in the post:-
-Low pressure fuel pump
-Vacuum reservoir

Thanks in advance for any help, this is really winding me up now!
 
Any leak in a vacuum pipe will cause boost issues. There has to be sufficient vacuum available to operate the turbo vanes. So first thing it to sort out every vacuum pipe. I would think it wise to fit an EGR bypass. A sticking EGR valve can cause similar issues to what you are having.
 
The EGR has been blanked off in the air intake with a bypass piece which has a stub for the vacuum pipe to it, but the EGR control solenoid is still connected, I believe it can throw up a fault code if it isnt? Either way all the vacuum pipes are brand new now. I will see if the new vacuum reservoir fixes tomorrow it but I'm not hopeful!
 
TheKeymeister said:
The EGR has been blanked off in the air intake with a bypass piece which has a stub for the vacuum pipe to it, but the EGR control solenoid is still connected, I believe it can throw up a fault code if it isnt? Either way all the vacuum pipes are brand new now. I will see if the new vacuum reservoir fixes tomorrow it but I'm not hopeful!
Click to expand...
The vacuum reservoir is a likely culprit. But keep us updated.
Thing I'm most amazed at, you found a hill in Louth:eek:
Mike
 
TheKeymeister said:
Hi, this is a bit of a long one...

About 2 weeks ago I had a problem on my 2005 Td4 where there was a massive dip in power for about 3 seconds when going uphill then it came back in again, I thought nothing of it, but then it happened again, and progressively kept happening more and more until it happened at anything over 2000rpm unless you 'nursed it' up.

First off I replaced the vacuum hose from the reservoir to the actuator, unfortunately I broke the output nipple on the vacuum reservoir so I bodged it and plugged the reservoir, and connected the turbo actuator pipe to where the EGR solenoid usually connects. Apparently this would be ok but flat above 3000rpm. Unfortunately it made it even worse, it happened at about 1750rpm instead, and I got caught out trying to get up a hill in Louth at 15mph in second gear with it refusing to rev.

I then disconnected the vacuum feed to the turbo actuator and plugged it, and things improved, it would only happen in 4th and 5th at around 2500rpm upwards.

Today a new turbo actuator arrived in the post, and a reel of vacuum hose, so I set to and replaced all the vacuum lines and fitted the new actuator. The vacuum pipe to the EGR solenoid was completely split open where it had rubbed through on something near the front of the engine. As my vacuum reservoir is still busted, I plugged the actuator on to the EGR's vacuum connector again and took it for a spin. It went back to losing power at 1750rpm again, so I disconnected the actuator's vacuum feed again and it went back to only doing it in 4th and 5th at 2500rpm.

I've got a new vacuum reservoir waiting at the post office for me, which I will pick up and fit tomorrow, but I'm not sure it will make much difference. I am starting to wonder whether the turbo is at fault, maybe the vanes sticking, is there an easy way to get at it to clean it out and free it up if that's what it is?

Another thing I noticed was with the engine running, if you remove the oil filler cap, there is a constant puff puff puff from it, is this normal, I have heard this can be caused by a blocked PCV filter, but I have fitted the cyclone mod. Could it have gone faulty? I am having no problems with the dipstick popping out or anything.

Parts I have changed / things I have done so far are:-
-Oil&filter/air filter/fuel filter changed
-EGR blanked using proper kit and inlet manifold removed and cleaned out
-BMW PCV cyclone mod fitted
-Intercooler hoses on front of engine replaced
-MAF replaced for new Bosch one
-All vacuum hoses replaced
-Turbo actuator replaced
-Checked and cleaned fuel rail sensor

Parts ordered and in the post:-
-Low pressure fuel pump
-Vacuum reservoir

Thanks in advance for any help, this is really winding me up now!
Click to expand...
I'm having similar problem my orange light comes on when I'm towing or going up a hill when I press accelerator again it goes off then comes back on was told it is a turbo actuator problem?
 
Well as expected I replaced the vacuum reservoir, connected it all up, and it's gone back to a huge loss of power at 1750rpm and being basically undriveable. As soon as I disconnect the vacuum to the turbo actuator it doesn't lose power until 2500rpm again. I also tried unplugging the MAP sensor but it made no difference at all. The new LP fuel pump hasn't arrived yet, if that doesn't cure it, I think I will have to try using some of that turbo cleaner stuff to see if it changes anything.

Skinny Mike said:
The vacuum reservoir is a likely culprit. But keep us updated.
Thing I'm most amazed at, you found a hill in Louth:eek:
Mike
Click to expand...
The Louth bypass is probably the biggest hill round here!
I live slightly further south in the Lincolnshire fens, but have to travel to Humberside for work, as there's a few hills that way I had to swap with the other half's Seat Arosa 1.0 as it was better up hills, and she took the Freelander as her drive to work is perfectly flat...

Carl powell said:
I'm having similar problem my orange light comes on when I'm towing or going up a hill when I press accelerator again it goes off then comes back on was told it is a turbo actuator problem?
Click to expand...
Sounds similar to my issue other than I'm not getting an engine management light, I have replaced the actuator but it hasn't gone away
 
TheKeymeister said:
Well as expected I replaced the vacuum reservoir, connected it all up, and it's gone back to a huge loss of power at 1750rpm and being basically undriveable. As soon as I disconnect the vacuum to the turbo actuator it doesn't lose power until 2500rpm again. I also tried unplugging the MAP sensor but it made no difference at all. The new LP fuel pump hasn't arrived yet, if that doesn't cure it, I think I will have to try using some of that turbo cleaner stuff to see if it changes anything.


The Louth bypass is probably the biggest hill round here!
I live slightly further south in the Lincolnshire fens, but have to travel to Humberside for work, as there's a few hills that way I had to swap with the other half's Seat Arosa 1.0 as it was better up hills, and she took the Freelander as her drive to work is perfectly flat...


Sounds similar to my issue other than I'm not getting an engine management light, I have replaced the actuator but it hasn't gone away
Click to expand...

What year is it? Have you read the codes?
Have you checked all the boost pipes. Sounds like boost is building, then a split pipe is allowing the boost to fall off. A split elbow pipe pipe will cause similar symptoms.
 
Nodge68 said:
What year is it? Have you read the codes?
Have you checked all the boost pipes. Sounds like boost is building, then a split pipe is allowing the boost to fall off. A split elbow pipe pipe will cause similar symptoms.
Click to expand...

Its a 2005 model, unfortunately I gave the Hawkeye I borrowed back two days before this problem started. The only thing I have diagnostic wise is VCDS which has a generic OBD2 scan function, it doesn't show any codes, but it doesn't show much info at all really.

I have replaced all but one of the boost pipes after one split, it doesn't seem the same as when I had a split boost pipe before, that was a gradual lack of power and a hissing noise. This lack of power is like a limiter cutting in suddenly, I will try and get a video of it. I have heard the ECU can cut the fuelling if the MAP sensor reports excessive boost, it sounds like this is what it could be. My thinking to this is that with the turbo vacuum hose disconnected it is at minimum boost so it only happens at high revs. With the turbo vacuum hose connected, the turbo pressure is increased earlier in the rev range hence it happening at around 1750rpm. I've also heard that it could happen with excessive crank case pressure but not sure on this one especially as I have fitted the cyclone breather.
 
turbo vac. solenoid .. and filter .. been checked ?
.....................................................................................
 
I also tried unplugging the MAP sensor but it made no difference at all.
Click to expand...
thinking that action .. causes the ecu to replace map-output with default data in the ecu ..
(*maybe ) sets the map pressure at 900 millibar ..
causing a reduction in power ..
not sure if engine dash light comes on .. or not

i.e. maybe the map sensor needs a clean out .. or replacement ..
could it get somehow stuck in a high or low reading somehow ??

* was reading up on boost 'n map sensor yesterday ..
would have to recheck for the above to be correct :)

( edit + pic )

td4_map_fl1.jpg


perplexing issue .. after reading thru the lot

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
Last edited:
I have heard the ECU can cut the fuelling if the MAP sensor reports excessive boost, it sounds like this is what it could be.
Click to expand...

it's usually a sticking vane actuator that causes that .. over-boost ..
going by past posts on the issue

sorry .. just seen you'd replaced that
Turbo actuator replaced
Click to expand...
````````````````````````````````````````````````
 
Right, I've been out and had a play, and I think we're getting closer to the problem...

I downloaded some better diagnostic software and plugged the laptop in and monitored the live data. What I have found is that this sudden dip in power happens when the MAP sensor registers anything above 120kPa. With the turbo vacuum hose disconnected it takes longer for it to get to this value, presumably because the turbo is stuck on minimum boost. With the turbo vacuum hose connected, it still happens at anything above 120kPa, but it happens at less RPM due to turbo kicking in earlier. And the effect of 'nursing it' up to speed just means that the MAP value builds up gradually.

It is reading around 98kPa at idle, so 120kPa at not even maximum boost doesn't sound excessive, but maybe I'm wrong. Next stop will be to look into MAP sensor values to see if the sensor is duff, or if something is causing excess pressure in the inlet manifold instead. Could a damaged PCV cyclone possibly cause excess pressure in the inlet somehow?
 
so 120kPa at not even maximum boost doesn't sound excessive
Click to expand...
17.4 psi map .. ( 120kPa ) ..
that's a lite go-pedal cruise at 60 mph

max. is about 32 psi map
not sure what the max allowable by the ecu is ..

i.e. not confusing with 'boost'
if a 'boost' .. then 120kpa / 17 psi be near max boost
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
'map' value = atmospheric + added boost
( manifold absolute pressure )
 
Last edited:
I can't seem to find the ECU's acceptable range for the MAP sensor, but this page indicates a new sensor will read between 25 and 250kPa so I would imagine 120kPa is nowhere near excessive.

The only thing I can think of is that something is happening to make it shoot up massively when it gets to 120kPa and my OBD scanner isn't picking it up in time. I wonder if the one remaining intercooler pipe is collapsing in on itself when the turbo is running at higher boost causing high pressure in the inlet?! I'll be able to eliminate that thought as soon as the final remaining new pipe arrives!

Any other thoughts and/or suggestions are most welcome at this point!
 
but this page indicates a new sensor will read between 25 and 250kPa so I would imagine 120kPa is nowhere near excessive.
Click to expand...
so if that's a ' map ' value .. the 120kpa map .. represents about 20.6kpa of 'boost'
( 17psi 'map' .. 3 psi 'boost' aprox )
i.e. lite go-pedal hi-way cruising

what if .. the map sensor got stuck at the 120kpa reading ..
and won't read any higher
and driver then demanded more power ..
potentially .. the ecu will simply not allow more fuel in ?

that might fit the results you had playing around with vacuum hoses
as in the OP ..

just thinking aloud as it were ..
i don't know the particulars of how the ecu responds to various occurences

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

re this :
Another thing I noticed was with the engine running, if you remove the oil filler cap, there is a constant puff puff puff from it, is this normal
Click to expand...
normal methinks ..
mine does it ( bmw replacement thingy ) ..
take the oil cap off .. it be a far more convenient way for the gases to escape
i.e. versus the smaller orifice of the breather system ..
so yeah .. engine running .. oil cap off .. you'll feel the engine pumping the crankcase

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

thought i saw .. then on re-read couldn't find it ..
regarding turbo hoses .. and the possibility of internal collapse

the hose from turbo to intercooler has been reported as to delaminating inside
( one or two .. now ancient .. forum posts
( not a regular issue ..

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
Parts ordered and in the post:-
-Low pressure fuel pump
-Vacuum reservoir
Click to expand...

the LPFP .. if it fails ..
can give symptoms of hitting a brick wall regarding engine rpm ..

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
Had a very simler prob. Turned out to be a semi blocked injector. Pull the power leads one at a time at idle. It will either throw a benny or there will be no change . If no change thats the one. Simple test before you spend any more money. Still dont understand why it run so well with an injector down. Maybe the system compensates for the duffer to a point. When i removed the offender you wouldent think any fuel at all would pass through but it must have. Any way worth a try
 
Overboost then limp mode? The brick wall you're hitting is the ECU cutting fuelling. Something's wrong with the boost control mechanism. Watch it through the driver's wheelarch while someone revs the engine - it should move about 20mm.

Blocked vent pipe/filter?
Are you sure there's vacuum available at the solenoid?
Is there power to the solenoid when revving? This is PWM but a multimeter would do.
Is the actuator/vane mechanism stuck? Grab it with pliers and move it, or apply vacuum with a pump.
 
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