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Old 17-12-09, 13:36
Monkeypuzzeled's Avatar
Monkeypuzzeled Monkeypuzzeled is offline
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T5 Post Icon Boost Pressure Regulation: Control Range Not Reached

Hey folks,

T32 2.5L TDI 130, 120k on the clock. 14 weeks of hell!

Having a hum dinger of a time since I bought my T5! Got sold a lemon by a lying eBay prick! We found a turbo problem when we test drove it, but should have thought it was a bit easy negotiating the price of a turbo off said prick.
The problem manifests itself when cruising (or attempting to) on the motorway (the only reason I didn't buy a splitty!). When I get to around 70mph, it goes into limp home mode. A quick off-on with the ignition and the turbo kicks back in again. But 70mph in 5th and 6th gear and the van is useless, unless you want to reset every 2 minutes.
Turbo replaced, all sensors replaced or swapped out with another van.
ECU remapped with standard VW 130 map.
Basically 12 weeks of head scratching with my independent garage. Been to 4 sets of "guru's", been on numerous diagnosis set-ups and I'm still left with fault code 16683 - Boost Pressure Regulation: Control Range Not Reached.

Not willing to stitch up some other poor eBay blighter, though may sell when I've got it fixed, I am no longer loving this van, the bubble is well and truly burst!

Please please please, has anybody had similar problems? or can anybody throw up some other ideas? We’ve really checked everything sensible and are starting to look at seemingly improbable.

Cheers
Monkey
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  #2  
Old 17-12-09, 18:56
oily.tom oily.tom is offline
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Default Re: Boost Pressure Regulation: Control Range Not Reached

Hi, not sure if this is related but on my van T4 2.5 tdi I had a similiar problem. I changed the MAF thinking it was that but still the same. Bit the bullet and sent it in to dealers. It turned out to be a dodgy EGR solenoid (or so I was told) been alright since.

Hope this helps.
Regards, Tom.
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Old 18-12-09, 09:43
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Rod_vw Rod_vw is offline
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Default Re: Boost Pressure Regulation: Control Range Not Reached

Monkey,

Have you tried on here http://www.ilexa.co.uk/forum/index.php?board=24.0 for some suggestions. If you go that way please note the posting protocol to save being locked out.

Rod.
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Old 04-01-10, 11:44
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Monkeypuzzeled Monkeypuzzeled is offline
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T5 Post Icon Re: Boost Pressure Regulation: Control Range Not Reached

Hey Folks,

Struggled with that link, but will try again with a bit of info.

Right, so far:-

Turbo replaced.

Ruled out the inlet and high pressure system, all hoses, filter box and turbo intercooler not blocked or leaking.

Exhaust, ruled out, had it to component parts and off.

Sensors all replaced or switched out to check they're working.

Vacuum saddle and solenoids rulled out. Switched out the solenoids. Vacuum saddle, bypassed the lot, checked and double checked no leaks.

Vacuum pump is providing -0.9bar at revs, so it's not that.

ECU guarenteed remapped with a 130 map.

I'm out of ideas, the forums are not showing this problem and I'm thinking of venturing further afield, does the Merc sprinter or such have a similar VGT turbo system? WHere else can I look?!

Thanks for your inputs.
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Old 04-01-10, 15:29
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ferretflasher ferretflasher is offline
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Default Re: Boost Pressure Regulation: Control Range Not Reached

Feel for you mate, anyone else should head this warning, NEVER BUY WORK when dealing with stuff on EVIL-BAY.......just walk away!!
It sounds like the boost pressure sensor has lost its cal range, I would propose you get a laptop running VAG-COM hooked up and go for a drive and see what the blocks are doing during some high-speed m-way running. You need to be 100% sure that the N75 control block is working and that the turbo vanes ACTUALLY move when commanded. If that solenoid is faulty then it will over boost for sure. Your problem is too much air Im sure and hence the default limp mode. Test that solenoid on the bench and make sure it clicks open when 12 volt applied....IT HAS TO WORK or its limp mode everytime.
Have a read of this thread and try to get a VAG-COM working showing live data.

http://www.ilexa.co.uk/forum/index.p...,23606.10.html

HTH

I sacked-ff the T5's several years ago now and use a VITO 639, these and the Sprinters all use variable geometry turbos, there are no other systems now to my knowledge. MB are also prone to ECU problems so dont think its just the T5 thats buggered, VITO's screw up aswell!
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Old 04-01-10, 15:36
Phatty Phatty is offline
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Default Re: Boost Pressure Regulation: Control Range Not Reached

its basically telling you that it's not producing enough boost.

fit a boost gauge and confirm what is is producing.

with these variable vane turbos they don't have a wastgate, they dump it by moving the vanes and/or opening the EGR valve. if the valve or the vanes are jammed it won't produce boost.

my mates passat 130PD just did something similar, but it was over boosting. the vanes were stuck and just needed "persuading". try and EGR blanking plate to eliminate the valve and make sure the turbo is seeing all the exhaust gasses it should be.

Need VAG COM in Yorkshire? PM me...
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Old 04-01-10, 20:27
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ferretflasher ferretflasher is offline
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Default Re: Boost Pressure Regulation: Control Range Not Reached

My understanding is the reverse to yours???
The variable geometry positions a series of vanes that change the angle of attack which the hot gases are directed onto the turbine impeller. At low and medium engines speeds the arm is in its normal rest position and allows the turbine to spin and compress air quite efficiently. At higher speeds the whole process would get carried away and basically compress so much air as to blow the engine to bits- its an un-regulated system and for a few glorious moments the engine would just produce masses of power. But to prevent that (and because theres no blow-off valve / waste-gate to let the pressure escape down the pipe) the arm moves (under the command of ECU) these vanes and makes the compressor less efficient, they are tiny things and move only a few mm but its enough to make the turbine less efficient and stop it blowing its self up. The turbine is still spinning at some 30-40000 rpm and still producing some 1.5- 1.95 bar boost whatever it happens to be but thats how much it needs to be.....any more and the engine would wreck its self....melted piston crown, NOX emissions too high, turbo damage.....these are just production line engines, not some race exotica.

Now if our N75 block is not working, the boost gets too high for safety at say 3000 rpm engine speed, the boost sensor detects this higher-than-it-should-be charge air pressure and ECU defaults to Limp Mode.

Therefore the normal run position of the VTC arm is in its OFF position, at 3000 rpm it must move to the ON position. This is how my VITO works, I have watched it on a rolling road at full chat, it dont move much..maybe 10mm.

Waste gates were in-efficient so we were told, compressing air only to dump it again when things got a bit hot. Your T5 ( and my Vito) also have EGR valves to put some hot exhaust (thats very low in oxygen content after having been used to burn the previous squirt of diesel) gas into the charge air to make the combustion temperatures lower otherwise things get very hot in there and the NOX goes too high.
The thread owner may have a problem with the EGR being permanently open, this would cause a low boost pressure and thereby give the charge-air too low pressure fault you are proposing. The fault has to be in this area. The EGR should be closed until is told to open and cool things down with mucky exhaust gas thats low in oxygen.

HTH??
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  #8  
Old 04-01-10, 20:30
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ferretflasher ferretflasher is offline
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Default Re: Boost Pressure Regulation: Control Range Not Reached

NB, I can see my turbo unit with the bonnet/hood up........its dead easy to see / reach / touch it/ etc........thats one of several why reasons I went MB
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Old 10-02-10, 12:44
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Monkeypuzzeled Monkeypuzzeled is offline
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jawdropping Re: Boost Pressure Regulation: Control Range Not Reached

Well Folks,

I'm looking for help more than ever. All my avenues of investigation have been closed.

Checked everything time and again. Last night, I replaced my latest reconned turbo with a 42k mile 2nd hand one and i still have underboost. That's the 4th turbo since i had the van (6months of hell), everytime we've been around the ancillaries and found no problem, we've been led back to the turbo.
Well, it's not that! B#gger! So, with all solenoids/actuators/inlet/exhaust/turbo/vacuum system/ecu/map (etc, the list goes on!) checked, it's time to get inside the engine!

I can't imagine that a work cam could reduce boost to the extent that I have without being really noticeable. Bus what else should i look at?

Please please please, can somebody out there help me???
Cheers,
Tom
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Old 10-02-10, 12:46
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Dazboi Dazboi is offline
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Default Re: Boost Pressure Regulation: Control Range Not Reached

do you want to bring it down to me and ill get one of my guys onto it, see what they can find out for you?

Been around the block a bit
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