Turbo Boost Fault.

Now the head gasket appears to be OK (I hope....), it's time to move onto the next annoying little bug...

Our TD4 sometimes seems to loose power for a few seconds, before the turbo can be heard spooling up again, and normal service is resumed. For the last few weeks, this has sometimes been accompanied by the Mil lamp illuminating. Usually as power is re-applied at 50-70 mph. After a visit to a LR indy, and being relieved of £45, they have confirmed my suspicions, and diagnosed a boost pressure fault code. They couldn't ID the exact cause, and only suggested starting replacing the cheapest parts first, before possibly replacing the complete turbo unit...!

As the fault isn't always present, trying the soleniod test recommended above wouldn't reveal anything. Has anyone else experienced this? Do the soleniod's stick intermittently, or will it just fail completely? Ifv the vanes are a bit sticky, can they be cleaned using additive products, or is it a complete strip down job?

I intend (weather permitting), to get the ramps out next week, and try to lub and exercise the turbo linkages, clean the soleniod connector, check the vacuum hoses for leaks etc. But if anyone has any other ideas, they would be greatly appreciated..

Thanks.

I don't know if the td4 turbo setup is like my Lseries .I had a similar problem and it turned out to be a fault with the MAP sensor (Manifold Absolute Pressure ) .I ended up picking one up from a breakers for free .Instant fix .

One thing to look at is the cat starting to block up. We had one that was driving us crazy, changed most sensors, use a cleaner for the turbo all to no avail. Still getting a turbo boost fault. Dropped the cat off knocked the guts out of it and refit. Problem solved it had also had 2 tests since with no problem. Even if it is not the problem decatting it will make it run better anyway and its a job that will only cost your time.

Thank's for the ideas. Strange as it may seem, I'd never thought of either of them as possible causes. yet either of them gunging up with tarry toot could cause the problem. I think I'll pull the MAP sensor tomorrow, and give it a good clean, as that's the easiest to get to, and the inlet manifold is probably up to the paps. Thanks to the EGR....

The turbo itself may well be working perfectly OK...

simonmcghie said:

I think I'll pull the MAP sensor tomorrow, and give it a good clean, as that's the easiest to get to, and the inlet manifold is probably up to the paps. .

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I tried everything to try and clean my MAP sensor,nothing worked . I think it had got contaminated with oil .
Get someone to watch the dash while you twiddle the connector , you might find that could get the mil on or off .

OldIrishWulf said:

I tried everything to try and clean my MAP sensor,nothing worked . I think it had got contaminated with oil .
Get someone to watch the dash while you twiddle the connector , you might find that could get the mil on or off .

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Good plan, thank's, I'll try giving that a whirl as well.

simonmcghie said:

Good plan, thank's, I'll try giving that a whirl as well.

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I went out and bought a few different sensors before I got ,for free ,a MAP sensor with a broken inlet stem (fixed it with pipe and body filler)from a breakers yard . You might be able to try before you buy .

MAP can do it, as can blocked cat, leaky vac pipes, sticky solenoids, turbo pipes delaminating and blocking, turbo itself. You don't say if the fault was over boost or something else? Is the turbo control solenoid the same as another one on it? Egr possibly! If there's another one, Swap it, if it's faulty your fault will move to another system.

Thanks for the pointers, everyone.

A friend who runs a garage, and specialises in performance tuning has suggested a sooted up cat may well be the cause. (Probably caused by running with a faulty thermostat for quite some time.) As it mil lamp is still very intermitent, it's proving difficult to trace the exact cause. He recommended a product called 'Cataclean', which is added to the fuel tank, and it de-carbs the cat, egr, and turbo vanes. A bit like an industrial strength injector cleaner, which aslo cleans the exhaust gas passes. At £14 a bottle, I thought it worth a go.

Has anyone else tried it?

simonmcghie said:

Thanks for the pointers, everyone.

A friend who runs a garage, and specialises in performance tuning has suggested a sooted up cat may well be the cause. (Probably caused by running with a faulty thermostat for quite some time.) As it mil lamp is still very intermitent, it's proving difficult to trace the exact cause. He recommended a product called 'Cataclean', which is added to the fuel tank, and it de-carbs the cat, egr, and turbo vanes. A bit like an industrial strength injector cleaner, which aslo cleans the exhaust gas passes. At £14 a bottle, I thought it worth a go.

Has anyone else tried it?

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No! But I have only heard good things about it