Thread: Turbo/boost problems?

Full noise it struggles to push .7 bar of boost, according to the Nanocom.

That's very low, how many threads are left out from the wastegate actuator's rod? ... from factory there should be 13 threads from the locknut for 1.3 bar boost. A well working engine can accept 2 to 3 threads tighter before going to overboost but at so low boost i doubt it has much effect as the wastegate should start opening at around 1 bar so at 0.7 the actuator would not even move... make sure that the wastegate is not stuck open

IMO in your case it might be a boost leak, intake or exhaust restriction or fuelling issue... as already mentioned by mr @shack better save an "inputs fuelling" log on SD card as to catch some "full noise" moments and post it here

a simple check if you can afford some noise where you are would be to undo partially the exhaust downpipe from the turbo as to release some flow there and see how it goes that way cos a quite common issue on facelifts is clogged catalyst then the boost can't rise

you must fix it to run as it left the factory(at least 1.3 bar boost) before a remap otherwise you'll just "boost up" an existing issue

I've had a quick look, to my knowledge the modulator has not been changed. Are they a generic part, or Land Rover specific?
I'm getting various amounts of boost, today it was reading .9 and driving much better. Later the boost fell to .8. There is no missing/surging.

I'll post this video for anyone doing a search, in future.

The modulator can be bypassed by connecting a hose from the turbo outlet to the wastegate actuator to have base boost of 1 bar if the actuator is adjusted to factory specs. The 3rd hose to the modulator should be blocked.

Originally Posted by V8Ian

I've had a quick look, to my knowledge the modulator has not been changed. Are they a generic part, or Land Rover specific?
I'm getting various amounts of boost, today it was reading .9 and driving much better. Later the boost fell to .8. There is no missing/surging.

I'll post this video for anyone doing a search, in future.

Defenders don't have modulators, only the Disco Td5's.

The vid is showing ( and making a meal out of it ) him removing the actuator, not the modulator.

FWIW, I have not seen a modulator fail in this way, they have all failed by causing over boost.

You don't drill the rivets out unless the Bracket Bolt is seized ( or butchered previously )

10 seconds of time to remove the air box top and intake pipe would have made his life easier.

No need to undo the 10mm head lock nut on the actuator rod shaft either.

If your wastegate is stuck open you wont get the "surging" from ECU boost cut, just low performance.

The fault shown in the vid would have been from the wastegate being stuck partially closed.

I'm not saying this is definitely the problem, but that it could be. We'll wait for "Chook" to post a log.

When the modulator fails it usually creates overboost as nothing passes through it to the actuator, if you unplug it's electrical connector it should be like bypassed as it's N/O. When the ignition is turned on the modulator closes as no boost to be wasted untill 1 bar is reached then the ECU starts to deliver PWM pulses to open it as to manage an optimal boost curve untill the set limit which is adjustable with the threaded rod... Though as long as you don't get more than 1 bar boost the wastegate is no factor as long as it's not stuck open. Clamp the hose to the actuator and go for a ride then, it should go to overboost on first kickdown and if it doesnt the problem is not in that area but there is not enough boost for other reason(leak, restriction or fuelling)

I was going to drill the rivets and replace them with rivnuts, spring washers and bolts.

Originally Posted by V8Ian

I was going to drill the rivets and replace them with rivnuts, spring washers and bolts.

Yep, it'd work, I've only had dramas when the bracket bolt has been butchered, usually use a 10mm ratchet spanner and fingers get it out in seconds, but leave out the spring washers and use hex serrated flange bolts if you're going to Rivnut it.

Here's a link to one of the better videos on the modulator, runs through the how and why it operates, and then changes one. I'm not sure it's as important as he says for protecting the engine as my Defender Td5 seems to do ok without one.


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