TD5 Overboosting Defender

Hi guys,

I have got a misfire at high revs on my 90, and im chasing the problem all over the place, ive landed at overboosting because after i ran the engine with the turbo actuator off it stopped the misfire making me belive it doesnt work. So ive had it tested and apparently the actuator works perfectly, what else could be causing the problem? any ideas or can i just readjust the actuator arm to suit it running nicely?

I'm looking into something similar at the moment. Have you checked the MAP sensor? I had mine out and cleaned it last week and i'm now convinced that it was, and possibly still is giving faulty readings. Also if you can get your hands on a boost guage, you can get an actual reading. If the boost gauge shows good reading (up to 20 psi?) then it could be a faulty pressure sensor.

Unless you have modified the boost pressure signal to the ECU anything more than 1 Bar on a TD5 will cause an overboost error and the ECU will go to limp mode until restarted.
You can adjust the actuator arm until it runs well. Making the arm longer will turn the boost down as the wastegate will open earlier.

only diagnostic can tell you if map is fooked if it runs manifold presure 98.5kpa then map sensor is dead and running on defualt 101 upwards is ok .
i chased a similar problem on myne changing many parts that wernt at fault over the last year ,trust me diag print out will tell you alot of info and people on here can compare wished i did it a year ago and saved a lot of cash on needeless bits

ive adjusted the arm and now its perfect, it diddnt help my manifold was warped by 4mm! though, thanks for all the help

defender1990 said:

ive adjusted the arm and now its perfect, it diddnt help my manifold was warped by 4mm! though, thanks for all the help

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Just resurrecting this thread... Having the exact same issue. I've disconnected the MAF sensor and it made no difference so then I adjusted the actuator arm and it's making little difference that I can tell. Still choking at high revs. (pulls like a train until it get there).

How many turns of the actuator knob and which way do you think I would need. Is it tiny adjustments or multiple turns? Any help greatly appreciated.

https://ibb.co/vc8c0rc