Club 80-90 Forums

Been trying to locate the lack of power in my JX. The LDA diaphragm was knackered and so this has been replaced. We've had the LDA on a compressor and it 'opens' at about 0.25 bar, but whilst the van is running around with a boost gauge on the tube to the LDA, we can only get 0.17 bar (albeit on a local loop rather than big hills). So the LDA isn't opening, we're not getting extra fuel, and so struggling with power.

Have tried: checking the turbine in the turbo, with a finger in and rotating the turbine it feels pretty free, perhaps some roughness at one point but nothing drastic. Have tried winding the waste gate screw in a turn but that hasn't made a difference. No air is coming out of the blow-off valve.

Any ideas on what to try next before taking the turbo out and replacing? Can you check the wastegate if you take it out and have a compressor and pressure sensor to hand? Anything else we should be looking at?
Many thanks
 

Forgive me for being obvious but have you replaced the vacuum hose (yes i know its not vaccum but boost pressure ) as i have just rebuilt my Lda with the kit available) as my diaphram had also gone. Chances are it may have also failed

Ill check mine tomorrow morning and see what pressure mine opens at

i assume you mean the pipe from the LDA to the inlet manifold. yes we've checked that it's clear and not leaking. What's weird is that it will get 0.17 bar as we drive around (which would suggest no major leaks) but just not getting enough oomph from the turbo.
 

what rpm arent you getting boost, how high are you taking the revs?

i don't know, there's no rev counter on mine!
I can see the boost pressure rising on my gauge, but it maxes out at 0.17 bar, which isn't enough to open the LDA. Do you think that my local run (working it as hard as I can) isn't enough to call for sufficient boost?

 

i've seen a video where the LDA opens just on revving under no load https://www.youtube.com/watch?v=i3jtM60Eyxo . Mine definitely doesn't do this!
 

the JX is a relatively low boost system. 
The LDA lever should move to the most extended position at 0.6bar. 
The original system has a blow off valve on the intake manifold. It lets overboost either to atmosphere or to the intake manifold depending the year. That could be set up incorrectly.
You should check the hose from the turbo to the inlet manifold for leaks too.

Your wastegate also can be stuck open. you can check it with a boroscope from the exhaust side.