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Tuned Isuzu 1.7td run out of idle adjustment

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Jan 16, 2012
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Hi everyone, I have a tuned isuzu engine in my mk3 estate... have done the white ring mod, free flowing exhaust, short intake pipe with big cone filter, upped boost to 1.5bar, front mount intercooler and NA inlet manifold, as well as some increase on the max fuel screw.

This has been done for quite some time now and when it's running good it flies!! However I've noticed that over time it seems to gradually drop off on the fueling and get steadily less powerful. After turning the max fuel screw up some more it is restored again and runs great!

My question is, what might be causing this gradual loss in fueling over time? Is there something in the pump which is slowly wearing out with the upped fuel and thus slowing flow over time?

My other problem is that having re-upped the max fuel screw a few times now, I am no longer able to lower the idle back to normal as travel on the idle screw is run out!

Any help and information would be appreciated, thanks!
 
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Regards the idle, mine doesn't actually sit back at the stop so I added a small spring to it to assist the throttle / idle return to the backstop. You can also try bending it slightly, im sure I also did?

Not sure on the power loss but maybe you have a slight boost leak? something else you could look at. Is it still boosting and holding the same as before?
 
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Thanks for your reply! I'm pretty sure it's past that stage for me, I think I have given it a bit of a push to bend it out the way before. The problem now is that the throttle is now resting on another adjustment screw on the fuel pump when idling (I don't know if this is a hot idle adjust or something else?) I'm reluctant to adjust it without knowing what it is.....

Boost is holding perfect at 1.5bar, so I'm pretty sure it's a fuel issue. Cheers
 

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