adjust fuel enrichment

[rett]

evening all
am hoping one someone here night be able to give me the heads up on this on

an ongoing one here. my jx 1.6td, motor smokes more than i like when the turbo kicks in, i only really see this at night tbh when its getting highlighted by lights behind.
today with a bit of help from a mate we adjusted the nut on the rod linkage from the lda to the pump.

the thought behind this is to reduce/limit fuel intake and get air/fuel ratio right. and an hopefully sort out the smoke when the foot goes to the floor.

the test drive was interesting ,alot more responsive at least by 10 percent , still pushing smoke over 3000 rpm thou but not as much as before.

Do i carry on with minor adjustment of the nut ?

any thoughts on this would be appreciated

thanks in advance


recon unit/injectors /turbo last year/new air an fuel filter/ tappets ok/all timing good.

[MGP]

The lda works the other way around as in it limits off boost fuel and on a JX pump it's at max fueling by around 5 psi.
If you have black smoke at full boost then either someone has played with the max fueling screw of you are not making enough boost pressure.
A light haze is acceptable and if you can only see it at night against the headlights of cars behind its normal with an idi engine.

[greasemonkey]

The lda works the other way around as in it limits off boost fuel

Surely it richens on-boost fueling, than limits off boost.

In its 'passive' state the LDA is not doing anything, and only operates when pressurised from the turbo which in turn triggers the additional fueling for boost power.

I.e if you're not making enough boost, the LDA won't be fully operating since its directly triggered by the psi from the turbo, so you can't be over rich with less boost unless the fueling mechanism itself has been messed with.

[MGP]

Sorry didn't explain myself very well. The max fueling is set via the max fuel screw and is adjusted for fueling at max boost. The lda is adjusted to limit delivered fuel in off boost conditions and also how fuel is increased with boost so the lda mechanism inside the pump is working at its maximum off boost and doing nothing at full boost.
The problem with the jx lda is that the spring inside the canister is maxed out at about 5 psi so if someone has set the boost to say 14 psi and the fueling to match and now it's only making 10 psi for whatever reason the it will be over fueling because the lda is still allowing full enrichment.

[greasemonkey]

Gotcha.

[rett]

hi mpg
cheers for your comprehensive reply.
my logic was the same as grease monkey, but he explained it better.
any idear on the increase performance of the van by my adjustment i made ? ( restricting how far the threaded bar can travel )
i haven't touched the fuel screw as the van ticks over fine and is generally a good runner (although a bit sluggish or was )
the psi hasn't been checked on the new unit ,so will get that done.

[MGP]

It's been a while since I had a JX pump apart but I think I recall seeing that the lda setup can go over maximum and start restricting again due to the way it's laid over to fit under the engine hatch.

[rett]

hi mp just thinking about what you mentioned about boost and over fuelling. i do have a issue as well with the smell of unburnt diesel on idling . so i need to get boost checked i suppose
i think it needs to have visit to a decent shop.

[MGP]

Do you know what the pump was actually timed to?

[rett]

hi mp

since last post had pump timed timed at a reputable shop
started it next day ran like "pooh" and smoked the street out(,sometimes i really wonder)
its back in tmz to get checked an have a leaking injector looked at.
I need to get more hands on i think

[MGP]

Did they say what they had timed it to? It sounds like it needs advancing slightly.
Did you pull the cold start out?
It does sound like now might be a good time for you to buy yourself an adaptor and a dti.