Idle cant go low enough!? toyota 5L-T

[ajthompson]

Hey guys,
I recently finished my project, and now i have a turbo'd toyota 5L.
she's got a shite load of grunt and torque now
(will post thread with photos soon)

anyway long story short, i had the pump rebuilt, and had the top half of a 2LT pump put on, so its got a boost compensator.
I had it running low boost first to try out and the pump works really well, i can turn the fuel up without it being smokey at idle.

now I've got the turbo running at higher boost and the fuel had to go up more. i have the idle as low as it can possibly go, but its not low enough
where the throttle linkage meets the pump theres also an adjustment, but that is also adjusted as low as it can go.

anybody got any tricks to adjust my idle further?

[zukmeista]

Wind the max fuel screw out.

[ajthompson]

ideally i want to turn that up a tad more to get an ideal air/fuel ratio. ive had it idling good already by backing that screw off, but it was running too lean.

[zukmeista]

Not sure what the toyota pumps are like but here is a how-to video on tweaking a Daihatsu pump.
http://www.youtube.com/watch?v=n3MTJz0msKU

[ajthompson]

thanks! that video was helpful, i might try adjust the pre load on the boost compensator and see how it runs

[tweake]

adjusting preload on the comp won't help.
all thats happened is you have the pump maxed out. need to go get a bigger plunger installed.
in the mean time just back off the fuel screw to drop the idle back down.

the fuel screw changes the start point of the injection, which is why idle changes when you adjust it, while the boost comp controls the end point. so adjusting boost comp won't change the idle.

[ajthompson]

i think i might still need to give the boost comp a fiddle. at the moment it blows a little black smoke if i floor it from idle with no boost (which is probly perfect) but the top end wants more fuel.
but yea maybe a larger plunger is on the horizon then

[tweake]

normally you would tweak the boost comp to get rid of off boost smoke. just remember it doesn't give any more fuel to the top end.
in this case winding off the fuel screw to correct your idle will also fix that off boost smoke.
downside is you will reduce overall fueling and loose power.
time for a new IP

[ajthompson]

ok thanks, that makes things clear. guess ill leave the boost comp alone. and yea i might just have to put up with a little less power for now

[ajthompson]

I did a bit of research on boost compensators. Found this thread which had a lot of useful info.

http://toyotasurf.asn.au/forum/viewtopic.php?p=121314

Further down the thread there's a good pic of a modified metering rod. I might try the same seeing as I can afford to turn the non-boost fuel down a bit.

It's also useful to know that there's two ways of getting better boost compensator response:

1. Widen the hole on the boost comp lid and get a larger diameter hose on to it. This will get more air in the lid faster.

2. Fill any hollows on inside the lid with epoxy. Keep layering it and shape it so its smooth. The smaller the space in the lid, the quicker it will fill with air.

I'll try both of those down the track. From what I've read people get good results from doing those mods, making turbo kick in harder and faster