Suddenly, Im a boy racer........

[BUSHWHACKER]

On a 2.4, I think this might be a pertinent point if you're going for a leaner mix:

http://forums.hypography.com/chemist...e-run-hot.html

In short, leaner mix = more total combustion = better running but with more heat = be careful messing with that screw.

I think it has the opposite affect with diesels though.

[Sancho]

so you think I should turn it back up a bit?

I don't know, I just make this stuff up.

[Billy-No-Money]

I think it has the opposite affect with diesels though.

So I cant overlean it then?

[Billy-No-Money]

Mind you, am i actually adjusting the combustable fuel/air mix? Isnt that all adjusted on the throttle body?

[BUSHWHACKER]

So I cant overlean it then?

Well, the ECU would have something to say about it first, by means of the red engine check light on the speedo face.

[Billy-No-Money]

Im getting no warning lights, so its probably a case of 'so far,so good' Might be safe to quit while Im ahead, though the prospect of squeezing yet a few more MPG is tempting.....

[TonyN]

Well, the ECU would have something to say about it first, by means of the red engine check light on the speedo face.

There is no oxygen sensor in the exhaust, the ECU has no idea how lean/rich the motor is running.

[POPEYE]

Right! So whats the verdict then, clockwise or anti- i'm confrickinfused all over again now, i turned mine CLOCKWISE just under quarter turn and the truck is definatly better, was going to try another quarter and see

[Billy-No-Money]

There is no oxygen sensor in the exhaust, the ECU has no idea how lean/rich the motor is running.

Just so I know, am i correct in thinking that the only job of the pump is to keep sufficient fuel pressure in the injector rails and that the ECU, dependant on varius sensors, governs the injectors to deliver the correct ammount of fuel for the relevant throttle position? Are these engines direct injection and no carburettion takes place prior to ignition? There fore by turning down the available fuel flow through the pump I am in fact simply reducing the available pressure within the fuel rail and the ECU will not know thw difference so that when it fires the timed injection it thinks that it firing more fuel in than it actually is?

[TonyN]

Right! So whats the verdict then

You're screwed, sell it now, quickly....

[MattF]

Just so I know, am i correct in thinking that the only job of the pump is to keep sufficient fuel pressure in the injector rails and that the ECU, dependant on varius sensors, governs the injectors to deliver the correct ammount of fuel for the relevant throttle position? Are these engines direct injection and no carburettion takes place prior to ignition? There fore by turning down the available fuel flow through the pump I am in fact simply reducing the available pressure within the fuel rail and the ECU will not know thw difference so that when it fires the timed injection it thinks that it firing more fuel in than it actually is?

You're altering the amount of fuel delivered. Do you want truthful advice or put your mind at ease advice?

[TonyN]

Indirect injection. yup, the ECU assumes the right amount of fuel is going in, as its set up at the factory. It moniters fuel pressure, air/engine/fuel temp etc, and can adjust things for optimum running.

Not sure what you've done, but normally deisel tuning is simple, add more diesel untill it starts making to much smoke. which is why most people richen the mixture, till the smoke is to bad, then you need to get more air in, as the valve timimg is unadjustable, intercooling for a denser air mixture, or increasing turbo pressure to shovel more air in are the only easy options.

A jammed open injector will burn a hole in the piston (ask Snoop! ), so to much fuel can be a bad thing.

Just so I know, am i correct in thinking that the only job of the pump is to keep sufficient fuel pressure in the injector rails and that the ECU, dependant on varius sensors, governs the injectors to deliver the correct ammount of fuel for the relevant throttle position? Are these engines direct injection and no carburettion takes place prior to ignition? There fore by turning down the available fuel flow through the pump I am in fact simply reducing the available pressure within the fuel rail and the ECU will not know thw difference so that when it fires the timed injection it thinks that it firing more fuel in than it actually is?

[Sancho]

All I'm saying is that from the sounds of things, turning the screw one way makes the mixture rich (hence the smoke) and the other way makes it lean. Maybe running a richer mix compensates for old injectors (by putting more pressure through a smaller hole = same amount of fuel) so all people are actually doing when running it richer is returning it to a bit more like how it was when it came out of the factory.

Diesels do like to be hot so maybe it is not possible to overlean them as a general rule, but the 2.4s suffer from heat-related problems in the head so I would have thought doing anything to make them run hotter would be a bad idea.

I don't know anything about this, but I wouldn't personally start fiddling with anything that Mr Toyota had worked out on his computer.

[Darren]

An RAC mechanic once told me that japanese diesel has different octane levels and that adjusting the fuel pump to allow for UK levels would make Surfs run better, I think our diesel had more octane. I'm no expert but if UK diesel is stronger stuff then maybe making the surf run slightly leaner would account for this. Just my thoughts
Darren

[Billy-No-Money]

You're altering the amount of fuel delivered. Do you want truthful advice or put your mind at ease advice?

Just want to know what Ive done and if its good, bad or unimportant. Isnt there a benchmark setting for the pump adjuster screw like there is on the mixture adjustment of a carburettor? You know, screwed fully home then out by X number of turns then fine adjustment from there? That way I could figure out whether someone before me had altered it ( its 14 years old and the thimble cover popped off like it was new) and could re-set it to where it should be and go from there.