Thread: Injector Pump Tweek, just a Little

Hi Andrew,

If it's just a bit more grunt on initial take-off you want, then a simple adjustment of the stop screw should do the trick. No need to open the diaphragm cover at all.

Prise out the thin steel cover in the top of the diaphragm cover using two fine screw driver blades (cheap jewellers screwdriver sets are ideal). Now get yourself a T-27 Torx bit (or an Allen key that's a good firm fit into the Torx screw head) and a 13mm socket. A bit of WD40 on the Torx screw and 13mm locknut will probably help.

Crack the locknut loose and, being careful that the Torx screw doesn't move, back the locknut off one and 1/2 full turns. Next turn the Torx screw in (clockwise) 1 & 1/2 turns then nip up the locknut. Now go for a drive and repeatedly stop and take-off again from a standstill. You should feel a noticable improvement in initial take-off, and a bit more initial smoke perhaps. If the smoke is minimal, try another half turn 'in' on the Torx screw until you find an acceptable compromise between smoke and 'launch' performance.

It's impossible to say which way (CW or CCW) to begin rotating the diaphragm if you going to do the 'full' tuning. It all depends on where it was assembled in your particular pump at the Bosch factory. Contact me directly if you'd like me to clarify anything in the Tuning Notes. Hope this helps.

Originally Posted by Leo109

Hi Andrew,

If it's just a bit more grunt on initial take-off you want, then a simple adjustment of the stop screw should do the trick. No need to open the diaphragm cover at all.

Prise out the thin steel cover in the top of the diaphragm cover using two fine screw driver blades (cheap jewellers screwdriver sets are ideal). Now get yourself a T-27 Torx bit (or an Allen key that's a good firm fit into the Torx screw head) and a 13mm socket. A bit of WD40 on the Torx screw and 13mm locknut will probably help.

Crack the locknut loose and, being careful that the Torx screw doesn't move, back the locknut off one and 1/2 full turns. Next turn the Torx screw in (clockwise) 1 & 1/2 turns then nip up the locknut. Now go for a drive and repeatedly stop and take-off again from a standstill. You should feel a noticable improvement in initial take-off, and a bit more initial smoke perhaps. If the smoke is minimal, try another half turn 'in' on the Torx screw until you find an acceptable compromise between smoke and 'launch' performance.

It's impossible to say which way (CW or CCW) to begin rotating the diaphragm if you going to do the 'full' tuning. It all depends on where it was assembled in your particular pump at the Bosch factory. Contact me directly if you'd like me to clarify anything in the Tuning Notes. Hope this helps.

Great thanks Ian,
Ive had a look and noted that the mark on the dia was at between 6-7 oclock.......so Im not sure weather I should move it at this point.....can I stuff anything up?

Also there was a heap of black greasy crap on the cone....

Ive moved the dia 90dec (from say 7 oclock to 10) and Just took Disco for a drive, Im surprised what the little ajustment has made , blows a little more smoke with hard throttle, but its much more nippyer now

Now by doing this will it affect the EGT at all?

Anyother probs to worry about?

Hi Andrew,

"can I stuff anything up?" well, I don't know about you, but I can stuff anything up if I put my mind to it!

Seriously though, no you can't really stuf much up as long as you have noted the original position of the diaphragm and can return it to that point if things don't go as planned.

If you were to rotate it, say, 60 deg in either direction then you should notice either (a) improved performance (if you've actually increased the fuelling by the adjustment) or (b) decreased performance (if you've decreased the fuelling by the adjustment). If performance has decreased, then put it back to the original position and then move it 60 deg in the other direction.

But it's much better to understand from the outset exactly what you are doing and how it works. I've been meaning to draw some better diagrams to explain the diaphragm/control cone thingies for a while now. If I finally get my A into G, I'll send them to you.

Not sure what the "heap of black greasy crap on the cone" is. The ones I've looked at have just a light coating of a brownish grease. Has the vehicle ever been 'parked' in very deep water (i.e. up to the diaphragm) to your knowledge?

Originally Posted by Leo109

Hi Andrew,

"can I stuff anything up?" well, I don't know about you, but I can stuff anything up if I put my mind to it!

Seriously though, no you can't really stuf much up as long as you have noted the original position of the diaphragm and can return it to that point if things don't go as planned.

If you were to rotate it, say, 60 deg in either direction then you should notice either (a) improved performance (if you've actually increased the fuelling by the adjustment) or (b) decreased performance (if you've decreased the fuelling by the adjustment). If performance has decreased, then put it back to the original position and then move it 60 deg in the other direction.

But it's much better to understand from the outset exactly what you are doing and how it works. I've been meaning to draw some better diagrams to explain the diaphragm/control cone thingies for a while now. If I finally get my A into G, I'll send them to you.

Not sure what the "heap of black greasy crap on the cone" is. The ones I've looked at have just a light coating of a brownish grease. Has the vehicle ever been 'parked' in very deep water (i.e. up to the diaphragm) to your knowledge?

Im happy with the take off now, not sure about the smoke though, but if Im just sitting there and then take off foot hard to the floor, after abut 20m down the road I look back and see a bit of a clould of black smoke, but cant see much when driving....... I might back it off a tad and see the diff.

Ok so all Ive done is just ajusted the amount of fuel that can be used if needed?

So will it affect EGT at all? Use much more fuel do you think?

Hi Andrew

If you remember the original position of all the adjustments its possible to revert back and nothing is really stuffed up. My fuel consumption increased on the trip up to Rutherglen because I was more or less driving like a bat out of hell, it was around 12L/100km. On the way back I was being normal / sensible and it returned to just under 10.

An EGT is a wise idea if you go into the diaphragm casing, especially if you turn the starwheel. I bought mine from Auber Instruments in the US, with a K-type thermocouple and with shipping it was $88.50. Not bad considering the 250 odd for VDO ones.

http://auberins.com/index.php'main_p...products_id=19

A normal diesel type haze is fine, even a bit of black smoke under full throttle, but if its putting out a sooty cloud it might be a little too much.

I'd recommend the EGT though, if you have a EGR blanking plate on your exhaust manifold it will take 3.5 seconds* to install.

*slightly exaggerated.