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Is it possible to adjust boost compensator

Tech Talk for Cruiser owners.

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Posts: 292
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Is it possible to adjust boost compensator

Post by hilux79 »

Hi I’m trying to find out if it is possible and if so how hard it is to adjust the boost compensator on my 3L hilux. I’ve wound the fuel down as my EGT’s were to high on boost but now it is a bit of a pig off boost.

My understanding of a boost compensator is that it limits fuel off boost to stop over fuelling. So if I can reduce this limiting factor I should get some low-end power back.
Ben
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Location: Towsnville

Post by Mattoz »

is you pump modified?

the standard 3l pump does not have a boost compensator but to my understanding you can fit one off a 2lt pump to the top of a 3l pump
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Post by hilux79 »

Yeah mine has had the 2lt compensator fitted.
Ben
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Location: newzealand

Post by tweak'e »

something sounds odd.

if you have wound it back that much its effecting off boost perforamce (which means on boost performance must really suck) the boost comp is no longer doing anything.

what was the temps? measured where?
what did you adjust on the pump?
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Post by hilux79 »

tweak'e wrote:something sounds odd.

if you have wound it back that much its effecting off boost perforamce (which means on boost performance must really suck) the boost comp is no longer doing anything.

what was the temps? measured where?
what did you adjust on the pump?
On boost it is still good. I pulled the boost compensator apart today and i think the metering rod was a bit sticky. I found a good link that explains how to adjust the rod and I will have a play with it tomorrow and see what difference I can get. The link is http://dahn.webcity.com.au/~toy49040/fo ... php?t=8972.

My temps are post turbo and on a long hill will go past 500 I back off before they go any further so not sure what they would peek at.

The fuel screw on the back of the pump is the one I have wound out. Pretty sure it is the right one as it makes a difference and is the one pointed out by the guy who did my injectors to adjust.
Ben
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Post by 80diesel4play »

In short yes you can adjust it. I'd get a diesel tuner to do the work as if you f%$k it up you will be at the diesel guys emptying your wallet...

Easier to do it right the first time and get a warranty... and the emptied wallet!
80 Series Turbo - the Toy car...
XR6 Turbo - the work car...
XW wagon - the dogs car...
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Post by tweak'e »

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Location: Perth, Australia

Post by BIG12HT »

Hi, you have adjusted the main fuel screw, which means everything is affected and as you are noticing, the off boost fueling has been reduced. 0.5 turn = 20% either way, so bear that in mind. Anticlockwise 1/2 turn = 20% less, vice versa.

Rather than lowering fuel to limit EGT, you might try a couple more psi boost. High EGT are caused for the most part by running rich, providing your turbo is stcok and boost is stock, a few more psi show make a signifuicnt difference to the EGT and also reduce your soke - you might even pick up a coupel of HP.

If you want to reduce the fuel on boost, you can rotate the aneroid rod to a different profile - at zero boost, the measuring pin is on the larger diameter of the aneroid piston so the less the pin can move, the less extra fuel it delivers.

If someone else has played with the pum in the past, I suggest the following procedure (Providing your injectors are OK).

* Disconnect your wastegate actuator
* Disconnect the pressure line to aneroid (just in case slight pressure)
* Adjust the aneroid preload on top of the aneroid to minimum depression - may need to take of cap and adjust it by eye. Put all back.
* adjust main fuel screw either way until, holding the revs at 1200 and stabbing the throttle, only mild smoke is noted.
* Drive the car from 1000-2000rpm and note the low end torque. If enough for off boost, leave it, if not (highly likely), increase slightly noting 0.5 turn = 20% extra fuel which is alot.
* Once happy, reconnect wastegate and aneroid boost hose
* test drive, check EGT and "come on boost" behaviour. If ok, you are done, if not then need to know problem. Here are some:

- EGT still high, blows smoke coming on boost
* turn the star wheel which controls the spring preload under the aneroid diaphram and turn anti clockwise. This will increase the boost requirement before extra fuel and bring on turbo a bit later, depending on how much you tighten it. Since it increases the pressure the boost is working against, depending on the aneroid piston position, it may affect maximum fuel and reduce the maximum providing you havent changed your boost setting. If it has, great, but if it has done this at the expense of a bit of lag, then you can either increase the preload setting for the aneroid pistion (screw on top of aneroid), or use a aneroid piston profile that is initially a steep ramp but hits alower max fueling level (ie: steep, but shallow). You may also reduce the star wheel controlled aneroid spring tension if you use a better profile to increase lower boost fueling.

- EGT OK, power under boost OK, poor boost response
* Injectors probably need a service, hence the no load smoke when revved with a stab on the throttle. Increase preload on aneroid until your optimum response is achieved. Possibly reduce star wheel aneroid preload to bring on a bit quicker. Main thing here though, is off boost fuel table

Anyway, theer are other scenarios, but hopefuilly you get an idea how the pump works from that.

Cheers, Graeme
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Post by BIG12HT »

Something you probably know, but you need to reset your idle speed after playing with the main screw.
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Post by hilux79 »

Thanks Graeme. That post is great.

I'm running 10psi un intercooled from a ct20 so think inlet temps will rise a fair bit if I increase boost more. I have rotated the rod to the less aggressive ramp and it has helped low down power to a point that I'm happy with. But I will follow your instructions and see if I can get a bit more.
Ben
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