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Tune / brake booster

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Hey I have a 1uz Lexus v8 with itb's and since the vacuum created from itb's is terrible, would the (diagram attached) be the proper plumbing? I assume it would work but would this affect my tune since it would be tied into my map line? Or is there another way of doing this? The itb's have equal length 1/8" lines to a 8-1 collector and then they go to map sensor in the ECU. That is the only vacuum ports.

Thanks Dan

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Even with the marginal vacuum signal from itb's, you should still have no problem running a brake booster off them. Most OE multi-throttle setups have a dedicated location for your brake booster vac signal and this runs off a balance bar from all the throttle bodies. The part you may be missing is that it's essential to have a one way valve in the vac hose to the brake booster. This means that there is sufficient vacuum stored in the booster during times of high manifold vacuum to give good brake assistance even at WOT when there is no vacuum in the manifold/itb's.

I wouldn't recommend sharing the vac signal between the brake booster and the MAP sensor though. I've never done it but I can imagine the MAP signal being affected when you're on and off the brakes. On that note though, I'd also advise you to use TPS as your load input rather than MAP (unsure at this stage what the MAP sensor is doing in your installation).

I have the map lines hooked up to the ECU via. 8-1 collector, but i am using tps and rpm as load inputs. I am new to the self tuning and just didn't know if this would affect anything.

As for a designated lines for the brake booster there is also 4 ports at each "corner" of the throttles, my assumption is that this is probably the line for brake booster.

Besides missing a check valve at the brake booster too, all the other plumbing looks right? Is there a reason why I should have a vacuum pump and storage canister?

Thanks again for your help.


Vacuum pumps and accumulators are typically necessary in engines that don't produce enough vacuum for the brake booster to function - Diesel engines for example with no throttle body would be a great example. Unless you fall into that category then no, a vacuum pump shouldn't be required.