Morning everyone I have installed a boost gauge and put the tee in the hose going to the waste gate now I know the truck has a map on it from mastraz which was already on it it pulls really well boost is reading on the gauge between 24-28 psi is this too much and how much drop in boost will I get from the turbo to the inlet manifold if any thanks.
Discovery td5 boost
- Thread starter TD5Tom
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sierrafery
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Hi. Do you have a boost box or the remap is together with an uprated MAP sensor? without one of these you cant get such boost cos the overboost limit is at 20.5 psi. The boost at the wastegate should be quite the same like at the manifold
I asked the previous owner who told me the mapper removed the overboost but I know it hasn’t had a updated map sensor but it does seem to be boosting high on the gauge
sierrafery
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Overboost "removed" without an uprated MAP is some kind of bodge cos the standard MAP sensor can read just untill 1.5 bar(21.75 psi) boost, what's above that is not calculated so i dont know how is your setup, if that's what you get with the gauge then that's it, how many threads are left back from the wastegate's locknut ?
There are roughly 7 threads left and I’m not sure about all the sensors but the gauge definitely goes past 25psi so would the map sensor restrict the boost?
sierrafery
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At 7 threads left that 25+ reading is normal. As long as the overboost limit is raised in the fuel map the MAP sensor will not limit anything just that above 21.75 real boost the ECU will not know it cos it will get only the MAP's maximum output so the fuelling calculatios are mixed up exactly like with a boost box
Is this likely to damage anything
EeEk
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I thought disco td5 turbo wastegates were vaccum?
If you tee'd in to the pipe going to the wastegate....is it boost of vacuum you are seeing?
If you tee'd in to the pipe going to the wastegate....is it boost of vacuum you are seeing?
I am unsure
EeEk
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The engine control module controls the amount of boost pressure the engine receives by way of the turbocharger.
When full boost is reached a control signal is sent to the wastegate modulator, and a vacuum is applied to the
wastegate valve. The wastegate valve opens, bypassing some of the exhaust gas away from the turbine to be output
to the exhaust system.
Oh right so I need to adjust the boost and lower it
EeEk
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Id say you have to connect your boost gauge to boost source and not to a vacuum source
Well I have the tee for the boost gauge in between the boost control module and the intake pipe that comes off the bottom hose from the turbo I prosume that will be reading boost going to the module
EeEk
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You could well be right.....I know vaccum has something to do with controlling the turbo but how its plumbed in ???
I don’t know all I do know is that it definitely plumbed In to the boost so I think it needs lowering as I don’t know how much td5 can take before something will brake
sierrafery
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That's how it's described in the WSM but it's wrong which becomes obvious once you check how it is in reality, it's boost off course and as i said first time the pressure you see there should be very close to what's at the manifold as long as there's no leak or restriction on the way.
Will this much boost raise egt and or damage anything
sierrafery
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It depends on how the fuel map is configured it can affect EGT or not, you'll have to fit a gauge, there are Td5s running on 25+ psi boost but those are tuned especially for that(stage 3, big intercooler, free flow exhaust, etc), without proper tunig that boost is a bit high IMO
sierrafery
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set back the wastegate to 9 threads and you'll be OK
