Boost Question!

Hi all, you probably know that i am awaiting my HLM304 map so i am doing my Stage 0 tune:

Done the plugs ,leads, cap, rotor arm, modified the Air filter box with standard filter, all new hose on the turbo and all large hose cleaned and tightened up. I set the base boost on the actuator to 5lbs instead of 4.5 to make sure the door was shut!

So i should be ready for a surprise but i had a surprise today as the boost was down to 6psi with my air bleed type MBC on so i changed it for a brand new proper MBC and it was still the same 6psi

I took off the MBC and plugged back in the standard BCS and Whoa! what a difference, it boosted gradually then suddenly 15psi and immediately dropped to 10psi which i expect is the ECU taking over to safely cut it down, but it did not feel like hitting the proverbial brick wall i have had with the 940 turbo`s, is this a normal feel or should it be instant cut instead of gradual?

Has anyone experienced similar?

At least i have some sort of feeling of 15psi for when i fit the new 304 map!

Any ideas? or just normal......

is it boosting to 15 psi everytime you drive it? if so you need to wind your actuator back in a little

Hi Keith. It sounds like your MBC is set to minimum thus running actuator pressure only. The reason the BCS spikes to 15psi is because you adjusted the wastegate and the ECU is now reigning it in via the BCS to compensate for the extra preload on the actuator.

BTW you will know when you hit fuel cut, you will feel like you're going through the windscreen.

Quote:

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Originally Posted by t5frankie

is it boosting to 15 psi everytime you drive it? if so you need to wind your actuator back in a little

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I knew you would say that Frankie!!!

when i was setting it, it involved two complete turns from where it was set ,i could see the hole slightly elongated on the actuator arm so i did one turn and thought sod it give it one for luck, so it is too much, have to take off that wretched heat shield again, that timing end bolt is a large "B"

The overlap of the hole in the actuator arm is exactly on the edge of the large wastegate pin before fitting it back on so only just about 3mm tension on the diaphragm spring from recommended!

Quote:

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Originally Posted by mitchyboy01

Hi Keith. It sounds like your MBC is set to minimum thus running actuator pressure only. The reason the BCS spikes to 15psi is because you adjusted the wastegate and the ECU is now reigning it in via the BCS to compensate for the extra preload on the actuator.

BTW you will know when you hit fuel cut, you will feel like you're going through the windscreen.

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As i said to Frankie i will turn the actuator arm down a bit ,but just one turn ,would it make that much difference with the T5 as i had 5 turns on the T4?
Should i wait until the new map is fitted or should i just do it down 1 turn?

What do you reckon Mitch?

Keith

don't bother putting the heat shield back on

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Originally Posted by 960kg

I knew you would say that Frankie!!!

when i was setting it, it involved two complete turns from where it was set ,i could see the hole slightly elongated on the actuator arm so i did one turn and thought sod it give it one for luck, so it is too much, have to take off that wretched heat shield again, that timing end bolt is a large "B"

The overlap of the hole in the actuator arm is exactly on the edge of the large wastegate pin before fitting it back on so only just about 3mm tension on the diaphragm spring from recommended!




As i said to Frankie i will turn the actuator arm down a bit ,but just one turn ,would it make that much difference with the T5 as i had 5 turns on the T4?
Should i wait until the new map is fitted or should i just do it down 1 turn?

What do you reckon Mitch?

Keith

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the boost needs to be at 10 psi standard mate so keep fiddling around until you get it to where its supposed to be, leave the bcs in and dont worry about the mbc yet until everything else is sorted, see where the new ecu boosts to from the standard setting you have adjusted it to, once you are happy and want a little more whack the mbc on (i wouldnt reccommend a cheap one)and turn it up a little more, but boost will come in earlier at the expense of top end boost but you will be risking breaking something with early boost, i myself wont go over 10 psi until after 4000rpms

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Originally Posted by claymore

don't bother putting the heat shield back on

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Thank you for that, really helpful.

Quote:

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Originally Posted by t5frankie

the boost needs to be at 10 psi standard mate so keep fiddling around until you get it to where its supposed to be, leave the bcs in and dont worry about the mbc yet until everything else is sorted, see where the new ecu boosts to from the standard setting you have adjusted it to, once you are happy and want a little more whack the mbc on (i wouldnt reccommend a cheap one)and turn it up a little more, but boost will come in earlier at the expense of top end boost but you will be risking breaking something with early boost, i myself wont go over 10 psi until after 4000rpms

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Thanks both for your very valued help.

So can i really leave this wretched heat shield off for normal road use????

Keith

Quote:

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Originally Posted by 960kg

Thanks both for your very valued help.

So can i really leave this wretched heat shield off for normal road use????

Keith

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dont put it back on mate proper pain in the neck and you can make adjustments much easier if its off

Hi mate. What I would do is set it to standard, install the map and see where the boost sits. I think an HLM map will see around 16psi if all is well. If it is still a bit low put a bit more preload on the actuator. Then I would take it to the dyno and get a power run and check the AFRs. There may even be scope for a few more psi within the map and the AFRs may still be fine. This is where you need you're MBC on so you and the operator can do minor tweaks to the boost without having to keep playing with actuator.

Quote:

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Originally Posted by t5frankie

dont put it back on mate proper pain in the neck and you can make adjustments much easier if its off

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Thanks for that ,i just wanted to be sure i didn`t wanna cook my brake fluid!!!!

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Originally Posted by mitchyboy01

Hi mate. What I would do is set it to standard, install the map and see where the boost sits. I think an HLM map will see around 16psi if all is well. If it is still a bit low put a bit more preload on the actuator. Then I would take it to the dyno and get a power run and check the AFRs. There may even be scope for a few more psi within the map and the AFRs may still be fine. This is where you need you're MBC on so you and the operator can do minor tweaks to the boost without having to keep playing with actuator.

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Okey, dokey, will do tomorrow and leave the shield off `till all sorted.


Keith

Quote:

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Originally Posted by mitchyboy01

Hi Keith. It sounds like your MBC is set to minimum thus running actuator pressure only. The reason the BCS spikes to 15psi is because you adjusted the wastegate and the ECU is now reigning it in via the BCS to compensate for the extra preload on the actuator.

BTW you will know when you hit fuel cut, you will feel like you're going through the windscreen.

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That happened to me when i had a mbc thought i had broken something when it first happened,you know that sinking feeling/heart pounding moment when you think its about to break down and stop..

I still got my heatshield off from when i did my dyno run last weekend as i said to the mechanics there to leave off in case my actuator needed replacing or adjusting,remember when you are going along the air flow underbonnet will push a lot of the hot air away and once its all set up nicely you can then replace the heatshield not forgetting a bit of coppaslip or the threads