Fooling Boost CUT???

[merc85]

Hi there been fiddling after fitting a New Boost gauge and some how my 850 t5 Auto can over ride Boost cut?

When i Accelerate hard bit not Kick down and she reaches 15psi she boost cuts and the ecu try's to back it down to 11psi.

When this happens all i have to do is HIT the kick down, then she can keep 14psi.

Does anyone know how or why this happens?? for now i have backed the boost down to a Constant boost of 12.5psi with no probs.

[daveforber]

If it's only happened after you fitted the gauge, perhaps some of the lines are leaking or not secured properly? You could end up leaking some boost as per a bleed valve, though it doesn't really explain why it doesn't happen on kickdown.

Have you tweaked the wastegate actuator arm at all? I had a similar(ish) issue when I overtightened it.

[merc85]

No was doing it with the old gauge fitted, cant understand why after the boost cut it will hold a higher boost pressure when i use kick down with no cut coming in?

Yes i have adjusted the arm half a turn but this improved things.

[AndysR]

When you use the kickdown does the box drop a gear or does it remain in the same gear?

[merc85]

Hi Andy, She drops down a gear

[AndysR]

Maybe it's the higher engine rev's that help it to deal with the boost pressures stopping it from boost cutting. Personally I would invest in a remap to deal with the boost rather than trying to fool the system into thinking it's not boosting as high as it is, not to mention that the remap will recognise and be mapped to run the increased boost pressures maintaining AFR's more efficiently and consistantly.

[merc85]

Hi, Andy thanks for the imput, I will be getting a re-map, very soon it's just trying to find the right map at the right price.

I want to be running a mbc so i can control the boost but i do not want all the power low down, i really could do with it midrange to top end.

All to often i get to much wheel spin and dont go anywhere then have to wait for the power to come back through. not interested in sprints as this is no good for engine or gearbox's.

But it's all down to a price, just trying to find a fine balance.

Cheer's be good to meet up soon.

[AndysR]

Hi, Andy thanks for the imput, I will be getting a re-map, very soon it's just trying to find the right map at the right price.

I want to be running a mbc so i can control the boost but i do not want all the power low down, i really could do with it midrange to top end.

All to often i get to much wheel spin and dont go anywhere then have to wait for the power to come back through. not interested in sprints as this is no good for engine or gearbox's.

But it's all down to a price, just trying to find a fine balance.

Cheer's be good to meet up soon.

It might be worth you considering a turbo tuner ecu and getting it mapped to your requirements, im going to fit the intercooler in mine this weekend and might take it for a test drive. If I do I will see if I can pop over your way and show you how the turbo tuner in mine is.

[merc85]

Hi Andy,I have pm'd you

[p fandango]

the MAF limit (boost cut) is worked out by the % of air passing thru the MAF & the engines rpm, so the higher the revs the more boost the ECU will be happy with. Thats why when it kicks down it lets you run a higher constant boost

[AndysR]

PM replied.