Inconisant boost fiqures - MTE'd 850R

[Saaamon]

I've got an MTE stage 2 remap and it should be boosting about 18psi, but on my digtal boost gauge it shows its boosting all over the place. Sometimes it goes up to 16.5psi then othertimes it wont go above 13.5psi but either way you never no what it will boost in any given "burst" (30-100mph etc).
I've been told this is probably a weak actuator, does this sound right?

Saaamon

[tandino]

More than likely a faulty BCS....
If you had a weak actuator you wouldnt get upto 18psi period.

[My T5]

Would the under bonnet temp affect this at all? ie. hotter air,less dense ,causing less boost pressure?

[Saaamon]

More than likely a faulty BCS....
If you had a weak actuator you wouldnt get upto 18psi period.

This is what i thought at first but was dismissed quickly by a local rolling road operator that i use.

Saaamon

[MrMopp]

I would agree with tandino it sounds like your BCS is up the shoot :)

[tandino]

This is what i thought at first but was dismissed quickly by a local rolling road operator that i use.

Saaamon

If your actuator spring was weak the pressure in the turbine housing would open the wastegate 'flapper' well before 18psi even if your BCS valve was diverting all pressure from the actuator (leaving just actutor spring pressure to hold back the exhaust pressure in the turbine).
Trust me mate, ive been pissing about with turbo's for longer than i care to think about and 18psi doesnt equal a weak actuator spring:daisy:

[AndysR]

If you want I have a spare BCS which was removed from mine when I had boosting issues, which turned out to be a faulty actuator, that you can borrow ;)

[volvolised]

If your actuator spring was weak the pressure in the turbine housing would open the wastegate 'flapper' well before 18psi even if your BCS valve was diverting all pressure from the actuator (leaving just actutor spring pressure to hold back the exhaust pressure in the turbine).
Trust me mate, ive been pissing about with turbo's for longer than i care to think about and 18psi doesnt equal a weak actuator spring:daisy:

NOT for the sake of an arguement but haven't you just answered the post::: I've got an MTE stage 2 remap and it should be boosting about 18psi, but on my digtal boost gauge it shows its boosting all over the place. Sometimes it goes up to 16.5psi then othertimes it wont go above 13.5psi but either way you never no what it will boost in any given "burst" (30-100mph etc).
I've been told this is probably a weak actuator, does this sound right?
So it does sound like the actuator then ??

[Saaamon]

If you want I have a spare BCS which was removed from mine when I had boosting issues, which turned out to be a faulty actuator, that you can borrow ;)

That would be very good of you if you don't mind, as you know i'm getting very frustrated with my car not boosting properly atm. I'll try your BCS and if that doesn't work i'm going to see Russ with a blank cheque!! lol
I'll call you nearer the weekend to meet up if your free, thanks Andy.

Saaamon

[RT MECHANICS]

That would be very good of you if you don't mind, as you know i'm getting very frustrated with my car not boosting properly atm. I'll try your BCS and if that doesn't work i'm going to see Russ with a blank cheque!! lol
I'll call you nearer the weekend to meet up if your free, thanks Andy.

Saaamon

Hi Saaamon

How long has it had a tune was it ok to start with or just started this problem ??

Russ

[volvolised]

:stupid::stupid:b have you contacted the supplier since the problem started, what did they say, did they offer any advice....

[Saaamon]

Hi Saaamon

How long has it had a tune was it ok to start with or just started this problem ??

Russ

Hi russ, Its had the map on there for about 2months. I've only just had a digtal boost gauge fitted recently because i knew it wasn't making the right boost fiqures. It seemed to boost fine before i had it re-mapped, the needle on the dash used to go 3/4 into the white before so i assumed it was fine. When your driving though you can't tell its boosting wrong, its only when you look at the display.

Saaamon

[tandino]

NOT for the sake of an arguement but haven't you just answered the post::: I've got an MTE stage 2 remap and it should be boosting about 18psi, but on my digtal boost gauge it shows its boosting all over the place. Sometimes it goes up to 16.5psi then othertimes it wont go above 13.5psi but either way you never no what it will boost in any given "burst" (30-100mph etc).
I've been told this is probably a weak actuator, does this sound right?
So it does sound like the actuator then ??

No, its not the actuator.
If the actuator spring was weak it wouldnt boost to 18psi one minute then 13 psi the next.
Spring rates dont suddenly change from one minute to the next.

[AndysR]

That would be very good of you if you don't mind, as you know i'm getting very frustrated with my car not boosting properly atm. I'll try your BCS and if that doesn't work i'm going to see Russ with a blank cheque!! lol
I'll call you nearer the weekend to meet up if your free, thanks Andy.

Saaamon

Of course no problem to meet up probably better on Sunday if your cool with that as I only have a window of about 2 hours on Saturday so not really long enough to get over to you and back again.

Keep your cool with her though I know it's frustrating not running the right boost pressures as I have been there myself. It's been sorted now thanks to Russ however I am living with a nightmare of a blanket misfire which is doing my box in far worse than the boosting issue ever did!! So it's back to Russ to get that issue sorted. I am sure these issues are sent to test us....

Car's don't you just love them! lol

Btw if you do take yours to Russ and it works out about the same time as mine is ready to collect I don't mind giving you a lift back :)

[Saaamon]

Of course no problem to meet up probably better on Sunday if your cool with that as I only have a window of about 2 hours on Saturday so not really long enough to get over to you and back again.

Keep your cool with her though I know it's frustrating not running the right boost pressures as I have been there myself. It's been sorted now thanks to Russ however I am living with a nightmare of a blanket misfire which is doing my box in far worse than the boosting issue ever did!! So it's back to Russ to get that issue sorted. I am sure these issues are sent to test us....

Car's don't you just love them! lol

Btw if you do take yours to Russ and it works out about the same time as mine is ready to collect I don't mind giving you a lift back :)

Nice one cheers for that mate, well i'm aimming to take my car up to Russ if it needs to go that is, towards the end of feb. Hopefully i want to try and arrange it so it can be fixed in a day as need my car atm.
As for meeting up at the weekend i could always meet you closer to yours if you wanted, just to save you in petrol but we can discuss that nearer the time.

Cheers for the help,
Saaamon

[PNuT]

When your driving though you can't tell its boosting wrong, its only when you look at the display.

Saaamon

you should feel quite a difference between 18 & 13psi..... i would question the gauge as much as anything going on what you have said

[Saaamon]

you should feel quite a difference between 18 & 13psi..... i would question the gauge as much as anything going on what you have said

Its meant to be boosting 18 psi, however its only boosting between 13.5 and 16.5 psi.

[jez.w]

Outside air temperature makes a big difference. Over christmas when it was really cold -5 degrees etc my car was off the end of white gauge (I have a RICA 280). At the moment its at the end of white gauge. In the summer it will be a bit less. Cold air more dense, more air = more boost.
Also try another gauge as this could well be the problem, If your car is showing 13 psi, then to 16 psi you should feel the difference in boost. Are you sure that you should be getting 18 psi? That seems a bit high to me?

[Alan M]

At the end of last year I had a similar problem. I found out that the two BCS valves I had for the 850 were faulty. I replaced mine for a 2001 70 T5 BCS for £39 off Rufe and I now have a stable boost value every time my foot is planted. My boost would be one value at one point then another the next, much similar to yours. The later model BCS are much cheaper and I think work much better, but then I compare that evaluation to the faulty units I was using lol.

[BruceT]

At the end of last year I had a similar problem. I found out that the two BCS valves I had for the 850 were faulty. I replaced mine for a 2001 70 T5 BCS for £39 off Rufe and I now have a stable boost value every time my foot is planted. My boost would be one value at one point then another the next, much similar to yours. The later model BCS are much cheaper and I think work much better, but then I compare that evaluation to the faulty units I was using lol.


Whats the part number?

[Alan M]

PM Rufe and he can give you the option. The S60r unit is also the same price.

[Big Pete]

is it ok to use one off a newer model, S60r for example, is it a straight swop?

[Alan M]

Yes its a straight swap but you will need to mount it differently to the standard one.

[AndysR]

Nice one cheers for that mate, well i'm aimming to take my car up to Russ if it needs to go that is, towards the end of feb. Hopefully i want to try and arrange it so it can be fixed in a day as need my car atm.
As for meeting up at the weekend i could always meet you closer to yours if you wanted, just to save you in petrol but we can discuss that nearer the time.

Cheers for the help,
Saaamon

Driving isn't an issue chap as its something I enjoy :) Let me know what you want to do Thurs/Fri time if your still up for tinkering with it :)