MBC advice

[juggernaut]

I borrowed an MBC from a mates car to try on mine to see if it made any difference and was pleasantly surprised it did! Only problem was that it was overboosting and cutting the fuel, we tried to wind out the MBC but it ran out of adjustment.So before I buy one I need to find one that can be adjusted correctly for the Volvo.Has anyone on here used the MBC from Parts for Volvos online? Was thinking of getting one from them as they sell Volvo parts (obviously!!) so it might be more suitable.

[Tiff_T5]

Have you bypassed the boost control solenoid? If you leave this in line,the ECU will see the increase in boost and cut the ignition..

[juggernaut]

I did bypass the BCS but I'm trying to keep that "inline" as a safety feature if possible. I just want to set the MBC to the maximum setting before the BCS cuts in but as I said the MBC I tried ran out of "decrease boost" adjustment before this happened.

[t5tart]

Have you bypassed the boost control solenoid? If you leave this in line,the ECU will see the increase in boost and cut the ignition..


ok gimme a clue here
where is the bcs (thanks for answering what it is)

what does it look like any pics??
as my car has been played with in the past i want to try and find out as much as i can about whats been done

[Tiff_T5]

BCS is the "Boost control Solenoid" it lives,attatched to the side of the airbox,and has 3 pipes and an electrical connection to it.If it has been bypassed the pipes will hae been cut,but the electrical plug should still be in place.It basically tells the ECU the boost level.There is an article about MBC fitting in the Volvospeed pages.

[t5tart]

BCS is the "Boost control Solenoid" it lives,attatched to the side of the airbox,and has 3 pipes and an electrical connection to it.If it has been bypassed the pipes will hae been cut,but the electrical plug should still be in place.It basically tells the ECU the boost level.There is an article about MBC fitting in the Volvospeed pages.


right i have a mbc

no air box but the pipes goto the bcs

all the pipes are attached to the bcs but i believe from memory and without checking the mbc is on the center pipe ?

[Tiff_T5]

If the MBC is bypassed,it shouldn't be on any pipe to the BCS. It should be between the wastegate actuator and inlet side (the pipe has to be cut)

[t5tart]

If the MBC is bypassed,it shouldn't be on any pipe to the BCS. It should be between the wastegate actuator and inlet side (the pipe has to be cut)


now as a n00b
im totally confused
looks like a trip to bells to see madness to have it checked roflamao

[LeeT5]

I did bypass the BCS but I'm trying to keep that "inline" as a safety feature if possible. I just want to set the MBC to the maximum setting before the BCS cuts in but as I said the MBC I tried ran out of "decrease boost" adjustment before this happened.

:slap: Dude you need to do your homework first b4 you fit a MBC. You cannot fit a MBC and keep the BCS inline. The BCS does not 'cut in' as you put it. It is working all the time switching on and off very fast and it will actually allow the wastegate to open slightly (shuttling on/off) at only 1 or 2 psi.

You do not need to keep the BCS connected as a safety device because it will become redundant when the MBC is plumbed in.

Also you definately do not want to fit a MBC until you have fitted a seperate Boost guage (preferably in psi). The standard guage is very inaccurate and does not give a reading. Therefore you are not able to properly adjust the MBC.

TOP TIP: Fit a boost guage in a single pillar pod (£19.99 from Partsforvolvosonline) then check standard boost with BCS connected.
You should be boosting between 6-8 psi and (if auto) during gear change it will spike to 10psi for a nano second.

Then find thread on MBC fitting (is in the forum somewhere). You must remove ALL three vacuum hoses from BCS but leave it plugged in.
Ensure you do not use a 'BLEED TYPE' MBC. These are ££££e and weather conditions affect them. Ensure it is made of brass and is a spring and ballbearing type. Do NOT block up the smalll hole. Ensure you check all pipes fitted correctly (do this more than twice-otherwise be it on your head when the engine or turbo goes pop!!!)

Once happy with installation ensure that the adjuster thread is all the way out and locked off.

TAKE FOR A DRIVE, slowly increasing throttle. note the reading on boost guage.

:eye-poppi PLEASE NOTE THE FOLLOWING!!

Adustment must be minimal, ie do not wind in more than 1/4 turn. (lock off) go for a drive. Note boost again. As you boost towards 10psi decrease turns to 1/8 of a turn else you WILL hit overboost and fuel ecu will cut injection.

Personally i have found i cannot boost more than 11 psi. However i have mine set to 10.5 psi. This is plenty and believe me you wont really want more. Standard guage now goes off the scale :wow: and if the roads are greasy or wet you cannot floor it else its by by T5 hello hedge!! However in the dry the torque steer is incredible, starts to wheelspin past 30mph once traction stops control and will keep on spinning to 50-60 mph. :ukliam2: It is awesome.

With this one patience is a virtue and it could take you a few days to get it perfect. Also note that if you do hit overboost then you will need to reset ECU (because it remembers the overboost state and will cause you headaches, just when you dont want one). To do this just disconnect Battery earth for 15 minutes to enable ecu's to power down and reset.

Lastly....enjoy your new found power. :rally_dri :B_steerin :ukliam2: :band:

[LeeT5]

If you want to see pictures of my installation then keep checking NEW THREADS over the next few days. I have a smoked psi boost guage in a single right hand pillar pod. I have to say it almost looks OE cos the pod is black plastic. Take time when cutting, the end result is worth it. The gauge lights up with ignition so is on all the time when engine on.

I have had a few boy racers craning their neck to see it at traffic lights.... then i blow them away. LOL :B_steerin .

WATCH THIS SPACE. Anyone in the Maidstone area who wants to see install give me a PM and will arrange.

Lowering springs next from PFV online. :remybussi

[Tiff_T5]

Pretty much spot on,but you can keep the BCS. See Volvospeed,some pics here too. http://www.volvospeed.com/volvo_performance.php

Look under Modifications, Dawes Boost controller

[juggernaut]

Mmmm, seems opinions differ on whether you can keep the BCS or not. I am no expert on Volvos (hence this post!) but is it the BCS that gives you the "cut out" or is it the ECU? Also any advice on which MBC people are actually using on their T5's that work well?

[Tiff_T5]

Its the BCS which tells the ECU to "cut out"- its what gives the ECU info on the pressure being made bby the turbo.I bought an MBC off ebay for 20 quid,not much to them really,as long as they are quality.

[nobananas]

I found it usefull when I set mine up to set it to the boost I wanted off the car with an accurate boost gauge and a coolant system pressuriser pump (air pump). When I fitted it to the motor it was spot on !

[volvotuning]

Its the BCS which tells the ECU to "cut out"- its what gives the ECU info on the pressure being made bby the turbo.I bought an MBC off ebay for 20 quid,not much to them really,as long as they are quality.

No, the BCS is just a valve that is controlled by the ECU and it doesn't tell the ECU anything. The cutout is caused because the ECU is measuring a much higher air flow than it should be when you fit a bleed valve or MBC and cuts the engine off momentarily.

That is why the engine cut happens at different boost levels depending on ambient temp. When it's cold, the engine cut will happen at lower boost levels.

Adam.

[Tiff_T5]

Thanks Adam, I'm new to T5's..most of my experience with Turbo's have been with Audi's and Deltas. (old skool).Always keen to learn!

Could you explain a bit more, what actually measures the boost level in a standard T5 then,you say its airflow volume-so is it the AFM that decides when to send a signal to the ECU to cut out?

[LeeT5]

Its the BCS which tells the ECU to "cut out"- its what gives the ECU info on the pressure being made bby the turbo.I bought an MBC off ebay for 20 quid,not much to them really,as long as they are quality.

OK then (smartarse) :) so if the BCS 'tells' the Fuel ecu to 'cut out' then how the heck does it do that when on my car and nearly everyone elses (with MBCs fitted), it has NO vacuum lines attached therefore cannot possibly monitor a vac or pressure??????
eh eh ?????? :slap:

Come on man think about it!!!

I'm not a turbo expert and dont claim to be but with 16 years in the trade i know abit about what i'm talking about, and it dont takes the brains of an arch bishop to work that one out.

As far as i'm aware the 'fuel cut out' is more to do with air/fuel ratio and this is monitored by the Lambda sensors, temperature sensors and NOT the boost control solenoid. After all the word 'solenoid' means simply 'electrical switch or valve'.
And that is exactly what it is, a switch, NOT a sensor.

[Tiff_T5]

OK then (smartarse) so if the BCS 'tells' the Fuel ecu to 'cut out' then how the heck does it do that when on my car and nearly everyone elses (with MBCs fitted), it has NO vacuum lines attached therefore cannot possibly monitor a vac or pressure??????

I meant when an MBC is fitted with the BCS still connected,it even mentions this in the instructions that came with the MBC,that its a *bit* dangerous to disconnect the BCS,as then the MBC has full control of the boost pressure,and will keep boosting till it goes bang..I'm going on my own experience here.. why has mine never,ever cut out,even with the MBC screwed well in and 1.2 bar showing on the gauge,in December?? I crapped out,and dropped it back to 0.8

Wouldn't the ECU cut ignition,rather than fuel,a weak mixture,at high revs/boost would melt something..?? All it takes to cut ignition is a switch..??

As for smartarse,I also have 15 years in the trade,but learn something new every day.I knew nothing about T5's till about 2 months ago,I learn as I go!If I'm wrong,educate me! :drunk:

[LeeT5]

I meant when an MBC is fitted with the BCS still connected,it even mentions this in the instructions that came with the MBC,that its a *bit* dangerous to disconnect the BCS,as then the MBC has full control of the boost pressure,and will keep boosting till it goes bang..I'm going on my own experience here.. why has mine never,ever cut out,even with the MBC screwed well in and 1.2 bar showing on the gauge,in December?? I crapped out,and dropped it back to 0.8

Wouldn't the ECU cut ignition,rather than fuel,a weak mixture,at high revs/boost would melt something..?? All it takes to cut ignition is a switch..??

As for smartarse,I also have 15 years in the trade,but learn something new every day.I knew nothing about T5's till about 2 months ago,I learn as I go!If I'm wrong,educate me! :drunk:

Hey Tiff, dont take the last para to heart (was just having a dig!! :B_blite: )
I need to establish some facts b4 i can answer your Qs.
1) Do u have a seperate boost gauge?
2) After fitting MBC you should have found that the vac lines to the BCS were all redundant (all used by MBC).
3) Did you block the MAF connector?

If answers to all above were yes then you have a problem. Even boosting at 9psi you should hear the turbo really whistling loud, plenty of exhaust grunt too. If i can work out how to post photos on this site then i will post my set up, inc pillar pod and stealth boost guage.

[Tiff_T5]

No probs mate :),we all get "blank" moments sometimes.. (I hope??-or should I see a doctor??)).(note to myself,put brain in gear before using keyboard...)The answers are all yes to the above,car runs very well,no smoke,no power loss,no cut-out.no air leaks,no burst hoses.Does make a comedy hooting noise most of the time though.I've just replaced a cracked manifold today,but can't see this having any effect on anything-apart from on me-it was minus2!

Post your pics on www.photobucket.com,then copy and paste the IMG source on to the reply

http://i3.photobucket.com/albums/y73/tiffx19/oilseal.jpg

[LeeT5]

Post your pics on www.photobucket.com,then copy and paste the IMG source on to the reply

http://i3.photobucket.com/albums/y73/tiffx19/oilseal.jpg

WHAT? In English please!!!! yes i know :slap: :stupid:

[volvotuning]

Thanks Adam, I'm new to T5's..most of my experience with Turbo's have been with Audi's and Deltas. (old skool).Always keen to learn!

Could you explain a bit more, what actually measures the boost level in a standard T5 then,you say its airflow volume-so is it the AFM that decides when to send a signal to the ECU to cut out?

Yes, the MAF (Mass Air Flow) sensor readings determine the air flow. When this is too high compared to what the ECU is expecting, the ECU will give you the momentary "engine cut".

Adam.

[Tiff_T5]

Lee, go to the photobucket webpage, I think you have to start an account (its free) and the click on upload pics,-browse,then another window will appear,and you can then click on the pics you want to upload.Photobucket resizes them for you too.

[Tiff_T5]

Thanks again Adam,I've been doing a bit of reading and learning over the past couple of days...Audi's had K-Jet,and early Delta's had a sealed carb,so all this electronic stuff is newish to me! Remember our conversation in chat about old skool vs processors???


P.S I still prefer carbs.....

[nobananas]

It was far easier on older motors ,Renault 5's etc. These simply had a switch screwed into the induction pipe (boost side) which was set at a certain pressure slightly above the opening pressure of the wastegate and would cut the ignition if the boost rose too high. Of course most 'cappies' would disconnect them and then wind the boost up...POP !

[Tiff_T5]

Yup,them were the days! nothing,nothing,nothing then WHAM,wheelspin into the nearest ditch...where have all the Uno turbo's gone?? I've been looking for one for ages,to get the engine to put in my X1/9...there's none left!

[LeeT5]

where have all the Uno turbo's gone??

:rotfl: :rotfl: :rotfl:

...In a ditch!!