Fitting mbc

[Ardz83]

Hi guys
I'm fitting a mbc on my a4 and on the instructions it says to vent into engine bay. What does this mean exactly. I know alot of people are against these mbc's but i don't really want and full blow "why are you doing that for"

Any help with this would be appreciated.
Thanks in advance
Dan

 

[Oranoco]

Do you mean a MBC (Manual Boost Controller) as you seem to be describing a dump valve??

 

[Ardz83]

That's what I said mate. Mbc, I already got a spliter r on there.

 

[<tuffty/>]

You planning on fitting the MBC in parallel for controlling the spike or in place of the N75 for 'more boost'?

<tuffty/>

 

[Ardz83]

More boost!!!!! I'm only running 4 psi:-(

 

[<tuffty/>]

Using an MBC to produce more boost on an unmapped ECU will more than likely throw fault codes all over the place (depending on the ECU your car has) and potentially go into limp mode... if your ECU is not a wideband ECU then the fuelling won't be right and you stand a chance of it going lean and melting your engine...

There is a reason people give a

...full blow "why are you doing that for"

response... its normally due to the fact you can't just fit an MBC and expect to get more power... the ECU's std mapping is designed to work within certain parameters and thresholds and fitting MBC's in this fashion move the ECU out of its safe zone and fights back but going into limp or letting your engine eat itself..

A remap is the safest and realistically only way to get the power you seek...

DOn't get me wrong, I have have nothing against MBC's, I have used one myself but only to either prevent boost spikes or in the case of my car I have used it instead of the N75 and run lots of boost but then my engine is built for this, the mapping has been done for this and my ECU is wideband capable so adjusts fuelling accordingly...

I have also logged the car on the road and on the dyno to make sure that there are no issues with the boost levels I was running...

My advice is (as everyone else will no doubt tell you) is to get your car remapped...

<tuffty/>

 

[Ardz83]

I thought I would see if I fitted this mbc, I could run abit more than 4 psi. Trying to be cheap and not buy another n75 valve. I wasn't going to go mad and give it full boost. I totally understand what you are saying and I don't expect a mbc to be a remap but I was just being a tight git. Plus I would love to get my car remapped but you can't because mine needs chipping (1998 1.8t) 300 quid I don't have. Lol

 

[<tuffty/>]

Are you saying your N75 is not working which is one of the reasons for the change (other than more boost of course)?...

It is plausible to run an MBC to more or less the same boost levels you currently have but you would need to leave the N75 electrically connected to keep the ECU happy (providing its not faulting as open circuit or anything) and run the MBC to 4psi... you 'may' be able to tweak up the boost a bit as earlier ECU's can be more tolerant/too stupid to notice (take your pick lol) but you will need to block the TIP where the N75 connects or just join the 2 unused outlets with some silicon pipe to stop airleaks...

However, part throttle on MBC's is pretty awful... may not notice it so much on such low boost but its something to be aware of... as for the choice of MBC, I would not recommend anything other than the Forge UNOS as it just plain works... cheap bleed valves and the like are absolute crap affording no control and typically fall apart giving either no boost or all of it...

All you are really doing though is plastering over the cracks... the proper fix is a remap... get saving ;P

Revo are doing £100 quid (or so) off I think at the minute :thumbsup:

<tuffty/>

 

[Ardz83]

I'm think I will replace the n75 as the mbc was just one I found in the garage. Thanks for you input mate,you have educated me abit here

 

[<tuffty/>]

I'm think I will replace the n75 as the mbc was just one I found in the garage. Thanks for you input mate,you have educated me abit here

Welcome my friend

<tuffty/>

 

[aragorn]

Seriously, you need to get a vagcom lead and scan the car for faults.

 

[Oranoco]

More boost without more fuel = a bang and a big bill.

Contrary to popular missbelief there is nothing wrong with an MBC providing it's used correctly, set up and most importantly LEFT ALONE. My track car has run one for years with no problem and happily controls the 25psi of boost.

 

[aragorn]

Its not just the fuel though, its the ignition timing as well.

The map needs to be appropriate for the boost your trying to run.

The real point here, is that theres clearly a fault with the guys car, as hes only getting actuator pressure. It may be a faulty N75, or it could be any number of other faults that have forced the ECU to cut back the boost deliberately.

 

[Oranoco]

Oh absolutely, I was speaking in crude terms. Fuel and ignition maps need to work with the boost pressure