850 tdi POWER!!!!!!

[thetroublemaker]

thats a weird looking MBC.

This is the type you should buy


- note the big 8mm hex and 17mm nut for the adjustment. Your car is msa15.7 so i cannot comment specifically on the wiring - the MSA 15.8 one i have looks different.

[fuller0554]

Mite be abit af a daft question but is there a certain size of mbc the should be used. Also, reading some of the earlier comments theres mention of a 3bar map/maf, is this referance to an upgrade airflow meter or standard boost control etc.

[martin_r_smith]

It's the manifold absolute pressure sensor. Basically its the sensor that monitors the boost and tells the ecu whats going on. Our cars have a 2.5 bar sensor, meaning it will monitor upto 1.5 bar of boost over atmospheric pressure. So if you try and whack over 1.5 bar boost through it will simple say no and put you into gimp mode.

You can replace the 2.5 bar with a 3 bar so you can run more boost, but there is no need to run over 1.5 bar with a standard injector setup.

[martin_r_smith]

As for mbc the one pictured above is the right kind.

[thetroublemaker]

As martin says, a 3 bar map sensor will not be needed, and to be honest you are getting towards the area of caution as these are high compression engines. Certainly 1.5 bar (21.75psi) is plenty for these engines. yes you can run higher, tdiclub has people running up to 28psi daily but you exponentially increase risk the higher you go. and boost means naff all on a diesel anyway to a certain extent.....

[fuller0554]

Ah i see that ok then. As for a mbc, when you say this type is needed do you mean visually this type is needed or are there different ones, ie ones that allow different volumes of vacuum pressure etc or are they all general the same but with different orientations of nozzles (in/out) etc

[martin_r_smith]

Originally Posted by fuller0554

Ah i see that ok then. As for a mbc, when you say this type is needed do you mean visually this type is needed or are there different ones, ie ones that allow different volumes of vacuum pressure etc or are they all general the same but with different orientations of nozzles (in/out) etc

I would get one that looks the same as the pictured one. They are so simple in there design and work perfectly, plus there only 10-15 quid on fleabay. There isn't different ones for different volumes no, as long as it's a ball and spring type it will be fine.

[fuller0554]

Ok thanks again mate.
Hey brickman have you managed to get yours running right now

[brickman]

Nope, returned to stock, and yes it achieves the boost it used to, but still with slower than standard spool up time, something somewhere is amiss but i've yet to find it.

As for the MBC, I don't think its the problem, but I've ordered a little brass item instead just to eliminate it from the issue.

I'm wondering if my cat is blocked or beginning to collapse. Prob a good time to drop it and hammer it out anyway.

[klunk]

Brickman, Decatted mine, 30 yrs in the motor trade and it is by far the filthiest job i have ever done, I looked like a coal miner! Got a full carrier bag of broken cat and soot out of it, Car goes so much better, Spools up earlier and no clouds of black smoke on WOT after its been idling anymore + an improvement on MPG, If the EGR's been blanked a decat should be done at the same time to get the EGT's down a bit.