boost and boost gauge help!!

[e300]

Hi, i fitted myself one of those boost gauges yesterday just a cheap one for now but it will hopefully do the job, anyway, i tee'd it in to an airline that looks asthough it goes from the egr to some kind of sensor with 3 wires? does anyone know if this will give me a correct reading? if not, where should it tee in?
also, if it does give a correct reading, im getting about half a bar at full throttle, now i dont know anything about what the boost should be but that seems low?
Would a MAF sensor that isnt working right change boost pressure? Thanks

 

[nigel cross]

And what is this for?

 

[e300]

i just put it in to see what the boost pressure is and if its where its supposed to be, i could have been running with low boost or something, im just trying to make sure the cars all good while i have some time off work

 

[Olivier]

that'll be a good reading. The little sensor with the 3 wires is the turbo boost sensor for the ECU.

 

[e300]

I was hoping you might show up, ive read alot of your posts, thanks, would 0.5 bar be right then? and which of those 3 wires would i put the resistor that you talk about for increasing boost? and could you help with a broken MAF?

 

[Olivier]

not sure about 0.5 bars. Its 15 psi stock. I was going up to 18/19 after the wee mods.
not sure what the color of the wire was, sorry that was a while ago, its there somewhere with pictures I think.
for the MAF you could go to Peachparts,diesel discussions, maf elemination . Kartek there had a trick, it might work. I tried it but my E is poorly, hectic due to boost lost or fuel starvation. I need to tackle this before I can be sure Kartek mod is really good on mine. He'sthe man for the electronics
But if you do the MAF elemination you cannot do the boost increase as the ECU is only looking at the boost sensor( the 3 wired one) and if you change the value it is not good.

 

[Olivier]

Did you get sorted?

 

[e300]

Hi, sorry for not replying, my internets been off a while, i think my boost is low then, around 7psi! Ive just swapped the MAF internals with my brothers seat ibiza diesel and that hasn't improved boost maybe boost sensor?

 

[Olivier]

might be the wastegate that is open? Not closing properly? 7psi is indeed way too low If you suck into the pipe from the transducer that work the wastegate you should see it closing.
you might have a leak on the rubber pipes from the turbo to the intercooler or to the boost sensor? The pipes from the turbo to the intercooler are easy to spot if they leak as there will be a black goo ( engine oil) at the spot, the boost pipe is a wee more difficult as it might be a little hole that only shows under pressure. This might trigger the ECU to lower the boost?
Dirty/ sticky EGR valve ?

 

[Alex Crow]

Good advice above, as always.

The 4x most common causes of boost loss on this car are (in no particular order)...

Leaking intake system (hoses and/orintercooler mainly).
Blocked catalytic convertors.
Loss of vacuum supply (leaking EGR valve, rodent damage to vacuum pipes etc).
Sticking EGR valve.

Generally the turbos are bullet proof on these.

 

[Olivier]

Just a thought, how is your air filter?

 

[e300]

Ive just had a look around and the egr has black dirty oily stuff around the outside on the top half, could that be a leak? And a big enough one for my problem? Air filter was brand new last night the old one was very bad, going to try blowing the wastegate aswell now, thanks for the help, tips and advice so far

 

[e300]

Wastegate arm moves when i suck it too

 

[Dieselman]

Wastegate arm moves when i suck it too

Check it actually closes fully though.

 

[e300]

How do i know if its fully shut? I just removed and cleaned the intake manifold and egr, ive put it all together and got my normal half boost for about 2 miles then lost most of that, its only just moving the gauge off zero now any ideas on that now?

 

[Dieselman]

I suspect you now have and EGR fault causing limp home mode, which drops the turbo wastegate.

To check if the wastegate is closing fully, ensure the link rod goes tight just before the diaphragm reaches rest position.

 

[e300]

Can i see when the diaphram is at rest or just feel for it? I have my old boost back when the vacume pipe is disconnected from the egr valve

 

[e300]

Would less fuel cause less boost? Ive never changed the fuel filter since i had the car

 

[Dieselman]

Yes it will.

Check the MAF output first though as if the ECU sees less air being injected it will cut back fuelling accordingly, thus less boost.

 

[e300]

Ahh i see, ill go check the maf now, just changed oil, filter and fuel filter anyway, if maf is bad does anyone know where i can get one for less than £180? Best price i can find