Can FAULTY n75 cause this

[bigjode]

I've tried that loads of times m8. I think limp mode is only 5psi max isn't it? I'm getting much more than that, just less than i'm used to.

Read the faults this morning - had 17608 - Boost Pressure Control Valve (N249): Mechanical Malfunction
P1200 - 35-10 - - - Intermittent

and the usual 17704 error in mapped cooling system. Although this one is no longer stated as being intermittent - so I guess its permanent and therefore more serious? For clarity, the car doesn't overheat, but sometimes it doesn't budge above 60 even after an hour or so with some spirited blasts involved.

block 118 (boost duty) never goes above 95% so I guess that its definately not a boost leak. (actual always meets requested too)

 

[bigjode]

well if its on a car thats running well its less likely to be a poorly one. when its new how would you know...

True

 

[bigjode]

Oh, I have bypassed the N249 about 6 months ago, so i'm a bit baffled about that fault

 

[andycupra]

if you bypassed the N249, i presume you bypassed it using pipework but left the electronic connections in place?

if so, the fault code may just be that the expected figures are not being seen.
or if you dissconnected it then the fault code will be due to that.

 

[bigjode]

Yes, bypassed pipework, connector still in place. But others have run with the bypass and no fault codes. at all? I may have a good look at it later.

 

[Kris]

For clarity, the car doesn't overheat, but sometimes it doesn't budge above 60 even after an hour or so with some spirited blasts involved.

Temp should be 90 at all times... I think?

 

[bigjode]

I know, thats the problem, it was underheating wasn't it? Thermostat maybe?

 

[bigjode]

gosh, I think I just need a new new engine.

 

[bigjode]

My plans for today are:

un-bypass N249, change vac hoses and disconnect boost guage (to eliminate an extra few meters of vac hose and see if i have a dodgy guage)

change temp sensor for a new one from a dealer (as opposed th eGSF ones i've had in the past)

if no joy, try new N75

then try new MAF

also get exhaust checked for leaks etc,

 

[Feel]

I had that N249 fault code on mine when the "y" pipe leading of f it was spilt I know yours is bypassed, but it might give you a clue. The car boosted fine though.

The temperature gauge could well be a faultly sender - I was told it was a fairly common VAG problem. Mine started to read only 70'C then the gauge packed up altogether, then it would occasionally work...

Don't know why your requested boost is so low though - I don't think that's an N75 problem (I think it would still request more boost than that, but just not deliver). I'm wondering if it's pulling back the requested boost because of another issue - I would run it past a Revo dealer if I were you and ask them...

 

[bigjode]

Right, I have discovered that this pipe has melted and there's a tiny hole in that i've made bigger by fiddling with it.

Question is, what is this pipe? On the leon, it doesn't have that metal pipe above it and its actually a "Y" pipe - One end goes to the back of the engine near the TIP (or maybe into the TIP), one end is connected as shown in the pic going directly into the engine, one end goes somewhere else that i can't trace it to.

 

[m0rk]

crank case breather

happened on someone elses recently too - wrap it in some tank tape for xmas

 

[bigjode]

Could this cause the problems i've been having - low/fluctuating boost?

 

[m0rk]

possibley - but I'd suggest the other hoses might be split too - hence dodgey boost control

http://www.seatcupra.net/forums/showthread.php?t=103052&highlight=crank+case+breather

 

[bigjode]

Right, replaced that hose today - no different.

When driving, i've noticed the DV sounds different when it dumps now. It makes more of a "tsh..tsh..tsh..tsh..tsh" noise, rather than a smooth "tttsssssshhhhhhhhhh" noise. (PS it was doing this before i replaced that hose aswel)

Any suggestions? Oh, also changed temp sensor for OEM VAG part (as opposed to GSF one I had)

 

[Feel]

Again, mine was making that noise (tcho-tcho-tcho) when the "Y" pipe off the N249 was split - from memory this is the one that goes to the top of the DV, have you chekced that one for splits/holes?

Maybe it's the same sympotom with a different cause but it would make sense that if the vacuum that opens the DV is building/falling/building/falling then you'd perhaps get the same thing?

 

[bigjode]

Ive checked the N249 as best I can but because its under that plate where the dipstick is, I can't see very much. I'll try again now its bright out...

 

[Feel]

Ah, sorry - I was thinking you had an LCR, in theory it should be the same, but probably a different hose layout...

 

[bigjode]

OK, cleaned up the N249, totally removed unused hoses to remove any possibilty of leaks in unwanted pipage

It now feels much better to drive! But boost is the same figure max 18psi. I repeat though it pulled very well through the gears.

Also, that weird "tsh tsh tsh tsh" dump noise has gone, now its just the usual tshhhh!

I changed the N75 for another and it still drove just as well but still didn't exceed 18psi boost.

I think I can rule out MAF becuase MAF flow looks healthy and it drives well.

I can hear what sounds like a small blow in the exhaust - can this cause a boost leak if its pre cat?

Am i just being paranoid? I'm nclined to give up ripping the car to bits just because the numbers seem off, but I can recall a time I could peak boost to 22psi

 

[andycupra]

18 sounds ok to me for a K03 / K03s. others are often a bit hight but not for long.