Mr Badger

Boost readings at idle -210mmHg and reasonably static +-1mmHg. I'm led to believe that this should be fluctuating around about the -400 or -500 mark! The hoses have all been checked over as best I can visually and I took the hoses off and finger over one end blew down them as hard as I could.

I was told when mapping the car that this was likely to be an electronic sensor fault as the reading is never usually that static. I got a new boost sensor and it still hasn't fixed it. It's very frustrating as I can't run my top map of 1.2bar because apparently it is clipping at the higher end - probably due to the same problem. I'm currently running 1.15bar map.

The car is MY98 Classic.









All hoses above checked.



I took off all the pipes around the boost sensor and checked they were ok visually, for blockages and leaks. I got a bit mixed up with a directional valve going to some sort of filter when doing this (please see other post).

When I take the blue indicated pipe off the directional valve, I get a very good vacuum and the boost reading goes all over the place. I can't remember if I get a -500 reading if I put my finger over the vacuum or if I leave it open - one or the other I think? Could this be a clue?

Help! Any clues anyone?

Mr Badger

bumpa bump bump

Jolly Green Monster

iTrader: (4)

is the connection to the dump valve good?

Mr Badger

Is this brass thing near the turbo the dump valve?



I've had a new turbo and dump valve fitted recently. I can't find and leaks around this area in the image above. Could it be a faulty dump valve?

I did notice that if I pulled off the hose going to the directional valve near the fuel vapour cannister - I got a strong vacuum and if I put my finger over the hose I got about -485. Is this a clue?

Excuse the crude diagram:-



Could it be the directional valve is faulty/leaking? Why does the vacuum go to the directional valve?

The rookie

iTrader: (1)

Well the manifold vacuum at idle has NOTHING to do with the turbo at all, and your pressure at -210 is HIGHER than the -400 to -500 your expecting (a depression below atmospheric) you should certainly be at about -500, why you arn't I don't know, it should require a massive amount of ignition retard to hold the engine speed down to idle speed with that little vacuum, so either the sensor is wrong (or you have a leak into the vac pipe to it) or you have a massive drag on the engine, you did of course do this fully warm coolant AND OIL?

From your diagrma it suggest that the charcoal canister one way valve is leaking and needs replacing. Its meant to move, not leak!

Simon

AndrewC

Connect a new piece of vacuum hose directly from the MAP sensor to a nipple on the inlet manifold - this will tell you if it's a leak in the pipework or a faulty sensor.

Judging by the airflow reading on your first picture this is a UK car?

Andrew...

Mr Badger

Errr. No the engine wasn't warm when these photos were taken but it has been a number of times and there are no differences. I have already swapped out the boost sensor and it made no difference.

I get a strong vacuum if I remove the hose at the directional valve before the charcoal cannister & put my finger over the hose I got about -485mmHg

Mr Badger

Yes, MY98 car. Is the MAP sensor the same as the boost sensor? The bit at the top in the photo below?



I get a strong vacuum if I remove the hose at the directional valve before the charcoal cannister & put my finger over the hose I got about -485mmHg. Isn't this an indication that the leak is nearer the directional valve/charcoal cannister?