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Turbo, overboosting, help !!

5K views 7 replies 4 participants last post by  sussexa 
#1 ·
I recently replaced my intake manifold and EGR valve on my 1.9 jtdm and it ran like a dream for about 2 days... Then suddenly (not intermittently) the car was hesitant and very
Very hot although the temp gauge is normal...

Now even when the car is at tickover 750rpm I can hear the turbo spooling almost to its maximum despite being hesitant most of the time, when it's not I seem to have about a million horsepower !! Obviously the excess heat is coming from the turbo spooling constantly so I'm not using it much till the problem is resolved ... Here is what I've found at current ...

The turbo is less than 15k old so the likely hood of a failure is slim and there's only high boost noise, not bearing, and no play in the shaft.

Interesting, when I remove the skinny vacuum line from the front near the bonnet latch, it stops spooling and sounds normal but if I drive it like this the turbo noise dissapears but I obviously have no boost when I need it ! If I plug it back in it spools again right away !!! Faulty actuator ?? Are they vacuum controlled ?

The only other thing is when I initially start the car it doesn't start right, it misfires about 4 times before starting (almost once per cylinder) ... Now these two issues occured at the same time instantly, I've no management lights on or anything.

What could have failed instantly causing this issue .... It's as if extra vacuum is keeping the turbo actuator lodged open and spooling on the high vent vanes... But we know its not the actuator jammed because removing the vacuums line stops the problem ... I'm stumped !!!!!
 
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#2 ·
Ha ve you tried cleaning the boost valve on the slam panel? Normally has the opposite effect though.
I'd also investigate the water pump, they would have to take the timing belt off to do the manifold, and it goes round the pump.
 
#4 ·
Possibilty that the solenoid valve has stuck in fully open position, not sure but ive seen a thread on blocked vent filter also giving issues with valve.
A quick disconect of plug should prove if operational.
Ive also seen a stripdown of that solenoid somewhere on here but i think new are only £45 ish.
 
#5 ·
Update : it seems the vacuume solenoid is lodged open, perhaps the new manifold has increased the vacuume and finished it off, hence the vacuume won't close off and it keeps the turbo on full spool. I can only imagine this relates to the poor starting somehow.
 
#8 · (Edited)
As far as i know? Car gets vacuum from vac pump driven off camshaft front right of engine.
The vnt map i think calls for 75% (max)during starting anyway not sure how fast vac will build during cranking to pull actuator.
Id guess nothing to do with starting issue but keep in mind.
What was done with egr, much more likely to give starting issues if sticking open.
Id imagine warm engine would easily start without glow plugs if compresion in good order.
On a side thought
Any chance you got the wrong map sensor?did you compare bosch number.
If a 2.5bar sensor was fitted by mistake i would expect overboost .
And you can easily pull silicone pipe off actuator and confirm or deny it has anything to do with starting problems.
 
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