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Technical Car releases boost pressure on gentle acceleration

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Technical Car releases boost pressure on gentle acceleration

Jacob

Jacob

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Hi,

bit of an odd one:

If I'm accelerating fairly gently say from 30-40 in 4th gear over say 5-6 seconds the boost builds then usually at just under 2000rpm the car lurches forward and you can hear the boost drop.

It seems like something is releasing the boost pressure but I'm not clued up on how diesels work in this area, it's the 1.9 engine and I think I'm right in saying that it has a recirculation valve as apposed to a BOV found in petrols?

Anyone have any idea as to what may be causing this or how to sort it?

Car is 56 plate 1.9 GPS with 85000 on the clock.

Cheers
Jacob
 
Jacob said:
Hi,

bit of an odd one:

If I'm accelerating fairly gently say from 30-40 in 4th gear over say 5-6 seconds the boost builds then usually at just under 2000rpm the car lurches forward and you can hear the boost drop.

It seems like something is releasing the boost pressure but I'm not clued up on how diesels work in this area, it's the 1.9 engine and I think I'm right in saying that it has a recirculation valve as apposed to a BOV found in petrols?

Anyone have any idea as to what may be causing this or how to sort it?

Car is 56 plate 1.9 GPS with 85000 on the clock.

Cheers
Jacob
Click to expand...


1.9's does not have a recirc or BOV.
Check your boost hoses for any leaks, do you have a boost gauge? what rev's does the boost drop off at?
 
Ah ok, how do they control boost, is it all from the ecu?

About 1900/2000 rpm it tends to drop off. But if I keep accelerating it builds back up as normal past these revs.

I've replaced both of the turbo to intercooler hoses and checked the rest and can't find any other leaks but I can't be certain.

When accelerating hard it doesn't do it though so not sure if it's a leak or not?
 
Jacob said:
Ah ok, how do they control boost, is it all from the ecu?

About 1900/2000 rpm it tends to drop off. But if I keep accelerating it builds back up as normal past these revs.

I've replaced both of the turbo to intercooler hoses and checked the rest and can't find any other leaks but I can't be certain.

When accelerating hard it doesn't do it though so not sure if it's a leak or not?
Click to expand...

right okay. yeah all ECU controlled on them.


when was the last time you cleaned the EGR valve out? does it feel like a hiccup when you get to that rev range?
 
Jacob said:
I haven't done it myself yer, it is on the very long to do list though.

Yeah a slight hiccup/pause/lurch as acceleration abruptly ceases, like taking your foot off the throttle very sharply.
Click to expand...

move EGR to top of the list and see how it goes. probally clogged with soot. I used to clean mine every 6months when I was doing many miles but its the short journeys that clog them up!
 
Jacob said:
Cleaned out my egr as @Reuuk suggested and happy days!

The egr wasn't particularly dirty and the pin and valve still moved easily but I cleaned it anyway, along with the intake manifold and what a difference, car is much smoother to drive and the boost issue has gone :D
Click to expand...



Glad its sorted for you bud :) I knew cleaning the EGR would make a difference, It did on mine :)
 
I have this same problem.
Accelerate, not harshly, and it seems as if it skips slightly ? Sounds like a loss of pressure and then carries on fine.
I was told by a tuning company local to me that it could be to do with the dual mass flywheel. I'm not an engine guru but worth a look into maybe
 
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