Boost issue when pulling away!

[Westy]

I've had this issue ever since fitting a big FMIC and I just put it down to the boost system pressurising. Basically the issue occurs when first turning on the car and sometimes when sat at a junction or traffic lights.

As I go to pull away I can hear the turbo spinning via the Jetex cone then it will dump/divert by itself while my foot is still on the accelerator! I can only imagine that this is where the boost pipes and cooler are filling up but i've noticed it's started to get worse recently, doing it at most junctions if I have to stop for 30 seconds or more.

Anyone else experienced this?

 

[superkarl]

Whats your boost gauge saying / doing at this point?

 

[Rosso TT]

Did you try to disconnect the ECU fuse for 10 mins?
I had an under boost problem and this trick sorted it.

 

[Westy]

Whats your boost gauge saying / doing at this point?

It kind of happens to quick to notice anything. I'll see if I can get a vid of it.

Did you try to disconnect the ECU fuse for 10 mins?
I had an under boost problem and this trick sorted it.

I'll give this a go but is it the same as leaving the battery disconnected for a while as I've done that quite a lot recently.

 

[superkarl]

It may just be a characteristic of a big fmic. They tend to give boost spikes as they rush to meet pressures and fill the boost system, so maybe on part throttle and pulling away its not getting the pressures it wants. Sort of all or nothing if you get me.

Or maybe its down to your DV and spring?

 

[Westy]

It may just be a characteristic of a big fmic. They tend to give boost spikes as they rush to meet pressures and fill the boost system, so maybe on part throttle and pulling away its not getting the pressures it wants. Sort of all or nothing if you get me.

Or maybe its down to your DV and spring?

I've always put it down to the FMIC needing to fill with more air but it used to only do it first thing in the morning or when I turned on the car to go home. It now does it a lot more often.

DV and spring was serviced last year so should be ok.

The car performs fine under load but I thought I'd ask the question anyway.

 

[badger5]

n249 bypassed on yours yea? I dont remember

only thing which will lift DV is vacuum or boost pushing past it.

 

[Westy]

n249 bypassed on yours yea? I dont remember

only thing which will lift DV is vacuum or boost pushing past it.

Yeah N249 bypass.

What would cause the DV to open while I'm on the accelerator at low speed/load??

 

[<tuffty/>]

Yeah N249 bypass.

What would cause the DV to open while I'm on the accelerator at low speed/load??

vacuum... not on boost at that point... especially part throttle..

<tuffty/>

 

[Westy]

vacuum... not on boost at that point... especially part throttle..

<tuffty/>

So could a sticking DV piston be the cause?

 

[sideways steve]

It almost sounds like it is sticking however its possible its a weak spring in the DV.

Also what way round is your DV fitted ? is it a 007 ?

The correct way for a recirculating DV to be fitted is with the bottom connection (opposite vac pipe) to your pressure side and the side port to your inlet tract.... I know there will be people who disagree with this but I can assure you that is the correct way round.

Forge themselve also confirm thats the correct orientation however they do say they recommend fitting it the same way round as the original as it gives quieter operation. Personally I can see the argument for fitting it either way but if your having issues and its fitted the way I described above, try switching it round.

Another trick is to pop off the vac pipe to it and block it off whilst you try it again. This effectively disables the DV and stops it dumping however depending on which way you have it fitted you may get boost trying to force it open when the vac pipe is not connected as its purpose is to balance the pressure and prevent it from leaking under boost whilst helping it to open quickly on lift off to dump the boost.

 

[Westy]

It almost sounds like it is sticking however its possible its a weak spring in the DV.

It's a yellow spring but I suppose it could be tired. Think I've got a spare one somewhere, i'll have a look.

At least I have a few things to try now anyway.

 

[sideways steve]

Westy, see my edited post above too

 

[Westy]

Westy, see my edited post above too

Cheers Steve.

At present I have the bottom part of the DV into the TIP and the side part goes off to the charge pipe. I have tried it the other way round in the past and it just sounded like a whistle. I'll give it a go though.

 

[sideways steve]

I wouldnt bother switching it as the way you currently have it will be the better seal so if its leaking that way round there is deffo something not right with it !

 

[StaceyS3]

Could it be the throttle body or position sensor causing the inlet Mani to create vacuum opening your dv??

 

[Westy]

Could it be the throttle body or position sensor causing the inlet Mani to create vacuum opening your dv??

I dont get any other throttle related issues but I'll re-align it anyway, thanks for the suggestion mate.

 

[Westy]

I had my DV apart on Monday night and noticed that the lube that i'd put around the outside of the piston had dried in places (probably from the heat in the bay) and the piston didn't move as smoothly as it probably should have. I wiped off the crap stuff and smeared the little bit of good grease around the piston and so far I've only notices the issue once since.

Does anyone know If I can get away with using a different lube to the stuff forge send out with the service kit?

 

[Prawn]

I'd imagine you could use a good quality silicon grease mate, I wanted to clean mine out today and re grease it, but I only had normally CV grease, which will damage the seal.

 

[Sandip]

I used this in my milltek dv, seemed to work ok > MINTEX BRAKE LUBRICANTS CERATEC - Ceratec Advanced Brake Lubricant 75ml tube £2.29 Mitsubishi FTO Parts, Tuning, Spares & Accessories FTO Brakes - Other Brake Parts