Strange Boost Drop...

[EZ Tutty]

Hey,

For a week or so my car has felt a little 'down on power', however today i watched the boost gauge quiet closely whilst driving (not looked at it in ages), and whilst giving it the beans the boost was peaking about 14-15psi, and dropping to about 10psi

However the car used to boost to 20-21psi then drop to about 12psi

spec in sig, N249 bypass done (however has been done ever since i had the car, recently new N75 valve aswell, i've checked all the vac hoses and connections etc, and everything looked fine.


Any suggestions?

 

[Miffer]

Hey EZ Tutty,

Did you get this problem sorted, because I have got the same symtoms at the minute and would be interested in what sorted yours.

Cheers,

Brian

 

[yellow_fever]

.

had the same problem mate when i done mine you seam to get the problem if your running the ko3 and not with the k03s reason being is that there are two pipes comeing from your turbo you have to block the 1 of that comes bk up to return where you had the n112 ect befor but leave the one that goes to the n75 as it is this fixed my problem as that pipe vents the bosst some how mate if i can be any more help plz ask

 

[Miffer]

had the same problem mate when i done mine you seam to get the problem if your running the ko3 and not with the k03s reason being is that there are two pipes comeing from your turbo you have to block the 1 of that comes bk up to return where you had the n112 ect befor but leave the one that goes to the n75 as it is this fixed my problem as that pipe vents the bosst some how mate if i can be any more help plz ask

Thanks for the reply yellow_fever, I am a little confused mate, I think you are referring to the N249 valve being done? I should have put down my spec down as I have not done the N249 mod, I am running a revo remap and a forge recerc DV and that's it. I was running a hurricane filter but took this of a month ago, I am running a standard filter in the standard air box......could this be the problem, do you need a free flowing filter or is the standard OK to run Revo.
At the minute the car runs fine apart from the lack of boost, I had a look this morning on the way to work and it seems to boost to 14-15psi then dropping to about 10psi then I tried to accelerate in 5th gear on the motorway and it boosts to 20psi but drops quickly down to 10psi again. 20-21psi is what I normally tend to boost to.
I have checked all the hoses and everything appears to be fine, there are no error codes on vagcom and no engine check light on the dash.
I have disconnected the MAF and it runs the same.
The dump valve doesn't seem as loud to me also, but this is probably the fact that there is less boost.

From what I have read in other threads I am tempted to change the N75 first.

Any advice would be good chaps as I have a new car coming in a few weeks and need this one sorted asap.

Cheers,

Brian

 

[Miffer]

Well I have ordered a N75 valve to try and fix the problem or at least to rule it out, what would be next thing to check/buy? The MAF? As I said I have disconnected the MAF and it runs the same (boosting low)

Cheers,

Brian

 

[Miffer]

I had a play with my Revo settings on the way home tonight and if I have it set to High Boost 7 (normally 20psi) then the boost goes to 15-16psi then drops sharply to 7psi after a few seconds, but if I have the Revo set to Hign boost 2 then the boost goes upto 15-16psi as before but this times holds this and tales off as the revs climb as you would expect.

I am not sure what this indicates

Also I have just vagcom'd it again and there were no fault codes still!

Cheers,

Brian

 

[Miffer]

Anybody

 

[Daz_gibbo]

Less is more with regards to Boost settngs when you have a fewer mods as you do. Otherwise with too high a setting (HB7 included) the ECU will pull back to copensate for excess heat etc. When you say your boost is dropping off what are you hitting at say 5k? As we all know you can't expect a ko3 to hold 20psi.

 

[Daz_gibbo]

just read you have VAGCOM. Why not do a boost and WG duty log? Blocks 115 and 118

 

[Miffer]

Less is more with regards to Boost settngs when you have a fewer mods as you do. Otherwise with too high a setting (HB7 included) the ECU will pull back to copensate for excess heat etc. When you say your boost is dropping off what are you hitting at say 5k? As we all know you can't expect a ko3 to hold 20psi.

Hi Daz,

When I have run HB7 at 5k I would guess it would be hitting say 14ish psi but yesterday and today as I mentioned it was only hitting 15psi and then dropping straight off to 7psi.

I been running HB7or7 for for years now, only with a hurricane filter on, I took this off a few weeks ago to put it back to a more standard spec for sale which could have affecting it as you say the excess heat etc and the poor standard filter but this was weeks ago and it has been running fine.

I might put the hurricane back on or just leave the Revo on HB2 as it runs great on this setting, I am just worried that there is a fault and the higher boost is exposing it and eventually it will fail completely, so I would like to get it sorted

It just the fact that it is a sharp drop off to 7psi and not a gradual drop in boost that you can get sometimes with heatsoak etc

 

[Miffer]

just read you have VAGCOM. Why not do a boost and WG duty log? Blocks 115 and 118

Just read this mate, I will have a look at this at the weekend, I have not really played with vagcom, just checking and deleting fault codes. Is it easy enough to do?

 

[Daz_gibbo]

Yes, go to Engine > measuring blocks and do a run from 2k through to 6k in 3rd or 4th if possible. Log each block seperatly for a good sample rate. Do you have the full version? If not you won't be able to log these blocks

 

[Miffer]

Yes, go to Engine > measuring blocks and do a run from 2k through to 6k in 3rd or 4th if possible. Log each block seperatly for a good sample rate. Do you have the full version? If not you won't be able to log these blocks

No not got the full version and to be honest I get my new car in 3 weeks so don't want to go and buy it, looks like I might have to just stick with the lower setting and hope nothing fails. I might try the hurricane at the weekend to see if putting this back on affects the boost in anyway, I think that's all I can do at the minute then.

Thanks for your help Daz