help getting to the bottom of my vf35 boost problem....
28 December 2013, 12:24 AM
#1
help getting to the bottom of my vf35 boost problem....
right im really getting ****ed off with my vf35 hesitation and im determined to find out whats causing it....
my car is a wrx blob that was fitted with an sti8 bottom end and wrx heads,i had it fitted with a vf35 bought from matty on here and i had it mapped @ rcm on their dyno by duncan race dynamix.
the car made 354bhp @ 1.45 bar but sadly the car big-ended on the dyno so i never got to drive it.
i bought a sti8 long engine from matty (from the same car that the turbo came from) fitted it with new timing kit/oil pump/seals etc etc and i had duncan out to tweak the map to suit the new engine but ever since this new engine has been fitted the boost problem has been there.
i dont think it was there before as duncan would have noticed it during mapping,so between swapping engines it has happened.
it boosts fine in 1st and 2nd but 3rd/4th/5th @3800 revs + it sort of hesitates and it makes like a pft pft pft pft pft (sort of flutters)noise and basically the engine struggles to pull through it-if i feather the throttle ie back off slightly then re-apply it doesnt do it and pulls like a train to the redline.
it also doesnt do it if im slowly taking the car up to the 4k rev mark-its only when im driving it "enthusiastically"
ive had duncan look at it a few times and there is nothing in the map that suggests there is a problem,he even turned the boost down to 1.4 bar but it still happens.
the full spec of the car is this (nothing has changed from the original mapping session apart from the engine itself)
rcm headers/venturi up-pipe/3" bell-mouth de-cat japspeed downpipe all heat wrapped
3" de-resonated de cat center section from scoobyworld
afterburner raptor backbox
rcm induction kit with scoobyworx silicone airbox hose/intake pipe
rcm 340 fuel pump
sti top mount with oem dump valve and sti undertray
650cc flow matched injectors from cannon fodders old car fitted with new seals
sti inlet manifold-tgv delete
ngkpfr7b plugs
vf35 turbo-non ported came from a 75k ppp blob sti
sti 8 long engine from same car as turbo-avcs is NOT running as i havent wired it up
standard fuel pressure reg altho i have a 3 port fuelab to be fitted next week to cure a fueling problem as the car is struggling to start from cold and when warm it gives off black smoke when started
the engine is a gem,it uses no oil/water at all.its been in 6 months now and i havent had to top it up once
i have been given various answers as to whats causing it.......
cavitation
surge
its because im not running the avcs
silicone intake pipe may be causing irregular airflow at high rpm
maybe fuel pressue related as they can cause hesitation when faulty
does or has anybody had similar problems?
im about to start getting parts for a 2.1 stroker but i will be devastated if when i come to have the new engine mapped that the problem is still there should it not be turbo related
any help guys as this is really causing me not to enjoy the car.
surely if it was turbo related it would have done it on the original engine and during the mapping session?
heres the engine that big-ended
heres the engine i have fitted now
heres the power graph etc,as you can see the turbo pulled strong and made awesome power for a vf35
my car is a wrx blob that was fitted with an sti8 bottom end and wrx heads,i had it fitted with a vf35 bought from matty on here and i had it mapped @ rcm on their dyno by duncan race dynamix.
the car made 354bhp @ 1.45 bar but sadly the car big-ended on the dyno so i never got to drive it.
i bought a sti8 long engine from matty (from the same car that the turbo came from) fitted it with new timing kit/oil pump/seals etc etc and i had duncan out to tweak the map to suit the new engine but ever since this new engine has been fitted the boost problem has been there.
i dont think it was there before as duncan would have noticed it during mapping,so between swapping engines it has happened.
it boosts fine in 1st and 2nd but 3rd/4th/5th @3800 revs + it sort of hesitates and it makes like a pft pft pft pft pft (sort of flutters)noise and basically the engine struggles to pull through it-if i feather the throttle ie back off slightly then re-apply it doesnt do it and pulls like a train to the redline.
it also doesnt do it if im slowly taking the car up to the 4k rev mark-its only when im driving it "enthusiastically"
ive had duncan look at it a few times and there is nothing in the map that suggests there is a problem,he even turned the boost down to 1.4 bar but it still happens.
the full spec of the car is this (nothing has changed from the original mapping session apart from the engine itself)
rcm headers/venturi up-pipe/3" bell-mouth de-cat japspeed downpipe all heat wrapped
3" de-resonated de cat center section from scoobyworld
afterburner raptor backbox
rcm induction kit with scoobyworx silicone airbox hose/intake pipe
rcm 340 fuel pump
sti top mount with oem dump valve and sti undertray
650cc flow matched injectors from cannon fodders old car fitted with new seals
sti inlet manifold-tgv delete
ngkpfr7b plugs
vf35 turbo-non ported came from a 75k ppp blob sti
sti 8 long engine from same car as turbo-avcs is NOT running as i havent wired it up
standard fuel pressure reg altho i have a 3 port fuelab to be fitted next week to cure a fueling problem as the car is struggling to start from cold and when warm it gives off black smoke when started
the engine is a gem,it uses no oil/water at all.its been in 6 months now and i havent had to top it up once
i have been given various answers as to whats causing it.......
cavitation
surge
its because im not running the avcs
silicone intake pipe may be causing irregular airflow at high rpm
maybe fuel pressue related as they can cause hesitation when faulty
does or has anybody had similar problems?
im about to start getting parts for a 2.1 stroker but i will be devastated if when i come to have the new engine mapped that the problem is still there should it not be turbo related
any help guys as this is really causing me not to enjoy the car.
surely if it was turbo related it would have done it on the original engine and during the mapping session?
heres the engine that big-ended
heres the engine i have fitted now
heres the power graph etc,as you can see the turbo pulled strong and made awesome power for a vf35
Last edited by the shreksta; 28 December 2013 at 12:29 AM.
28 December 2013, 12:41 AM
#5
quite honestly mate i dont know why you persist with it, its a bag of problems. even if you do get it all finished with a 6 speed and stroker in it the cost will be stupid for what you have got.
id cut your losses as you cant enjoy owning a car that has so many problems.
id cut your losses as you cant enjoy owning a car that has so many problems.
28 December 2013, 07:14 AM
#6
quite honestly mate i dont know why you persist with it, its a bag of problems. even if you do get it all finished with a 6 speed and stroker in it the cost will be stupid for what you have got.
id cut your losses as you cant enjoy owning a car that has so many problems.
id cut your losses as you cant enjoy owning a car that has so many problems.
everything else is fine on the car gearbox/clutch/steering/brakes/suspension
its just 2 niggles that im determined to get to the bottom of
28 December 2013, 07:26 AM
#7
Hi Mark
I would speak with Duncan or mapper of yours choice and I'm sure he will get to bottom of it
Its does sound of it like momentary(split second) fuel/boost cut to me,have something similar when we run on WRX engine(on non stroker) LPG
Jura
I would speak with Duncan or mapper of yours choice and I'm sure he will get to bottom of it
Its does sound of it like momentary(split second) fuel/boost cut to me,have something similar when we run on WRX engine(on non stroker) LPG
Jura
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28 December 2013, 07:58 AM
#9
I cannot say for sure its mapping or ECU related,but can be too surge(boost creep) on the VF35,they're known for this and usually how you can solve this,is porting the wastegate,I think Big D done on his turbo this mode and his turbo made nice numbers
Jura
Jura
28 December 2013, 10:52 AM
#19
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Mine does a similar thing in terms of noise if I'm in 6th at low revs and put my foot down it sort of flutters still seems to pull ok though!
After I heard it I stopped doing it until I got my gauges fitted! Turns out the car peaks at 1.5 however when in 6th at low revs with foot down boost rises to 1.7
After I heard it I stopped doing it until I got my gauges fitted! Turns out the car peaks at 1.5 however when in 6th at low revs with foot down boost rises to 1.7
28 December 2013, 12:37 PM
#24
sorry to jump in but did you find out the pill hole size for a vf35 shreksta? thought id ask seeing as simon and duncan were on the thread. my sti had the pill missing so used a 1mm welding tip in place of a pill and its boosting to 1bar now and pulling like a train. just wondered if 1mm was the correct size for an sti? its a 2002 bugeye sti with vf35 btw.
28 December 2013, 01:38 PM
#26
cheers simon, so would it be worthwhile getting another one at 0.8 and installing it? maybe see a bit more boost? car has paperwork for an ecutek remap to 300bhp so i,d have thought it would run a bit more boost? my old wagon ran 1.3 bar at 315bhp.
28 December 2013, 03:33 PM
#29
28 December 2013, 06:21 PM
#30
sorted cheers guys,swapped the silicone intake pipe for the oem one today and its so much better
there is still a very faint trace of surge in 3rd and 4th @4k rpm but its hardly anything and the car pulls straight through it where as before it would just hold back,im guessing some porting on the turbo will help that last little bit
feels so much better now that i can keep my foot planted in 3rd/4th without having to back off,i guess the vf35 doesnt like a silicone intake
there is still a very faint trace of surge in 3rd and 4th @4k rpm but its hardly anything and the car pulls straight through it where as before it would just hold back,im guessing some porting on the turbo will help that last little bit
feels so much better now that i can keep my foot planted in 3rd/4th without having to back off,i guess the vf35 doesnt like a silicone intake