Hitting boost cut in my BF5 TD05

[Blake7]

Hi guys

I just got my car back from the mechanics who installed a td05 and a v2 sti ecu. When I'm boosting it hits boost cut at the end of the revs the power dies and puts out a big puff of black smoke. How can I stop this from occuring? Would a boost tap fix it? Chip the ecu? Spoke to a Subaru guy and he said there's nothing I can do except put the factory turbo back on? Is this really the case?

Thanks in advance

[Koom]

Is it hitting the boostcut or the rev limiter?

Boostcut is easy to fix, but a boost tap or EBC on it and wind the boost down below the boostcut threshold. You can also chip those ECU's to run 14 or so psi. Will be very much near the peak flow of your injectors though unless you get a chip that allows you to swap to the yellow 440cc injectors.

Rev limiter is just as easy, .............change up a gear.

[Guest boostin]

Does the power taper off or is it a violent cut?

[Koom]

So at what boost level and what rpm is this occuring out of interest?

[Koom]

Back when I did similar, with a chipped ECU, it would freeboost high enough for the needle to fall off the guage and then have a rod jump out of bed.

Could also pay to get the AFR checked as mine was super lean anywhere over 10psi. Also had GTB heads on it at the time to exacerbate the problems.

[G-unit]

ok 1st off u need a boost gauge to see what its running, then see if it holds a certain psi or just keeps going up then bang boost cut

[Koom]

The factory controller cannot cope with a TD05 wastegate. Needs another controller on it.

But definately needs a guage to tell what he's setting it too otherwise I give it a week to live.

[Guest]

 Koom said:

The factory controller cannot cope with a TD05 wastegate. Needs another controller on it.

But definately needs a guage to tell what he's setting it too otherwise I give it a week to live.

Ha Ha that explains my problem as well, Old rs motor is back in but still TDO5

[Guest boostin]

But isn't the RS and V2 boost controllers the same? And i thought the V2 sti was tuned for a bit more boost too. Or is that just the RA?

[Koom]

I dunno but with mine it couldn't control it.

Actually rangi'ed it up with two solenoids at one point and it worked and held 15psi as it had before but then that was too much for it with the biggerer turbo and it ran lean. So I freeboosted it as it was more fun.

[Blake7]

Just bought a GFB boost tap and trying to source a gauge. My brain still works in PSI none of this "Bar" carry on. Will lay off the boost until fitted so im hoping this sorts it out.

Also fitted a V2 STI RA gearshift and linkages. Loving that..

[666SubSpeed]

i think the factory boost cut is 14.7 psi. thats what I hit and it feels like you have thrown an anchor out the window so now i have to control boost by not using full throttle thats with a vf10 factory ecu/injectors/afm and allmost everything else. hehehe and shes still going strong.

[Koom]

I wouldn't go past the boost cut. Especially if still using the grey 380cc injectors. I wouldn't even go near 15psi with a TD05 and greys.

[BC5RA]

Boost gauge is mandatory.

Bare in mind a TD05 at a lower level of boost would produce the same power as a VF8 at a higher level.

12psi should be enough, 15psi is asking for it; 17psi is a pull away from terminal engine failure.

Your 380cc injectors will be good for up to 180kw@wheels.

[Blake7]

This restriction due to the injectors maxing out? So chip with yellows etc and we can run 17 psi happily? Walbro in order then?

[BC5RA]

 Blake7 said:

This restriction due to the injectors maxing out? So chip with yellows etc and we can run 17 psi happily? Walbro in order then?

If your the type of person who looks at their engine like a pair of shoes.

[Blake7]

No wouldn't say that. Reliability is number one.

[kamineko]

well, i hold 19 psi to 8500rpm with spikes to 23psi on my td05 on yellows. might keep a spare pair of shoes in the boot.

[BC5RA]

12-14psi should be okay.

I wouldn't run anything higher than 10psi until you install a Walbro.

Run 98 only.

[BC5RA]

 kamineko said:

well, i hold 19 psi to 8500rpm with spikes to 23psi on my td05 on yellows. might keep a spare pair of shoes in the boot.

Just hold your mouth the right way

[kamineko]

haha.. yeah its certainly not ideal. i need a tune with less boost and more timing. but just giving an example of a td05 being fairly boost-happy.

i used to hit the same boost-cut in my factory V2 STIRA all the time after installing a decatted Siamese downpipe. - the main reason i upgraded to V3 ecu etc, the v3 map sensor has a wider range - higher boost limit.

[BC5RA]

My setup sees over boost in 5th gear; off the dial

I should have thought ahead and had the waste gate ported.

[driftrex]

ok so from my experience with my own v2 wrx, which is very similar to a bf legacy.

running td05, greys, factory wrx ecu (boost cut is 14.7 i think) i ran 12psi no issues at all then moved up to just under 15psi on the same setup.

running td05, greys, upgraded to sti-ra ecu (boost cut moved up to 17-18psi), ran 15psi all day every day for quite a while, i was using an external wastegate with appropriate springs to control boost level.

even had some springs in there for a week or so that allowed it to run 18psi but it would just hit boost cut sometimes lol, was really quick and RWD at the time, was totally dangerous in the wet though at speed when hitting bumps in the road lol, so i dont recommend that. but hey the engine survived.

so all in all i have owned my car over 3 years (60,000kms) and it has run 15psi nearly the whole time on standard grey injectors and fuel pump, this engine is still in my car and is currently having lots of mods done to support more power/boost.

so i would say 15psi is safe but wouldnt go any further.

[DRFVDR]

I ran my '90 GT manual with approx 15 psi for about 9 years and 200,000 K's until engine finally did a BEB and that was with stock injectors and ECU (was something different about the ECU as it was quicker than it shoulda been ??)

was running a Pod and an exhaust

[driftrex]

 Blake7 said:

Is it worthwhile upgrading to a sti fuel pump? Can pick these up cheap. Any version better/easier to fit than another for a BF5? After putting in the td05, sti ra ecu and shifter kit shes a different animal. Pod, cai and box, intake pipe and gfb boost tap to go.

nope not a worthwhile upgrade, just go straight to a Walbro 500hp pump, can pick them up through our club sponsors for around $180 delivered.

and yea that sti-ra ecu is the best you will get without going to a aftermarket ecu, made a huge difference to my car when i ran one.