Boost pressure dropping and surging

[ls_stag]

Hey all,

I have an occasional situation when I drive very hard in my S2 NEO Manual 4WD Stag - boost pressure loading up, and all of a sudden dropping very low, then bouncing back up again. Drop and surge, it seems. Not consistent and doesn't happen that often, but has happened more than a handful of times. Seems to happen more when my boost controller is set to high boost.

Things I'm wondering about;

- fuel delivery issue
- spark issue (coilpacks?)
- boost limiter?

Some extra context; car has cat-back, BOV, EBC, boost gauge - none of which I installed. It's possible the EBC is set too high at 'high' mode. On one full boost run that didn't result in the boost dropping, I saw (to my shock), the aftermarket boost gauge go to 1 bar. Normally I see it going to about .7 bar. I don't have an OBDII reader or else I would check codes.

I'm thinking it's just set to boost too high, but interested if anyone has experience with something similar (I've read in another thread and it sounded like the factor boost limiter kicking in).

If it is boost limiting that's to blame, my guess is that I should be thinking about bigger turbo, fmic, injectors, fuel pump, nistune/safc. Would that be the right way of looking at it? Alternatively I'm wondering if I could add a SAFC as the next thing, to control how rich it's running due to the EBC.

Thanks

Edited July 19, 2016 by ls_stag

[YangLIU]

can you show the settings details for EBC? "high" settings is usless for us unless you provide each settings value.

try set "GAIN" to 0. high GAIN will cause boost spike.

Edited July 20, 2016 by YangLIU

[BoostdR]

sounds like boost or flow cut. A nistune will fix it.

[ls_stag]

17 hours ago, YangLIU said:

can you show the settings details for EBC? "high" settings is usless for us unless you provide each settings value.

try set "GAIN" to 0. high GAIN will cause boost spike.

Good point, tonight I will dig up a manual for the EBC online, and see what I can find. Low boost seems to be yielding a consistent .7 bar max boost. Car pushes far harder when set to high, but I will check settings tonight. EBC also has a 'manual' control with a little turnable knob. Will check that out as well (and obviously avoid overboosting). I'd like to be seeing 12 psi / 0.82 bar on the high setting. From what I've read, that sounds reasonable, running premium fuel, BOV and the cat-back.

[ls_stag]

15 hours ago, BoostdR said:

sounds like boost or flow cut. A nistune will fix it.

I figured that'd help a lot. Going to be tricky to find a tuner here in Vancouver, BC I think, and I'll have to wait a little while for the budget. In the meantime, I just want to have a consistent setup if possible!

[YangLIU]

5 hours ago, ls_stag said:

Good point, tonight I will dig up a manual for the EBC online, and see what I can find. Low boost seems to be yielding a consistent .7 bar max boost. Car pushes far harder when set to high, but I will check settings tonight. EBC also has a 'manual' control with a little turnable knob. Will check that out as well (and obviously avoid overboosting). I'd like to be seeing 12 psi / 0.82 bar on the high setting. From what I've read, that sounds reasonable, running premium fuel, BOV and the cat-back.

 

if there is no problem when using "LOW" profile. then set same value for "HIGH" profile. normally just SET ang GAIN could control the boost. then turn up SET value bit by bit until you see your target high boost. then turn up GAIN value bit by bit until you see boost spike, then turn down  GAIN value a bit. done.

normally i'd suggest use Blitz SBC/Greddy Profec EBC which could show real time boost graph that easy to setup by ourselves on the road.

Edited July 20, 2016 by YangLIU

[ls_stag]

 

19 hours ago, YangLIU said:

 

if there is no problem when using "LOW" profile. then set same value for "HIGH" profile. normally just SET ang GAIN could control the boost. then turn up SET value bit by bit until you see your target high boost. then turn up GAIN value bit by bit until you see boost spike, then turn down  GAIN value a bit. done.

normally i'd suggest use Blitz SBC/Greddy Profec EBC which could show real time boost graph that easy to setup by ourselves on the road.

Thanks for the tips! Having done some digging last night, I have figured out that I have an -ancient- HKS EVC 1/2. So it is very, very simple. After playing around and doing some runs in 3rd last night (driving), I have figured out that with the EVC turned off, I have constant 6.5psi, with it turned on to Low, I have constant 10psi, and I used the 'Manual' dial to achieve a constant 12 psi. I'm now very interested in getting my hands on a GFB G-Force II (http://www.gfb.com.au/products/boost-controllers/electronic-boost-controllers/g-force-ii-electronic-boost-controller-by-gfb), having seen a couple videos about tuning it. Looks like a great unit at a reasonable price.

Also, planning to get a Super-AFC II off ebay and do some fuel adjustments as I assume it's running rich, especially in the top end. Driving it with 3/4 throttle on high boost actually feels far more responsive, and changing through gears without redlining results in faster acceleration - feels like its running leaner and faster. Wondering if anyone has had success doing their own SAFC mapping without using a dyno? Saw a guy using a Zeitronix kit online, but that's another $300USD for the data logger/laptop software. It looked The Biz, but I'm wondering if it's possible to get a good map without such a heavy AFR logging system.

 

Cheers!

[YangLIU]

10 hours ago, ls_stag said:

 

Thanks for the tips! Having done some digging last night, I have figured out that I have an -ancient- HKS EVC 1/2. So it is very, very simple. After playing around and doing some runs in 3rd last night (driving), I have figured out that with the EVC turned off, I have constant 6.5psi, with it turned on to Low, I have constant 10psi, and I used the 'Manual' dial to achieve a constant 12 psi. I'm now very interested in getting my hands on a GFB G-Force II (http://www.gfb.com.au/products/boost-controllers/electronic-boost-controllers/g-force-ii-electronic-boost-controller-by-gfb), having seen a couple videos about tuning it. Looks like a great unit at a reasonable price.

Also, planning to get a Super-AFC II off ebay and do some fuel adjustments as I assume it's running rich, especially in the top end. Driving it with 3/4 throttle on high boost actually feels far more responsive, and changing through gears without redlining results in faster acceleration - feels like its running leaner and faster. Wondering if anyone has had success doing their own SAFC mapping without using a dyno? Saw a guy using a Zeitronix kit online, but that's another $300USD for the data logger/laptop software. It looked The Biz, but I'm wondering if it's possible to get a good map without such a heavy AFR logging system.

 

Cheers!

 

good to dig EVC problem.  i would still suggest the EVC which could show real boost graph that easy to tune the car by yourself

for safc, i would say you can tune by yourself on the road but at least you need AFR gauge with wideband O2 fitted

 

[ls_stag]

@YangLIUdidn't get around to saying thankyou for your post.

Going to rip out the old EVC and replace with electronic unit. Considering doing a Nistune upgrade on my ECU in the future, so going to leave the SAFC/wideband AFR gauge for now. Seems like I could get the Nistune + tune + wideband o2 sensor for only a few hundred more than the SAFC + AFR gauge setup.

[KiwiRS4T]

If you are going to spend megabucks on an electronic boost controller and a Nistune consider instead getting a Link Atom ECU

http://www.ebay.com/itm/Link-G4-Atom-ECU-Top-Quality-Entry-ECU-at-Budget-Price-4-8-12-cylinders-/122046134336?hash=item1c6a843840:g:bzUAAOSwqfNXiJHH&vxp=mtr

which together with a Mac valve will give you electronic boost control and a great ECU and you can get it tuned in Surrey (they are dealers - you might find a tuner closer):

Independent Speed Shop

604-533-1548

Surrey

Canada

British Columbia