lots of lag, low on power...can't figure this out

[tErbo b00st]

So a couple years ago I installed the blitz K26 Twin turbo kit. When I purchased this kit, the information out there was scarce, but everything I found said the kit should be good for upwards of 600 hp, with lag only slightly more then the stock twins. I'm only really shooting for about 450 whp, so I got a set of Sard 550cc injectors, an S-AFC (gen 1), and an AVC-R (gen 1) set at 18 psi. I figure 18 psi should yield me about 450 (maybe less because I'm using an S-AFC), and get me around 80% injector duty cycle or less.

Supporting mods
- Sard 550cc Injectors
- blitz supplied DP w/ 3" custom exhaust (same symptoms with open downpipe)
- Walbro 255
- large FMIC (forgot the brand, not ebay)
- Port and polished head to flow better then 2J head
- USDM 2J cams
- Twin K&N filters
- S-AFC (Gen 1 w/ 5 knobs)
- AVC-R (Gen 1)

Since then, I've battled the power and lag on this setup. Constantly checking for boost leaks, tweaking the EBC setup, replacing the intake setup, etc. I've gotten some minor gains, but I sit today with basically zero boost until 4,000 rpm, where it then starts to build boost and I have full boost by 5,000 rpm. The car is used for drifting, so while I can and have "made it work", this is a lot more lag then I had expected. On top of that, the car does not feel like it has 400+ whp, and several highway pulls vs friends cars ensures me that I am not at 400+. Finally, my AFC tuning doesn't really "make sense". At idle I had expected to pull 30% fuel, as the 550's are 30% larger then the stock injectors. If I pull 30% fuel the thing idles at like 18:1 AFR and wants to die. I've had it set at about -15% fuel at idle and 2400 rpm, and that brings my idle and cruising AFR to the 14-16 range. When I get on it, the thing is pig rich in the low 10:1 AFR, until boost hits where it stays around mid 11:1 AFR, but up top it leans out to mid-low 12:1 AFR...not good. The AVC-R also reads injector duty and it is saying that I'm at 100% duty cycle around 6,000 rpm. At the upper fuel adjustment points I have about -5% fuel pulled, it is just enough to not hit fuel cut at 18 psi.

I pulled codes yesterday and only got code 21, which is bad oxygen sensor. I will replace the sensor, but I don't believe that would give me the problems I'm having. I've also done a lot of reading about the fuel filter being an issue on some cars, but I can't make sense out of how that would cause extra lag. Am I chasing a problem that isn't a problem? Does anyone have an information or experience on the Blitz K26 setup? Overall the car drives and idles smooth. No smoke, no hiccups. Just more lag then expected with less power then expected, using more fuel then expected.

Cliffs:
-Blitz twin turbo kit @ 18 psi with lag until about 4,000 rpm, full boost at 5,000 rpm
-550cc injectors with only -15% fuel pulled at idle to get 14.7:1 ish AFR, -5% pulled up top where it leans out to 12:1 @ 100% duty cycle
-Power is strong in boost, but not close to the expected 450 whp
-Am I getting expected lag, is my ecu bad, could a bad oxygen sensor cause these symptoms, could a clogged fuel filter cause these symptoms, what else could cause unnecessary lag and low power?

Thanks in advance for any help.

 

[IndigoMKII]

http://www.supramania.com/forums/showthread.php?111624-Blitz-K26-K27-Twin-Turbo-Kit

It could be possible your stock FPR is acting up.

 

[Dylan JZ]

IIRC, that kit starts spooling at around 4 and has 18psi by 5-5.2k, so that's probably just how it is.. I'm not sure who said they wouldnt be much different than stock twins, but yeah they are.

As for the fuel issue, I'd definitely look to the FPR or possibly the pump if youve had the 550s flow tested.

 

[tErbo b00st]

Thanks for the advice.

Am I correct in assuming that I should be pulling 30% fuel at idle? I know the factory ECU will automatically correct if you are +- a certain percentage, but -30% at the AFC should result in a 14.7 idle, correct?

 

[Dylan JZ]

Yessir, Leigh. I did a quick search however just to kind of take a look at what others have said, and yeah 20-30% seems to be about right

 

[kotu100]

Leigh I thought u sold the supra, glad to see you're still sliding it.

Have you double checked the wideband a/f to insure it's accurate?
Don't forget about the timing changes the safc will make cuz it thinks its at a lower load than it actually is. Maybe this could be affecting the spool?

 

[hvyman]

Timing will effect spool. But I'd go more with that there very outdated turbos and slow to spool.

Be better off going with a single or a couple newer faster spooling turbos.

 

[tErbo b00st]

Leigh I thought u sold the supra, glad to see you're still sliding it.

Have you double checked the wideband a/f to insure it's accurate?
Don't forget about the timing changes the safc will make cuz it thinks its at a lower load than it actually is. Maybe this could be affecting the spool?

Nope, still have it. Just underwent a makeover and unveiled my new team

but anyways, yes I am very aware how the AFC effects timing. However, pulling fuel increases timing, which should help with spool. Plus, as discussed, I'm not pulling much fuel. 15%ish at idle, like 10% midrange, and 5% up top.

 

[tErbo b00st]

Also, I took my IC off and it was full of crap. Cleaned it out and spool was unchanged, but power up top feels much better.

Going to replace the FPR and see how that effects my AFRs, as well as redo some of my vacuum hoses. I'm only pulling about 13 inhg at idle, so I'm thinking I have some type of leak somewhere as I should be at 18 at least i think.

 

[IndigoMKII]

18-20 is a healthy engine with no vacuum leaks.

 

[tErbo b00st]

So I cleaned out my IC with gasoline (was dirty as shit) and removed my EBC (AVCR). boost comes on much quicker now, making 10 psi by 4k rpm and hitting 16 psi around 5k. Power also feels much stronger.

My vaccum is still low at about -13 though, so I need to figure that out. I've checked over all of the couplers and vacuum lines, and used carb cleaner everywhere to try and find a leak. Can't find anything.

 

[atmperformance]

check your fuel injector seals they like to be the hidden leak sometimes. Your EBC should work much better with the leak fixed.

 

[tErbo b00st]

check your fuel injector seals they like to be the hidden leak sometimes. Your EBC should work much better with the leak fixed.

I soaked the things in carb cleaner and idle didn't change one bit. So I've ruled that out.

I am thinking of buying one of those cheap fog machines and hooking that up to my intake tract to try and spot any leaks. Knowing everything that I've looked at, I'm thinking it may be a leak between the upper and lower manifold, or where the lower manifold attaches to the head.

 

[525gte]

10 :1 is too rich for spool in I would lean it out . 12 .0 for spooling in maybe till 3300 than start to trend richer ending at a 11.5 at 4200 and carry that out the top

what is the ex housing on these turbos and what size are the turbo wheels

is the pcv still hooked to the intake if it is its a boost leak. Leaking right into the crank case making it harder for the motor to rev

My pcv valve only held. Back about 4 pounds after it leaked

 

[tErbo b00st]

10 :1 is too rich for spool in I would lean it out . 12 .0 for spooling in maybe till 3300 than start to trend richer ending at a 11.5 at 4200 and carry that out the top

what is the ex housing on these turbos and what size are the turbo wheels

is the pcv still hooked to the intake if it is its a boost leak. Leaking right into the crank case making it harder for the motor to rev

My pcv valve only held. Back about 4 pounds after it leaked

Yea, I know that is a bit rich down low, but I'm hesitant to pull much more fuel due to the timing increase. Maybe I will try and play around with my midrange "tune" a bit more.

Not sure on the sizing tbh. There is very limited information on these turbos. All I know is they are K26, with K26 exhaust housing. with that said, I believe there are several different sizes of K26.

Tell me more about this PCV, I'm not clear. The valve cover hose on the exhaust side is dumped to the ground, while the one on the intake manifold side has the PCV valve with the short rubber hose going to the intake manifold. Is that not correct? How should I be running these? I know I "should" have a catch can. So can someone school me on the correct way to route this with and without a catch can? I will get a catch can eventually, but I have some other expenses I need to address first, and would like to fix this ASAP.

 

[IndigoMKII]

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=EC&P=4

 

[tErbo b00st]

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=EC&P=4

really dude? I have a set of aftermarket twins on top of a heavily modified engine...and you want me to route the PCV system like OEM? Not to mention that's for a 7M, so that does me literally, zero good.

Anyone, have any real help?

 

[f00g00]

http://www.toyodiy.com/parts/p_J_1991_TOYOTA_SUPRA_JZA70-BLMZZ_1201.html
The intake and exhaust covers are connected with a short rubber hose under the coil pack cover, the pcv valve goes to the intake and the exhaust cover goes to the charge pipes which you won't have and dumping to the ground would not be good. When I had a catch can I had the hose going to the charge pipe as the input to the catch can and the out going to the charge pipe. If the exhaust side is wide open the there won't be any vacuum for the crankcase to breathe when your in boost.
When not in boost the crankcase breathes through the intake side via the pcv valve. You should just as a test, plug the exhaust side which is open and see if the vacuum increases for your low vacuum problem.

 

[hvyman]

Pcv should to the intake to turbo not charge pipe. Charge pipe is ic pressured pipe.

There can still be vaccum with the exhaust side open. The intake manifold is still in vaccum and still pulling air from the valve cover. The reason it has 2 different vac sources is to cover all rpm and throttle ranges.

Since his problem is boost and a pcv valve is cheap I would not plug the exhaust side and then make a pull. Could pop the mains out and 2jz already have issues with fronts popping out.

Pcv is cheap enough to just throw at it.

Also make sure you don't have exhaust leaks as well.

 

[525gte]

Yea, I know that is a bit rich down low, but I'm hesitant to pull much more fuel due to the timing increase. Maybe I will try and play around with my midrange "tune" a bit more.

Not sure on the sizing tbh. There is very limited information on these turbos. All I know is they are K26, with K26 exhaust housing. with that said, I believe there are several different sizes of K26.

Tell me more about this PCV, I'm not clear. The valve cover hose on the exhaust side is dumped to the ground, while the one on the intake manifold side has the PCV valve with the short rubber hose going to the intake manifold. Is that not correct? How should I be running these? I know I "should" have a catch can. So can someone school me on the correct way to route this with and without a catch can? I will get a catch can eventually, but I have some other expenses I need to address first, and would like to fix this ASAP.

Here is what I did. The pic is capped. Than the other side is running to a catch can and pulling vacuum pre turbo on the Intake pipe