S14 SR20DET Bogging Issue Under Boost WOT

I have tried all kinds of things and have had no luck.  Please read this to make your assessments, as I have gone through all the preliminary.  I drove the car for about 8 months with no problems after my rebuild and it ran really awesome after my break in period (500mi) then I was driving one day and all of a sudden the car acted like it was out of gas or the fuel pump was going out.  I filled it up and then put a new Walbro 255 in but the problem didnt go away.  Let me go over the mods I have as I recently built the motor a year ago:
1997 Nissan 240sx S14 SR20DET
Engine:
1993-96 S14 SR20DET
12,000 miles on motor
CP Pistons 86.5 mm
Eagle Rods
Extra capacity oil pan
Cometec headgasket
ARP Head studs
BC Valves & Springs & Retainers
BC 264 Cam intake and exhaust
Tomei Rocker arm stoppers
Megan Equal length mandrel bend exhaust manifold
Garrett T2871R .64 ar Turbo
Apexi Super suction kit
Circuit sports pulley kit
Hks Bov
Tomei 750cc Injectors
Fuel Pressure Regulator
Enthalpy Reflash ECU
Nismo motor mounts
ACT lightweight flywheel
Spec Stage 3 Clutch
B&M Short Throw
Driveshaft works Aluminum Driveshaft
LSD V200 J30 Differential
Apexi NOIR Catback (Super Quiet)
Aftermarket FPR w gauge
Blitz Icolor
Blitz Turbo Timer
Z32 MAF W Super Suction kit Apexi

Now let me go over the stuff I have replaced recently to try and fix the issue:
TPS
CTS
VTC
MAF
CAS
Fuel Pump
Fuel Filter
Spark Plugs
Igniter
Resistor
Knock sensor

Now let me go over the symptoms I and then the checks I have made:
-Symptoms only start after the motor has warmed up for about 20 min but will run great when the motor is coldish (before 20 min)
-Wide open throttle it will bog out at 3-4k rpm mostly in 1st and 2nd gear then if you let off the gas it will even out and boost all the way to red line
-It runs very rich and will backfire when shifting from 1 to 2 to 3rd sometimes
-Just pulling the throttle under no load there is a hesitation, very weak throttle response.
-Only boosting 10-12 psi for finding the issue purposes but I like to boost 14 psi normally
-Feels like there is no power from idle untill the turbo kicks in and then as long as I am about half throttle it will run great without bogging.

Check List
-I have replaced all the aforementioned stuff above with new or known good parts
-Using boost leak tester I put pressure through the whole system and plug any leaks I find (Doesnt Fix)
-Check plug gap set to .025
-Check FPR 36-42psi even adjusted it to 50psi (gets worse) down to to 32psi (little better but still not fixed)
-Coils are withing spec approx 1 ohm
-Maf values are within spec 1.2v at idle to 4.8v full throttle (double checked wiring and ground)
-CTS Values are within spec
-Grounds: Every single ground I can find and track down I have loosened and retightened
-Checked all relays (Some strange things there) more later
-Timing set to 15+- 2 deg
-No ecu codes
-Sent ecu to Enthalpy to have them check it they say it runs great on their car
-Set the TPS voltage to .45v
-Checked all the input and output voltages for all of the aforementioned parts.
-Checked O2 it was very clean like new.
-Double Checked CTS
-Boost leak test again: Found that the HKS SSQV leaks sometimes. (Its about five years old and has been on the hot pipe side so the rubber is hardened and the springs dont set the valves properly every time.) This could be the culprit waiting on a new BOV.

-Grounds: FSM says to check with the key off and they all are close to 0 ohms to ground but with the key on it jumps to 100 ohm not sure if that matters or not and I have checked everywhere for a short to ground and have found none.  Checked all ecu grounds as well as every sensors ground.    
-Relays: Checked the ECCS relay and it is at 11v even with the relay is out but with the relay in it is 12v not sure if it was always like this or not and I havent found any burnt wires or anyplace it could be shorted.  This is the two White Black wires at pin 49/59 on the ecu and only go to the MAF CAS and turn on the Ignition coil relay.  Possibly someone spliced it in the harness before I got it because it was missing that relay when I first got the swap.  It runs and while running supplies battery voltage with the eccs relay out.
-Wiring: All in all I have been very careful to check every wire when I did the rebuild.  I took all the factory tape off and re wrapped it myself while checking for any cut burnt or frayed wires and have found none.
-Shorts: I dont know if I can rule it out because I check some power wires to ground and the and they read 75 OHMs resistance Like the eccs wire that goes to MAF CAS.  But there is also 75 OHMs on the Ignition coil wire that goes to  all the coils.  And I am also reading 75 OHMs on the injector power wire and that comes straight from the ignition switch... Could it all be a problem with the ignition switch or the turbo timer wiring in there, I will check.  Nope not it it is 75 OHMs after the ignition switch with it unplugged. I rip the whole harness out to find this but I dont even know if it is the problem.

Anyway I wanted to be very thorough so please only respond with kindness and professional courtesy because I am already at a short fuse.     

Thanks
Charles
S14 Kouki

Check your o2 sensor.

gOtPUrPL3 wrote:

Check your o2 sensor.

I am under the impression that the o2 plays a very small role in doing anything it is basically just for emissions.  The WE ecu is from a 93-96 S14 SR20DET and is OBD 1.  The O2 was replaced when I did the rebuild a year ago.  Also I did a test mode two and it flashed the mil light at least five times every ten seconds while at 2k rpm.  (within spec).  I will check again anyway thank you.

This sounds very close to the problems I have been having for a few months now as well. Except I have more low end than top end power. Everything you have checked and gone over sounds spot on as to what could have possibly been the problem. Maybe it's leaning out under full throttle?

RAD MIKE Circa 3006 wrote:

This sounds very close to the problems I have been having for a few months now as well. Except I have more low end than top end power. Everything you have checked and gone over sounds spot on as to what could have possibly been the problem. Maybe it's leaning out under full throttle?

I dont think it is because if I crank the FPR to higher pressure then it gets worse.  It really sounds like it is getting flooded because it will shoot some serious flames when i shift right after bogging. I have tried turning the fpr down and it got slightly better but it still doesnt fix the issue and I dont want to lean it out to much.

Zubasky wrote:

gOtPUrPL3 wrote:

Check your o2 sensor.

I am under the impression that the o2 plays a very small role in doing anything it is basically just for emissions.  

The o2 sensor controls the a/f ratio. You're thinking of OBD2 cars that have a second o2 after the cat. The second o2 is strictly for emissions purposes.

02 sensor does not do much on older engines. i never even had one in there when I had an SR. My corolla didnt have one either.

Probably because you were stuck in open loop due to not having an o2 sensor. You should have been running a little rich. The o2 sensor reading is what the ecu uses to determine a/f ratio when it goes into closed loop. Of course, it it doesn't get any reading at all, it will just stay in open loop which has a predetermined fuel map. You probably wouldn't notice too much of a difference on an NA car, but on a turbo car having the a/f off would be much more noticeable.

Seriously though, what does an o2 sensor cost? $10? Just replace the damn thing and call it maintenance.

Maikeru wrote:

Probably because you were stuck in open loop due to not having an o2 sensor.  You should have been running a little rich.  The o2 sensor reading is what the ecu uses to determine a/f ratio when it goes into closed loop.  Of course, it it doesn't get any reading at all, it will just stay in open loop which has a predetermined fuel map.  You probably wouldn't notice too much of a difference on an NA car, but on a turbo car having the a/f off would be much more noticeable.  

Seriously though, what does an o2 sensor cost?  $10?  Just replace the damn thing and call it maintenance.

Ah, They are $75 and if you didnt notice I have thrown lots of money at this thing already. The O2 does not control A/F that much and besides it is less then a year old with maybe 15k miles on it. I will check it anyway thanks.

Check those injectors too

gOtPUrPL3 wrote:

Check those injectors too

Ok I just checked the O2 and it looks brand new there is little to no carbon on it. And the Voltages are in spec.
I did listen to the injectors and they all sound the same. None of the plugs where really fouled like a bad injector might do. They all are less then a year old and got new orings put on when I did the rebuild.
I do plan on putting new orings on in the near future. But a leaking injector doesnt seem to be the cause because it seems like all the cylinders bog out under WOT.

Check the coolant temp sensor.

and make sure you coil harness isnt wedged anywhere or messed up at all.

gOtPUrPL3 wrote:

and make sure you coil harness isnt wedged anywhere or messed up at all.

Double checked CTS and also
Looked very closely at the coil harness and no rubbing, kinks, looseness, or fraying that I can find. Please read the updated Shorts info above and tell me what you think. Thanks

Hi there I am new to this forum... not even from the Chicago area. I just wanted to say thank you for putting so much info on this forum about your ride. It sounds very frustrating all that you're going through. I reply because my brother is having the same exact symptoms as you are having minus any backfiring..... yet. I have been trying to help him research this bogging issue on his car with no avail. Only one other forum I read has a similar issue, but it's a bit older thread and there was no resolution submitted.

So down to brass tax, we have performed almost every check you have tried on your vehicle except for the wiring voltage/continuity checks, fuel pressure, and ECU inspections. Though they are on the list next for this weekend coming up. Oh also his SR20DET Blacktop has bone stock internals, with an HKS Intake, Greddy BOV, and a front mount intercooler.

Just wanted to 1.) See if you found the culprit. 2.) attempted to perform a fuel injector flush(my bro's SR was running fine for 2 weeks, installed recently. I'm starting to wonder if a fuel injector is cracked and only noticeable under load due to fuel pressure being higher).

Anyway I will update after we attempt the fuel injector flush and we can see those injectors in action.

Update: so I did as any mechanic with any sense would do... Start all over checking very mechanical and electrical possibilities with a fine toothed comb so to speak. I finally found the issue. For some reason cylinder one was beginning to arc through coil pack contacting the valve cover. A normal issue, but it just happened twice with two different oil packs. Maybe stroke of luck that they were both bad. We're trying out a new coil pack, maybe even upgrading to Spkitfire ignition.

Will update in the coming weeks to see if issue persists. But for anyone that is have the same issue mentioned at the beginning of this thread, double and triple check your coil packs for arcing. These symptoms on my brother in-laws car were almost unnoticeable until he was attempting to reach 6lbs of boost and up. Anything lower and the car barely sputtered or bogged. A plus it didn't help that he had cleaned all coil packs because they "looked dirty". Anyhow I'm glad I he asked me for help instead if wasting money at a shop. Back to basics guys. Good luck.