SR20DET pothole in higher revs

Good day everyone , seeking for advice , thoughts, what could i check more for the problem i have with sr20.

Engine is stock. Engine is controlled with ecu master classic. fuel pump walbro 450. Coilpacks are audi r8 . Sparkplugs denso ik20

Problem that i have is when we rise the boost to 1 bar ( 15 psi) we have a "pothole" @ 6k rpm .

Fuel pressure on ilde and @wot good , timing chain is spot on , base timing aswell ,checked for boost leaks there was none, coilpacks where swaped with no changes , data in ecu software looks allright. Exhaust is straight 3" pipe.

I allways use Bkr7 or bkr8 sparkplugs , but i dont think it could be spark plugs could it?

When i diconnect boost solenoid and leave it on stock boost .5 bar car runs great in all rev range with no potholes .

I will add photo of dyno graph.

Do you have a data log from the ECU of the dyno run? You should be able to figure it out by comparing your good vs. bad runs.

Could be everything from a safety for high EGT, timing reduction for knock, timing map has a reduction in timing at that boost level, heck it could even be a boost leak that doesn't show up at .5 bar. Your data log should show the ignition timing, temps and pressure values.

As David asked, are any corrections happening in the log? Is boost control duty shutting down or dropping in that area?

I've had better luck with NGK than those Denso, but they may be fine. What are they gapped to?

Coil dwell?

hello guys, thanks for replys !

if somebody have time and are willing to help , i will attach the log file , im not a tuner , so if somebody could check the log i would really appreciate it.

maybe someone will notice something out of order.

@David Ferguson iv did a boost leak test and it seems that there is no leak.

@MikeMcGinnis changed the spark plugs to bkr7es gapped them to .7mm , no difference .

Hello, I tried to review, but have a question. What RPM does the pothole start and end at, what RPM is the middle of it?

The dyno graph images are in vehicle speed so I can't tell. Usually you can set the dyno to show RPM.

You did mention the pothole happens at 6k, but your log doesn't rev that high, so if it starts there we aren't getting to see it.

Hi thanks for your time man ! The thing is i dont have other pictures of dyno graphs these are the only ones iv got , iv checked the graph my self and i saw that there is few spots where the car had 6k rpm . thing is that this is my clients car , log is from "time attack" event . so i was afraid of that , that he is not gonna get to redline . Anyway my client said that he feels that pothole at 6k rpm somewhere there. I can try to get a log tomorrow , but max what i can do is 2nd gear pull (client feels the pothole in the 2nd aswell) since car does not have technical inspection and insurance , we cant go to public highway for a 4th gear pull.

Edit , look at the video im going to attach, not an expert on this , but is this normal that i see Tps at 100% but rpms got these wierd jumps .

Here's a screen shot from your log.

Of note MAP and RPM are jumpy in the first pull shown, then you shift and floor it again and both MAP and RPM look clean. In a case like that, I'd say maybe you had wheel spin/wheel hop in the lower gear.

When an engine is misfiring, usually it gets worse in higher gears with more load, so I think what we see here is what happens at lower RPM than the pothole occurs at. This is the highest RPM in the log though.

By any chance is there a possibility that stock crack angle sensor disc is no up for task? or if it would be , you could see that in the log?

My experience with old Nissan CAS setups is they rarely work with a standalone, so I swap the triggering system out, but before you take that step, you can hold a timing light on the engine, set timing to a fixed value, and rev it into the pothole region and see if the timing mark scatters or holds on target. I think there's a 20 degree before TDC mark on those, so I'd use that for a test in neutral.