Boost leak, or poor tuning??

[B-lackGSX99]

My car runs perfectly fine under mid-low throttle, but as soon as I pin it (WOT) or give it high throttle, the car will build boost up to around 10psi, bog for a few seconds (stutter), build to full boost (17psi) and power normally. If I go WOT from a stop, this doesn't happen. It really only happens if i'm rolling at a normal (traffic speed), and floor it, for example: rolling in 3rd gear at 50kph, at ~2700rpms and flooring it, or even if I downshift into second and floor it.

It revs up, spools midway, stops spooling/revving (still at 100% throttle), goes "bupapapapaapapap" for 1-2 seconds, then continues revving/spooling normally right to red line.

I replaced my spark plugs with brand new correctly gapped (to .028) NGK BPR7ES's last week, so I have eliminated that as my issue. I have been reading a lot of threads about boost leak symptoms, and it sounds to me like if it were boost leak, the car wouldn't be able to recover from the bogging after a few seconds (please correct me if i'm wrong). From the reading, I want to go check at what rpms this is happening at, as it may be an indication of poor engine tuning on my SAFC, resulting in an overly rich condition that is causing the car to bog for those few seconds.

If anyone can offer me any insight on the situation, that would be great...I will be running through the troubleshooting over the next while and will update accordingly, but would appreciate encouragement on what paths to prioritise in diagnosing the issue.

 

[UsMarine20M]

I would check for a boot leak and if thats not the problem go from there.

 

[B-lackGSX99]

Thanks, I was mainly hoping to verify that a boost leak can be pushed/spooled through, haven't noticed that happening to anyone in the numerous threads that i'd searched.

 

[forcefed 95]

I would do a boost leak test as it never hurts to do 1. But i dont think its a boost leak becasue you said from a rollin stop that you can do wot pulls at 17psi. Now how at 17psi do you not have a leak but at 10 psi you do. Im thinking its got a to with your a/f settings. If you got a logger i would log a couple runs and go from there.

 

[spoonman]

I would say it is definitely not a boost leak but with the fuel management.Check a/f settings.

 

[B-lackGSX99]

Yeah, that's along the lines of what I was thinking. I've been down to the track a couple times over the past few weeks, and it runs the quarter mile with no bogging whatsoever. I don't have a logger, but what I was thinking of doing is running the car, seeing if it bogs at a consistent RPM...if this is the case, then i'll increase the A/F ratio at this RPM, and see if this leaning process dissociates the car from the bogging.

The car was on the dyno a little over a month ago, tuned fully...i'm thinking it was tuned overly aggresively in terms of fuel richness (tuned to ~10.8 A/F at WOT at his suggestion). The tuner mentioned to me recently that he'd like me to bring it in for a $100 re-tune, as the car may have drifted a little bit from the last tune (apparently common on OBD-II's)...is this really a possibility, or is he just covering his messy tracks? Or is it possible that he's tuned it correctly for 1/4 track circumstances, which just don't translate over well to street style driving (i.e. WOT pulls from a roll)??

BTW, i'm only running a mid 13 second 1/4 mile, trapping at just under 100mph. At the dyno last month, I recorded only 245awph...i'll check for boost leaks eventually to try to get that buttoned up, I was really hoping (conservatively!) to post 300awhp

 

[dsm-onster]

I've had a huge split in my intercooler hose go for months because my car drove fine out of boost and from 4500 rpms on. . . After that boost leak test, I've done one at least at every oil change since.

 

[B-lackGSX99]

Okay, so i'm driving home from work yesterday, and (from writing the posts yesterday, and reading the responses) instead of looking at my boost gauge to see where the stuttering happens, I decided to keep an eye on my rpms. I noticed that the stuttering was actually consistently happening at ~3300rpms! So, I pulled into my parkade, pulled out the SAFC-ii, and noticed that my hi-throttle settings had been tampered with, everything was normal, but the 3400rpms setting was set to +10. The neighbouring RPM settings were at ~-35, so it was a pretty clear spike in the graph. Anyways, I set it accordingly to keep the curve nice, and it seems to be running like a champ now!

I'm going to print off a label stating "DO NOT TOUCH" and stick it on there. I could totally see someone in my passenger seat bored while waiting for me to come back from running into a store quickly, and playing with the controller that I normally leave on the Monitor screen.

Thanks for the help though, it was greatly appreciated.

 

[forcefed 95]

Galde to see you got the problem fixed and that it was an easy one at that.

 

[dsm-onster]

Okay, so i'm driving home from work yesterday, and (from writing the posts yesterday, and reading the responses) instead of looking at my boost gauge to see where the stuttering happens, I decided to keep an eye on my rpms. I noticed that the stuttering was actually consistently happening at ~3300rpms! So, I pulled into my parkade, pulled out the SAFC-ii, and noticed that my hi-throttle settings had been tampered with, everything was normal, but the 3400rpms setting was set to +10. The neighbouring RPM settings were at ~-35, so it was a pretty clear spike in the graph. Anyways, I set it accordingly to keep the curve nice, and it seems to be running like a champ now!

I'm going to print off a label stating "DO NOT TOUCH" and stick it on there. I could totally see someone in my passenger seat bored while waiting for me to come back from running into a store quickly, and playing with the controller that I normally leave on the Monitor screen.

Thanks for the help though, it was greatly appreciated.

I'd track them down have someone by the balls if they mucked w/ my maft settings. You're talking it better than me. . .

 

[spyderturbo007]

I'm going to print off a label stating "DO NOT TOUCH" and stick it on there.

Actually, you can lock the SAFC-II so no adjustments can be made without inputing the correct security code.