Car not boosting smoothly!

teedoff00

14 psi boost
Dec 5, 2007
297
0
16
Selah, WA
Ok, So I have recently finished getting some stuff fixed and sorted out and up until now I have been running about 7 pounds of boost. I almost never boost much past 4500 rpms and usually never go all the way to WOT and I guess this is why the problem has never been apparent. So I turned my AEM Tru-boost up to about 12 pounds to start to tune my way to 14 or so where my power goals are. When the boost comes on it starts to pull and the gauge stays pretty steady at about 12 but the car bogs or doesn't boost smoothly throughout the rpm range. I turned to controller off which put me back to like 7.8 and it boosted fine all the way through. I figured it must be the spring (crack pressure) setting on my ebc was too low so I changed it up to what I figured would be just wastegate regulated of 7.8 psi. That didn't change anything. When the controller was set about 8 psi boost it still bogged at crack pressure of 3 and didn't do it as bad when it was at 7.8 crack pressure but still did somewhat.
So... I would like input on what could be causing my boost to be coming on like this?
I have checked:
1. Boost leaks, been a problem in the past, but recently swapped out all my clamps for t-bolts and checked my couplers/pipes. So as far as I know there are no maft based leaks.
2. Fuel pressure is set at 26 with vac connected. Running lexus/550's/walbro/12 v mod/Aeromotive AFPR (kit eliminating j tube and FPD)
3. Checked for codes and it is clear.
4. Checked throttle cable and it looks to be tight.
5. Checked timing with T1 and E1 jumped, and everything was good at 10 BDC.
I do experience some lurching/bogging when at certain throttle levels like 1/4 way and below 3 rpms, and I don't know if that is related. This is getting really annoying, even more so since I wan't to get my car up to about 14 pounds or so, so I can go get it on a dyno for a fine tune and to see what she can do.
The rest of my mods are: Rebuilt 7m, MHG, ARP Studs, Act Clutch, AEM UEGO, CT-26 57trim.
Any help, ideas, questions for further research would be great, meanwhile I will keep searching in hopes of finding a similar case.
Thanks in Advance!!
 

teedoff00

14 psi boost
Dec 5, 2007
297
0
16
Selah, WA
So just doing some more searching, and maybe it could be the spark plugs/gap? Could I be getting the spark blown out? I am running Heat range 7 NGK iradiums (before I knew that coppers were probably better:3d_frown:). Should I try NGK coppers gapped to about .028 (tsrm specifies .031 but hear less is better on more boost) if so heat range 6 or 7? Plan to run 15 pounds max. Probably 350 rwhp max... if that...
Thanks
 

supraguy@aol

Well-Known Member
Dec 30, 2005
4,241
44
48
Atlanta
Your fuel pressure is only 26psi?
I have mine set to about 35. I thought stock was in the low 30's.
Someone smarter than me please chime in on this. I use a gap of .28 on NGK coppers.
No problems here.
 

teedoff00

14 psi boost
Dec 5, 2007
297
0
16
Selah, WA
TSRM states 23-30 with vacuum connected. My afr's are inline with the amount of boost I am trying to run. I am at 11:1 to 12:1 under WOT. So I am pretty sure the fuel isn't the issue. Any more ideas?
THANKS GUYS!!
 

teedoff00

14 psi boost
Dec 5, 2007
297
0
16
Selah, WA
OK I have an update!
I swapped in some new NGK Coppers (6097), and it seems to be running/boosting much better now! They are gaped at .028, now my only question is... What kind of boost/power can I run on these? I have heard of some using them all the way up into the big numbers? I think they are one heat range above stock, is this correct? Will they handle 15 pounds and 350 rwhp or so? But so far it is boosting much better with no cut out at 12.8 pounds.
Thanks a lot for responding IJ and confirming the spark plug idea since it has seemed to solve my problem. I will update again when I have new information.
Thanks again!