Datalog numbers look great but popping in high RPM's

[DJ23GSX]

Alright i have searched and tried just about everything I've found so far and I still can't get rid of this popping at high rpms. So far i've done a fuel filter bpr7 plugs gapped at .028 magnecor wires coil pack tried differnt wires thought maybe the magnecor's were arcing and an intake leak test but i can't get rid of this problem. I run 93 octane gas. My datalog numbers are great but when the boost creeps up to around 17-18psi my o2 volts drop to .02 but i have 0 knock about 20* timing and i am at 81% d/c i did notice that when the o2's drop my timing seems to advance instead of retard and my d/c stays around 75-80%. I am pretty convinced its not an ignition problem but a fuel problem but i am just can't understand why my #'s look pretty good then all of a sudden i get the pop? I've read that many people run 16-17psi on a 16g with a bigger fuel pump and stock injectors. Why can't I? The most i've seen my injectors read is 91% d/c and even when my o2's are at .78 my timing is 18* and my knock is usually between 0-5. Is there anything else i can try before buying 550's and a SAFC??

These are my mods:
Fully balanced motor with 4 layer metal head gasket and ARP head studs and all brand new internals and a brand new ported head with 3 angle valve job. Ported 16g,Ported 2g exhaust man and o2 housing, 3" turbo-back exhaust, 3" intake pipe with K&N, ACT2600 SS line, MKIV i/c, 2.5" upper and lower i/c pipes, Magnecor's, bpr7's, Fluidyne radiator, Walbro 255lph pump

 

[NOSLO2PT0]

This "pop" you are experiencing, is it a bunch of short stuttering pops, or a really big BANG, hestitation, then acceleartion, then BANG, again? If that's it, you are hitting fuel cut. If it's the former, the short stuttering variety, you are having timing pulled. I"m going with the fuel cut, since you say your O2's drop to .02.

 

[DJ23GSX]

its different each time some times its a big pop and some times its just a little studder. My timing actually goes up when the o2v's drop. Seems to happen at lower rpm in colder weather so i am leaning towards fuel cut. The only thing i am wondering is are there different levels of fuel cut? pretty much everything i've read about fuel cut is this violent pop like you just hit a wall and mine isn't nearly that bad.

Thanks
D.J.

 

[NOSLO2PT0]

Still sounds like fuel cut to me, especially if it happens moreso during cold weather. Either get a TMO chip, or install larger injectors to push the fuel cut back.

 

[CYCLONE]

I am currently having the same problem but only in 4th and 5th
gear. Starts at about 5000rpm, I know its not fuel cut for sure
because I ran into that many times before. I even put some 100
octane in to see if it would change but no luck. Let me know if
you figure anything out with that.

 

[dthquazi1]

you know when you get fuel cut. And by the way with all your stuff i would have had the 550's already. Especially if your running 17-18 psi.

 

[DJ23GSX]

Originally posted by dthquazi1
you know when you get fuel cut. And by the way with all your stuff i would have had the 550's already. Especially if your running 17-18 psi.

Every mod i have was purchased to replace blown or broken parts. The only reason i am running 16-17psi is because the boost creeps. I don't have a boost controller.

 

[Gula]

I'm experiencing the same sort of problem. I will let you know if I find a solution.

 

[DJ23GSX]

Well i did a little experimenting today just to see if this was fuel cut. I unhacked my maf and put in the silencer in my muffler and back in the intake to try and cut the boost creep down a bit. It only creeps to 12psi now and guess what....no pop or studder of any sort. It was definatly fuel cut which is kind of a relief because i've been trying to figure out this problem for a while. I just couldn't figure out why somedays it would pop and some days it wouldn't that made me think it might be an ignition problem but after changing nearly all my ignition components it was still there. When i used to hit fuel cut in my talon it was a much more violent pop and bang.

 

[Gula]

That's good news. I hope my 2g MAF solves my problem.

 

[NOSLO2PT0]

Installation of a 2G MAS by itself usually INCREASES the chance of fuel cut, or brings it on earlier, as you must run even RICHER to compensate. You need to do things to DECREASE the airflow signal, I.e. run leaner on the AFC. That includes raising the base fuel pressure, buying a bigger fuel pump or buying larger injectors. Those things push fuel cut back. Or get an Eprom ECU and have a chip installed that takes care of fuel cut altogether.