sputtering under boost

[sleepersupra]

ok heres the deal, i did a full rebuild and everything thats included in that...i did walbro, 550's, lexus afm, and the car is now hesitating under boost. it used to do it a little different when my timing was off...but since i fixed that it is more or less sputtering instead of missing.

i replace the fuel filter today hoping that was the problem...checked my codes and it came up 32 which iirc is the hac. i plugged that in and still same code still same problem. any suggestions would be awesome.

also it has new plugs and wires.

 

[robbo185]

boost leak? check everything again

 

[drbowser3]

Your sig says this......"Apex'i SAFC II not tuned*" This most likely is your problem. Mine was doing similar things, so I pulled some fuel out, and that cleared it up.

 

[MKIIINA]

whats your gap for the plugs at? too big and it can cause studdering at upper rpms and boost

 

[sleepersupra]

well the safc is uninstalled (untuned) and the plugs are ngk iridium 1-step colder and i thought you don't gap them.

and as far as the boost leak are we talking about just intercooler pipes?

 

[SupraDreamPDR]

i vote boost leak... check all you IC hoses for cracks, make sure all the clamps are tight and not stripped out. also check all your smaller vaccum hoses and your BOV.

 

[hottscennessey]

this is very doubtful but notable.. on my car i was messing with the DP, and unhooked the O2 sensor, I forgot to reconnect it and drove around.. my car sputtered and was running lean under WOT which is very weird considering the O2 sensor wasnt used much in WOT. But anyways check it out, there could be a short in the circut.

 

[cartman]

I bet your running too rich. I have the exact same fuel setup and when i was untuned on the safc it would run extremely rich and start sputtering especially at higher rpms (5k+). Since I tuned it it pulls strong all the way to redline.

 

[antman]

assuming that everthing in your sig is installed other than the apexi, and considering that you did the lexus upgrade with the 550's. I am going with week spark. double check all the related connections. do you have any broken coilpack harness clips?

 

[Boostedstr8six]

If you can't find any apparent boost leaks in the usual areas you might think about checking your injector o-rings and grommets to make sure they are seated and/or to see if they are cracked.

Also, did you drill out or eliminate the J-tube restrictor when you installed the walbro?

 

[sleepersupra]

ok to answer some of the questions to narrow it down....

1. i don't know about the o2 it's plugged in so i don't know

2. it could be rich, but until it's tuned then i'm stuck with it?

3. all the connectors on the coils are great, i checked the ohms volts and all the specs for the coils, and the ignitor

4. no the j-tube is still there cause i need the fiting to make my fpr hook up to the fuel rail.

 

[supra_driven]

i say u double check ur gap on the spark plugs. When i bought some new platinum plugs for my car they were at .040" and the car was missing up top. I regaped them and it went away. BTW i'm running NKG Iridiums.

 

[antman]

i say u double check ur gap on the spark plugs. .

i agree, its definatly worth looking at. .

 

[sleepersupra]

i say u double check ur gap on the spark plugs. When i bought some new platinum plugs for my car they were at .040" and the car was missing up top. I regaped them and it went away. BTW i'm running NKG Iridiums.

ok i'll check but what should they be gaped at?

 

[mysupra87]

If you can't find any apparent boost leaks in the usual areas you might think about checking your injector o-rings and grommets to make sure they are seated and/or to see if they are cracked.

Also, did you drill out or eliminate the J-tube restrictor when you installed the walbro?

how do you remove the j-tube?like what all is involved.

 

[sleepersupra]

how do you remove the j-tube?like what all is involved.

i took the j-tube braket off and grinded the plate that was connected to it off and then remounted the plate.

 

[hottscennessey]

^ yup, just to elaborate because i was confused about it way back when... but its a hard fuel line from the fuel pressure regulaor which is mounted to the block, this line only allows about a pinhole of fuel to flow through it, wich may cause the fuel pressure to become very high.. running you off the charts rich. This is usually just after a walbro installation. To fix it, just drill out the restriction, or bypass it alltogether. When bypassing it you can grind the tube off the "plate" which mounts to the block. this keeps it looking clean.

 

[suprahero]

I'm not positive, but I think that I read on here somewhere to gap them to .028.......That's what mine are gapped to right now, or at least they were when I put them in there..................good luck.

 

[suprahero]

I just did a search and found out that stock is .040, but if you have upped the boost, you can gap them to .028. You just have to try and see if that is right for your car. Hope this helps.

 

[sleepersupra]

I just did a search and found out that stock is .040, but if you have upped the boost, you can gap them to .028. You just have to try and see if that is right for your car. Hope this helps.

thanks for the info.... it never fails that you guys always help thanks