RB20 cutting out under boost. NEED HELP!!! Tried everything

[MATTs14]

Ok so my buddy just replaced the headgasket on his rb20 after unseating due to faulty installation of the thermostat (stupid, i know, thats what i thought too). Well he got a killer deal on a smaller frame turbonetics and an hks log manifold and decided to go ahead and swap these on since he was gonna be doing work on it anyways.

We swapped in the turbo with a used hks log mani and the typical hks wastegate that you see with it. We also swapped in the gtr injectors along with the resistor that is required accompanied with a carl h tune and a z32 maf to suit. At first it wouldnt start and after repeated attempts we realized that he had wired the maf wrong . He got it switched around and it ran, but really rought. He replaced the o2 sensor and the plugs along with a full fluid change.

ALong to the problem. When the car builds boost above say 5 to 6 psi, it will start sputtering and cutting out. It feels like a fuel cut because the car will lurch forward and sound like a very fast paced repeated miss. You can shift out of whatever gear you are in and it will run smooth until you start building a substantial amount of boost. Also you can go around quarter throttle and it will run to redline, this may be because it keeps it out of boost, but still not sure if this is the problem.

My diagnosis at first was that it could possibly be the igniter, we swapped mine in and it didnt affect it at all. We adjusted the fuel pressure up and down and it also didnt affect it all so we set it at the usual 36 and moved on to others. I believe that the fuel pump is fried since at initial start the regulator was maxed out and allowed it to pump way over 100psi, im not sure of the exact amount since the gauge only goes to 100 and it pegged out. It runs rich on initial start up and smooths out as it warms up. The wideband is reading well with afr's in the 12's under boost and around 16 when cruising.

Anywho, let me know what you guys think. The kid is so frustrated with the car that he's ready to sell it, so help me help him so we can keep another rb enthusiast in the world. Thanks again guys

[Carl H]

are you guys 100% sure that there isnt a boost leak somewhere hidden?if the boost leak is large enough and can cause the maf to max then it will cut out.

[MATTs14]

Im not sure we can check but it builds boost great all day. Any other suggestions??

[WhatsADSM]

Im not sure we can check but it builds boost great all day. Any other suggestions??

Just because it builds boost does NOT mean it is leak free.

Also just because you look at the pipes and maybe tug on the them a bit and nothing seems out of the ordinary, that also does NOT mean it is leak free.

Build a boost leak checker and check it.

[MATTs14]

I'll definitely check it out and go from there. Thanks guys and keep the suggestions coming. All help is appreciated. THanks

[tight240]

Check MAF wiring, did you guys use shileded wire? Solder and heat shrink wrap (butt connectors are a big no no )?Check for codes in the ecu, knock sensors can cause this to happen.Make sure you guys are using copper spark plugs.Switch out the MAF if the MAF wiring is ok.Make sure your coils are not arcing.Check resistance across each coil pack, they should be no more or less then 7 or 8 ohms i believe.Boost leak( like stated above) check for them as well.

I have a feeling its a MAF issue tho, any takers on that? i have a open pot here...... takeing bets.