Does this make sense?

[ChezoGTR]

ive got a fujitsubo exhaust with cat delete in my r33 gtr and when i really step on it, it feels like im loosing fuel pressure. so i was talking to a couple guys last night and they said that because i have the fujitubo with cat delete im boosting higher then stock adn my car is completely stock even ecu. they said im probably hitting my boot limiter and its cuting fuel on me. make sense?

[archaeic_bloke]

no... whats does a "loss of fuel pressure" feel like to you exactly? can you describe that process...

[ChezoGTR]

feels like im getting no fuel and its missing. the car just jerks and backfires. but it only does it under very high load

[derbeck]

Sounds more like regular fuel to me. Or plugged fuel filter or mafs

[MarusGTR]

no... whats does a "loss of fuel pressure" feel like to you exactly? can you describe that process...

Feels like reverse Vtec, YO.

In all seriousness Chezo, constant, uniform loss of pressure at WOT would be vacuum leak based. If it's jerky it could be from fuel to ignition. Check your FPR to make sure that the vacuum line from the rail is connected to the block. IIRC people here say that the line makes the pressure go up, but I recall also the manual saying that without the line it makes the pressure max out through the powerband.

Check your plugs and coils; they could also be losing spark at high boost. Also, clean your MAFs. You ARE running a little more boost than stock because of the decat, so a problem in that area is more likely. What's your max boost btw? Do you still have the restrictor?

Frankly, if it's fuel based wouldn't you be more prone to feel it right after you shift at WOT and make the pump surge again?

Edit: What did they mean by boost limiter? How would it cut fuel? They meant that the ECU would be running with it's maps maxed?

[ChezoGTR]

Feels like reverse Vtec, YO.

What's your max boost btw? Do you still have the restrictor?

Frankly, if it's fuel based wouldn't you be more prone to feel it right after you shift at WOT and make the pump surge again?

Edit: What did they mean by boost limiter? How would it cut fuel? They meant that the ECU would be running with it's maps maxed?

everything in the car is bone stock man. minus the exhaust and cat delete and i dont really feel it after shifts i get the odd backfire after a shift but it sounds more like a fart then a backfire and some guy said there is a limiter programed in to the ecu to stop you from over boosting on stock oem ecu. and i have no clue what my max boost is i still have the -7 0 +7 gauge. also what do you mean by restrictor?

[ChezoGTR]

Sounds more like regular fuel to me. Or plugged fuel filter or mafs

94 octane cahnges the filter two days ago and cleaned the mafs

[ChezoGTR]

changed**

[greddytrustGTR]

So it's bogging? Does it run pig rich when u tromp on it?

[hozer]

If it feels like a rev limitter hitting your boost then you are hitting a boost limitter. I would kinda describe the feeling like putting your hand on and off your carpet vaccum nozzle.. Chunking air feeling...

I have a boost limit on my car and if ambient temps hit below ~8 I start to over boost and I would describe hitting the limiter fairly similar to how you did.

[DJ]

coilpacks loosing spark

[Nismo_line]

try replacing your plugs too. could solve your missfiring issue

[ChezoGTR]

yeah i keep hearing people saying replace your coil packs. any good brands and sites you know of i can get some off of?
or if any of you live in winnipeg you know who would be able to get some? option, gas, ect?

[Dragon Humper]

Get to the basics;

check/change your plugs, check the vacuum line to your FPR (it must see boost pressure to compensate for the pressure in the intake manifold pushing back at the fuel as it comes out of the injectors), the factory boost guage should not be maxed out if the restrictor is still in place and you are making only .7 bar of boost, have someone follow you and make it stumble so that they can tell if it is rich when it is doing it (if it is rich, your spark is being snuffed out).

Gap a new set of plugs at .8mm and get back to us. Don't waste your money on Plats or Irrid., plain copper is better for fending off pre-ignition. I personally use AutoLite AR3923.



Jon.

[ChezoGTR]

thanks Jon ill do all that and get back to you