1jz cutting out at wot

[300zxpwns]

i'm having a problem with my 1jz and my friend has a mk3 2jz that is also having the same problem and we can't seem to figure it out. Anytime i am wide open doing a pull, once i hit full boost the car starts to sputter and cut out. It only does it under 100% throttle.
i just changed the plugs and gapped them right around .30, checked for vacuum leaks, map sensor is good.
mods are:
3inch exhaust
hks intake
stock twins
safc and wideband

i have noticed when it cuts out that the afr's are staying about the same and not changing much. any help would be much appreciated. thanks

 

[supra1008]

Are you sure you're using the right plug? You might need a colder stage plug. I was having that problem when I turned up the boost. It would drive fine but under boost it would hesitate. I changed the plugs to a colder stage and it pulled hard all the way to redline.

 

[suprahero]

How much boost are you running? As I increased my boost, I had to decrease my gap. I'm now running 22psi and my plug gap is .020
Try to lessen your gap by about two thousands and try it again. You should be good to go if there isn't anything wrong with your tune or your car.

 

[supra1008]

Yea that too^ lol

 

[300zxpwns]

ok cool, i'll give that a try tomorrow. it is running 14-15psi right now. Whenever i go out to do a pull it seems like the first pull or two it doesn't stutter but then the more pulls i do it gradually gets worse. I'll try gapping and we can go from there. thanks guy

 

[Bigzavs]

if u keep havin trouble man, just give me a ring, i can probably come by or meet up with ya to see if we cant figure it out

 

[10secdream]

Could be worn out coils. I would check for cracks.

 

[honestabe]

What plugs are you running? You should be using NGK 4644's (formerly BKR7E) gapped at .028. Have you heat shrinked your coil stems? If not, you should. I did this with mine and it cured the exact same stumbling. For extra protection I used 2 layers of 1" heat shrink on the coils to ensure they were well insulated.

 

[300zxpwns]

ok cool. i'll gap the plugs and do the heatshrink tomorrow and report back. thanks

 

[suprahero]

Do you have a wideband installed? I'd hate to know it's leaning out for some reason and you keep running it. Hopefully it's just the plug gap or the wrong plug. I too use the NGK 4644's.

 

[slideways2004]

sounds like you are hitting boost/fuel cut. i believe it cuts out at around 14-15 psi.

 

[airhead04]

sounds like you are hitting boost/fuel cut. i believe it cuts out at around 14-15 psi.

Have you ever hit fuel cut? Definately isnt a putter as he said. More like hitting a wall.

 

[300zxpwns]

Do you have a wideband installed? I'd hate to know it's leaning out for some reason and you keep running it. Hopefully it's just the plug gap or the wrong plug. I too use the NGK 4644's.

wideband installed yes. wot its around 13.2-13.5 with 10%fuel added with an safc. When i try to add20-30% fuel to get it in a safe zone it starts to cut out. I gapped the plugs to .025 and it seems to help some, but still has issues and can't get passed 20% fuel adding.

yea its def not boost cut. lol i have hit that before and it almost kicked my car sideways lol. would trying to add 25% more fuel max out my stock 1jz injectors with an safc 1?

 

[slideways2004]

Have you ever hit fuel cut? Definately isnt a putter as he said. More like hitting a wall.

yeah, after re-reading it, its not boost cut

 

[supra91gsxr06]

cant it be, if u have a old fuel pump, the stock one.

 

[300zxpwns]

i was wondering about fuel pump. when i got my swap it came with a fuel pump so i threw it in, but i have no idea what kind it is. The shop i got it from said it didnt look like a walbro. The motor came with an intake and downpipe so i'm wondering if its some aftermarket pump.

 

[Bigzavs]

might have been the stock jza70 pump

 

[suprahero]

Nobody else is worried about the 13.2 - 13.5 @ wot? I know I'm a pussy, but if mine is anything above 11.6 @ wot, I get all queezy inside.

 

[Bigzavs]

Nobody else is worried about the 13.2 - 13.5 @ wot? I know I'm a pussy, but if mine is anything above 11.6 @ wot, I get all queezy inside.

ya that is kinda troublesome, at most i dont wanna see higher than 12.0:1 on my car.


give me a call this week and ill help check it out

 

[300zxpwns]

is the stock jza70 pump any good or is a walbro better?

and yes i'm worried about the 13 afr. I dont want it any higher than 11.8 max, but i cant add enough fuel to get it down there without it cutting out.