you might want to gap your plugs down a bit. I had the same problem on my Supra TT and thought it was fuel cut but all I needed to do was regap the plugs. Start out at 26 and see if that works. if it does but you r idle is a little off just gap up to 27 or 28 and try that again. This worked wonders for me, it just seems that at high rpms with the boost the spark can't jump the bigger gap and feels like you are being cut.

scott

 

i figure 43-44 psi is good to go since that is the standard pressure fuel injectors are rated. raising it up that high could see better tunability with the safc. i currently have mine at 42, but had it at 44 for more than 6 or 7 months.

 

At first I thought my problem was ign related (I had similar problems with my car before I blew it up) until I saw my O2 readings. Holy hell. from 10.9:1 to 17.6:1 in huge spikes. Horrible.

EDIT: My point being you should run it with a WB monitoring or on a dyno and see if you're definitely missing fuel or if it's ignition related.

 

i have the wb.. havent gotten a chance to run much with it because i havent had the time.... but the thing is... I can creep to 5 psi.... if i Try to mash it... or hit anything past 5 psi my af gauge goes banana's..... goes from rich to lean about 100 times per second... and my engine starts to studder... if I let off the gas and accelerate again... no problem.. untill i mash down or reach over 5 psi.. and the funny thing is.... It doesnt happen in first gear... 90% of the time i can go all out in first gear.

 

edit:: my vac pressure at idle is -21(hg) which is hella vaccuum and when i had a vaccuum leak it was reading -10hg then i fixed leak and went down to -21hg

 

-21 x 0.49 = 10.29

The conversion for in Hg to psi is 0.4911541 psi per 1 in Hg just FYI (since this came up in the vac/boost gauge thread).

I shoulda remembered you had the WBO2 considering how long we talked about it. What reading does it give when you try to reach peak boost?

 

as zlancer said before, there's something weird with the fpr. in 1st gear, and then each gear after, the AF ratio through the band is slightly leaner. i get .98v+ in 1st as opposed to .90v+in 3rd. though narrowband is inaccurate, it would ideally equate to 12.1 and 12.8. you might be barely making the correct AF in 1st but missing the rest. raise pressure to 44 psi and check the hose from the manfold to fpr for any damage. you're relying heavily on the fpr to give you juice on boost.

 

but I still dont think that this will fix my problem i think i can pump my fpr up to 100 psi and still nothing will work.. but anything is worth a shot i guess

 

Andrew... i really dont remember off the top of my head but i can def send you some readings if you want... Ill even send you the software.. if you dont mind taking a look and telling me what you think.

 

are you sure it's not 0.4911541153483248641354. . . how'd they come up with that?

side note :: raising fuel pressure lowers throughput of the fuel pump. i don't quite understand by what effect quite yet, but i thought i'd throw that in there.
http://www.roadraceengineering.com/f...pflowrates.htm

 

i'm pretty sure the problem is the FPR...you gotta be like a god to tune that thing correctly.

 

Have you tried swapping out FPR's for another rising rate or something?

 

my air fuel ratio is fine in first gear also, but any thing after that it is bad anywhere from mid 13s to high 15s, and just like jvlancer if i creep up on it slowly it will stay fine, its like some component cant keep up if you floor it.

 

I'm sorry I was linked to this thread and only read the first few post and skimmed over the rest. If going positive on the afc is giving you fuel cut it obviously does work because it is affecting the mas signal. Check out how a afc works and then you will understand. By adding fuel on the afc you are adding mas signal which gives it more fuel. It can only do that to the point where the ecu sees way too much airflow signal and then goes into safety hence fuel cut. Easiest way is just to get bigger injectors intead of trying to run the afc at +30 etc. Get 30% bigger injectors and work from there if you need that much fuel.

I don't see any reason why afc would not work on this car. It is pure BS to say that it doesn't without saying exactly why it doesn't.

Now this is also very very simple explantion and it is much more in depth than I made it seem so if you really want to read more just go look at any dsm board and search for this topic which has been covered many times.

 

Also, I don't see why you would need to go so high on the afc. Definately go over your fuel system and make sure all is good. Also the dec air function will not do anything on a karman setup.