yea, sounds like FC.

I beleive FC happens when the MAS exceeds a certain flow rate. I've also read it's when the fuel injectors hit 100% duty cycle but I'm not sure about that one.

It's all about saving the engine from self destruction. FC saves you from melting holes in pistions, etc... You are basically flowing more air into the engine than it can handle fuel wise, so it will lean out dangerously.

Makes sense about the MAS value because most FC fixes are related to modifying its signal to the ECU.

Anyways, before you think about stopping it from happening, you need to start making changes to fuel management to make sure you stay in a safe fuel/air ratio. For now, try not to hit that too often because you are sure to shorten the life of the motor if you regularly hit FC.

Do a little more research on the VFAQ sites etc...

 

Yes, you're hitting fuel cut. Have you followed the 'lower' honeycomb removal VFAQ? Follow the VFAQ and remove the lower honeycomb from your MAS and your fuel cut issues will go away.

-Joe

 

my honeycomb is out, screw backed out, and i hit fuel cut badly(atleast i think it is fuel cut) with a Big16G ported and clipped around 18-20 psi. it goes away when i turn the boost down to around 15 psi, so im assuming it is fuel cut. i am going to get rid of the straight piece in the lower(un-metered) part of the mas and see if that helps. is this normal for i big16g or should i be ok with my mas hacked the way it is??

 

Yes, fuel cut is normal when you are not fooling the ecu into seeing less airflow. The 16G is quite capable of going over the fuel cut inducing flow limit that the ecu has in place. The easiest way to delay fuel cut is to use larger injectors and an AFC to allow the ecu to see a lower airflow count.

 

i have rc550's and an afc, i wouldn't run 20psi on stock fuel guy.

 

Arent AFC's really expensive? I know that i am dumping alot of fuel though because as i said she stays full rich on my gauge.

Do you think 94 is too low a grade for 20psi? Cause we have that at the station next to my house!

 

94 is awesome for about 18psi...my friend Ran 94 just fine til 18psi...here in Florida we have 92-93 Octane Rating....if we wanna add about 2 more psi of boost we generally add some B-12 Chemtool to raise it up about 1-2 octane points.

 

AFCs are generally $250 when bought used and they are quite abundant.

I run 22 psi daily on 93 octane pump gas. There are guys pushing the limits much further than I on pump gas. In other words....94 octane is fine.

 

A Dejon style MAS bypass will basically prevent fuel cut to 23+ psi on a Big 16G. (I have not gone past 24psi, yet)But, it will lean you out, requiring more fuel from increased pressure or larger injectors. Remember that all cars are different and just because I can run 18 on 450's without timing pull with 93, or 20+ on 100 octane, does not mean everyone can. The only way to be safe is to log regularly, especially as variables change, such as new mods, even temp changes. My car runs leaner/stronger as temp decreases, as do most. But that leanout has a cost- need for more octane, or water or alky injection, or maybe propane if you want to be on the cutting edge like Erik. In any case you MUST have pocketlogger or dsmlink to tune safely. Good luck.

Joe

 

DsmLink?

 

Oh and i checked Dejon's site and didnt see a MAS bypass thing. Where is it?
Thanks.

 

okay, what about your plugs and plug wires? you're running an aftermarket fuel pump, 550cc injectors, and only a 16g and you think you're getting fuel cut?!?!?!? nah, i doubt it. i'd almost bet it's either your plugs or wires. when's the last time you changed them, what kinda plugs? ngk's? dual prong or single? platinum or regular? and what's the gap? what kind of wires?

i'd maybe think fuel cut if it were stock fuel components but you have them upgraded (well, if the mods on your sig. are correct anyway). i'd check out the ignition 1st before spending bigger bucks on other things. if it's not up to par, the air from the turbo blows out the spark......not gonna ignite the fuel, and you get the same feeling as fuel cut. speaking from experience. and a friend of mine just had the same problem. he thought it was fuel cut as well but i told him to change his plugs and wires and it solved the problem. just my 2 cents. don't spend it all in one place.
scott

I know that i am dumping alot of fuel though because as i said she stays full rich on my gauge.

just one more reason to check it out.

 

TMO stage 3 chip! takes all thefuel cut blah blah blah stuff.. bad if you dont know hat your doing

cheaper note, get a 2g maf and an AFC. 2g maf ..big diffeence.

 

Oh and i checked Dejon's site and didnt see a MAS bypass thing. Where is it?
Thanks.

It is an intake pipe that replaces the stock rubber accordian intake, and has a 1.25" fitting welded on to attach a K&N breather filter.

Joe

 

V8s are slo,
I have monsterous plug wires... they were on it when i got it (should add those to the list) but i dont know about plugs... Suggestions?

Joreitman,
But i need an AFC or VPC to use that Dejon pipe right? Cause it gets rid of the Mass Airflow Sensor.

And lastly... how much can i get a 2g sensor for... is it just plug in and go? Or do i have to wire it in?

Thanks.

 

Does not get rid of MAS, just replaces the accordian rubber tube/pipe that connects MAS to turbo compressor inlet. It may require you to get bigger injectors though, unless you have higher fuel pressure from an aftermarket fpr and/or larger fuel pump. You may need AFC to fine tune, although I do without and O2s are fine. I log regularly to ensure operation within safe tolerances.

I think 2G MAS uses a different connector, so there is some splicing/wiring, fairly easy I understand. I will probably never go to 2G MAS because the modified 1G MAS does so well.

Joe

 

2G MAS=$100-$150
K&N intake for 2G MAS=$50

Then you need to spend a little bit of time cutting and splicing the 1G MAS harness to the 2G MAS harness. Nothing hard though.

 

if you ARE getting fuel cut (although i'm not thinking so) you don't wanna be flowing more air. that just leans things out even more. as for your fuel system, do you have an aftermarket fpr? cause you may have a bigger pump and overrunning your stock fpr. also, as for plugs, i'd only stick with ngk's. you've had the stuff on there since you've had the car huh? well, how long have you had it? just because the wires are big, doesn't mean they'll last forever.

as for the plugs, you wanna make sure they're gapped at .028. also wanna get the "SINGLE" prongs. they do make duals and you don't want them. regulars, not platinum. that would be the 1st thing i'd check out. heck, if you have any buddies that live nearby or something, i'd see if they'd let you switch out plugs and wires, just for troubleshooting measures. let us know about the fpr as well though. laters!
scott

 

"if you ARE getting fuel cut (although i'm not thinking so)"

I used to fuel cut on my old 14B by 19 psi before hacking MAS

"you don't wanna be flowing more air."

More bypassed air is fine IF fuel system supports it.

"that just leans things out even more. "

All MAS mods are geared to bypassing the upper honeycomb through which MAS metered airflow passes. Fuel cut is triggered by what the ECU sees as excessive airflow, so the more airflow is bypassed away from the upper hc area, the more fuel cut is put off. Leaning out is not all bad as long as O2's are monitored and knock is not excessive.

"as for your fuel system, do you have an aftermarket fpr? cause you may have a bigger pump and overrunning your stock fpr. "

This will cause richness and sometimes rich detonation but I don't think it contributes to fuel cut.

"also, as for plugs, i'd only stick with ngk's. "

Agreed

"as for the plugs, you wanna make sure they're gapped at .028. also wanna get the "SINGLE" prongs. they do make duals and you don't want them. regulars, not platinum. "

Agreed

BTW, someone mentioned a relationship between fuel cut and IPW/ Duty cycle. I run 20+IPW (over 100% duty cycle) at WOT often and Never get fuel cut, due to MAS hacks. I think airflow is the only factor at play with fuel cut.

Joe

 

yeah sorry, i was thinking, if you are running LEAN then you don't wanna do the mas mod. not fuel cut. but as for the fpr, he said his gauge was showing he was running rich. that could be a possible cause of that if he can't drop the fuel pressure.

This will cause richness and sometimes rich detonation but I don't think it contributes to fuel cut.

this is true, but doubting you're having fuel cut anyway.
scott

 

OK you all have me confused a bit... My intake elbow to the MAS is metal, the one from Dejon... Has the neck for the BOV return but its plugged off... obviously. What MAS hacks are you all refering to? I havent touched the mas, it just has the noise filter removed.
Basically i am wondering is whats the easiest and cheapest way to kill fuel cut? I know its fuel cut because when it happens my o2 gauge snaps to FULL LEAN, meaning fuel is being cut.
How to get rid of it is the problem... I can kinda do it by not hammering it... but thats not as fun. I also know im getting enough fuel because it runs 60PSI and runs a bar or so under full rich on my Auto Meter gauge.

 

my gauge did that too. here's what happened to me. when i was modding my car, i had had new plugs from the dealer. but they were dual prongs. i got to the point with my mods that what would happen is that i would flow enough air to blow out the spark. during normal driving, no problem. but if i floored it, when the boost would get high, it would buck and kick hard. i thought for the life of me it was fuel cut. never would've dreamed it was the plugs cause they were brand new. i got the plugs that was listed in the manual....not knowing at the time that the dealer had single prongs too. someone just happened to mention plugs and told me that the dual prongs suck!!! so i went ahead and changed them out for the single prong. problem cleared up immediately. sure the gauge is gonna jump to the lean side. it's like everything is shutting down all at once. i'm giving you my 2 cents.....i could be wrong but that's just my experience. also, do you have an aftermarket fpr? never did get any feedback on that one.
scott

 

I will try the plug thing.. i mean it makes sence it only happens with my turbo SNAPS too full boost OR if im at HIGH RPM! Shit.. could be... hope it is!
No aftermarket FPR.
What do you suggest? Does it still adjust with vac and boost like stock one?

 

"Has the neck for the BOV return but its plugged off"

If you unplug it and install a K&N there you will flow a lot of unmetered air- MAS bypass. This will lean you out so a logger is needed to monitor things.

Other MAS mods are backing out the screw in the MAS and removing lower honeycomb. See vfaq.

Joe

 

OH i c... hmmm but wont that be HORRIBLY lean though? And idle like dog shit?