Hit another wall @ 15 psi?

[952g63t]

Car is running really good overall.

560's/Rewired Wally 255/2g maf/afpr set to 42 base/good wires and plugs

Yesterday I was out enjoying the nice weather and had a chance to stretch her legs.

I was hitting 15 psi, maybe 16 and hit some kind of wall. It wast exactly like before I did my injector and pump swap where it would just fall flat on its face, except this time I was in higher gear.

I'm thinking its my injectors, but I was hoping some experienced guys could chime in and confirm this.

thanks,

 

[GRAVEDIGGER]

Have you done a proper boost leak test? If not it's time to do so.

 

[1sick_gst]

What's your AFR's reading when this occurs?

 

[Dsmkauai]

Sounds like fuel cut to me. 560's arnt that much bigger than 450's bro! What are you using to dial the new injectors in? What's the Idc? If you must Bump the fuel pressure up alittle if you want push the 560's alittle more. You really need a way to see idc% so your not going over like 80% or 100% if you really want to push them. (Not recommend)

 

[97 eclenger]

Do a boost leak test. A bov with weak spring or waste gate going bad will open prematurly

 

[952g63t]

I am running a 1g bov. That would make sense seeing how they are only good up to about 13 psi?

A/F was fine, and I did do a boost leak test recently when I did my upgrades albeit I only tested up to about 10 psi.

I will mark this as resolved and report back after I swap to a better bov. I am going in on the group buy with NGR.

Thanks for the help.

 

[Turboturd]

I am running a 1g bov. That would make sense seeing how they are only good up to about 13 psi?

A/F was fine, and I did do a boost leak test recently when I did my upgrades albeit I only tested up to about 10 psi.

I will mark this as resolved and report back after I swap to a better bov. I am going in on the group buy with NGR.

Thanks for the help.

No, the 1g bov will do 17-20, just varies between BOV's. Now if it is crushed it could be a different sotry, I've seen crushed ones do all kinds of weird things. Regardless, it wouldn't cause the "wall" that you are describing.

I would say factory fuel cut, unless you have removed it with tuning software

 

[codym]

I am running a 1g bov. That would make sense seeing how they are only good up to about 13 psi?

A/F was fine, and I did do a boost leak test recently when I did my upgrades albeit I only tested up to about 10 psi.

I will mark this as resolved and report back after I swap to a better bov. I am going in on the group buy with NGR.

Thanks for the help.

Why would you boost leak the system at a lower pressure than what you'll be running ? If your running 15lbs, I'd ensure the system is holding pressure at 20lbs.

 

[Rikolas]

Why would you boost leak the system at a lower pressure than what you'll be running ? If your running 15lbs, I'd ensure the system is holding pressure at 20lbs.

I was about to ask the same question. If you don't pressurize the system to the same as how much boost you are running, if not more, you can't be 100% on if it's holding the pressure or not. Do anot her blt with the correct amount of pressure and see what the outcome is.

 

[johneclipse]

FYI, for whoever said the 560s are too small. I ran 550s at 25 psi on a 14b at 75% idc. 560s should be plenty on 15 psi. Even more so if he's running a factory t-25 on the 2g

To the OP, you have nothing to tune with? I know the general information is "2g maf with 550/560 injectors works". However this was FAR from the truth on my 1g. With the combo I required tuning, otherwise I hit fuel cut just like your doing.

 

[donniekak]

If you just installed larger injectors, with no way to tune them, the car is going to run like crap.

 

[952g63t]

Let me correct myself; I leak tested to 15lbs.

Honestly, it runs great with the way its currently setup. Of course, excluding the issue discussed.

My thinking is that I could be experiencing MAF overrun. Why would it hit fuel cut if I was not maxing out my duty cycles? I have more than enough fuel at the adequate pressure.

 

[ScuzziOne]

IIRC, "fuel cut" is based on airflow readings which has nothing to do with injector duty cycle. If the ECU sees "too much" airflow as measured by the MAF, then it assumes there's a boost leak and cuts fuel injection. So the problem is reaching this "fuel cut" airflow reading due to performance modifications and increased boost. You can have a perfectly running engine, but when the MAF hits the prescribed "fuel cut" output, then the injectors get shut off.

 

[c2ypt1c]

Yes, fuel cut is based soley on the airflow, completely independent of the fuel system.

My thinking is that I could be experiencing MAF overrun.

The 2g maf limit, not fuel cut but the actual frequency limit, happens around 50lb/min...is your car making 500hp?

This sounds like a boost leak, but could be an ignition issue. When was the last time you changed your plug wires? EDIT: just read they are good...

What's the gap on your plugs?

 

[donniekak]

How are you compensating for the injectors?

 

[donniekak]

What afr is the wideband reading at wot?

 

[Dsmkauai]

No one said that 560's are to small. I said they arnt much bigger than 450's so don't expect much more. I have 550's on my gvr4 and run 17psi no problem. When I had them in my gst on a 16g at 20psi it was around 80-85% duty cycle so I went up to 850's for breathing room so idc% isn't so high. O.p. what is base fuel pressure and how did you check this? Base fuel pressure is 43.5 not 42! How are you tuning which just about everyone has asked? There's no way your over running the maf! http://www.dsmtuners.com/forums/frequently-answered-dsm-questions/186971-what-fuel-cut.html if your hitting fuel cut you simply need to add more fuel to balance out the maf airflow reading. If you just threw injectors in and didn't dial them in your going to have the same issues you did with the 450's and probably hit fuel cut. Way back when I first got a 16g I hit the brick wall easy trying to run higher boost. Ecmlink, 550's and a walbro 190 rewired fixed that up easy!

 

[My1GLaser]

You'll know fuel cut when it happens...it's like someone chained the back of your car to a tree and the chain just ran out!

Like they mentioned, it happens when the stock ECU sees too much airflow for the stock fuel system to handle. You could have two 255 pumps and 2150 inj but the ECU doesn't know if it doesn't have a chip, so it cuts the fuel supply so you don't run lean and blow something up. Get a chip or ECMLink.

Running an AFC or MAFT delays the fuel cut since it lowers the airflow reading, but it will still happen if you run enough boost.

 

[donniekak]

Is nobody here realizing that he just installed 560cc injectors, with no tuning solution! Fuel cut is going to happen at the same flow range as if no larger injectors were installed. The Ecu is seeing a stock un modded airflow signal, and just treating the 560's as if they were 450's.

 

[Archer Fabrications]

Is nobody here realizing that he just installed 560cc injectors, with no tuning solution! Fuel cut is going to happen at the same flow range as if no larger injectors were installed. The Ecu is seeing a stock un modded airflow signal, and just treating the 560's as if they were 450's.

There were 5 or 6 people asking about his tuning solition but op dodged it each time.... And read the post above yours.

 

[Dsmkauai]

That's what I've been saying since the beginning!!

 

[952g63t]

Sorry, didn't mean to dodge any questions.

No tuning solution.

I thought I would be fine as long as I didn't go past a certain injector size. My idle and cruise a/f is stoich, the times I have been able to pay attention to my a/f at WOT it has been at or very close to 11:1

I will perform another BLT for you guys, and report back with a solid AF reading.

Thanks,

 

[Archer Fabrications]

You need at LEAST an SAFC

 

[codym]

Could also get a chip for the injectors.

 

[952g63t]

Fixed.

It was either a bad plug(s) or wire(s). Replaced both after I reset my base fp to 43.5.

Did a few pulls, and inched up the boost to 18-ish psi. My A/F are at 11 - 10:1 at WOT.

No cut.

I have some video Ill upload here in a minute.

Thanks for the help.

Edit: Video did not turn out. I dont have a proper mount so its sh*t basicaly.

Here's the base pressure setting: https://www.youtube.com/watch?v=sv59UJdCDkI

Can't see wideband, sorry. https://www.youtube.com/watch?v=nxXZW6qa8rQ