Feels like fuel cut

[oneslowwdsm]

Ok so I'll start with mods:

14b with ported 16g exhaust housing
Full 3" exhaust
Intake
Walbro 190fp
o2 dump
Stock injectors
vrspeed FMIC

Symptoms:

Car runs fine at idle, regular driving and pulls hard at 15-16lbs of boost. However, once I turn it up to 17lbs at WOT around 5.5k rpms it seems like I fuel cut. It feels like it falls on its face but if I keep the pedal to the ground it picks itself back up and keeps going to 7k.

What I've tried:

I had the stock fuel pump in there then I put the 190 in only to find that it's doing the same thing.
Boost leak test (none) held 18lbs.
Swapped mafs with a known working one.
Swapped bov's from a greddy type-s to a 1g bov.
Fixed all exhaust leaks.
Replaced MDP sensor (manifold differential pressure) because I was throwing a code for it.
Swapped turbos
Replaced spark plugs with NGKBPR6ES gapped to .28
Newer BOSCH spark plug wires

It seems like I'm leaning out because the old spark plugs were white on the tips and the compressor wheel inside the exhaust housing had a whiteish color to it. But my question is why this is happening? I've had friends that ran 16g's on 20lbs with stock fuel. Any help is appreciated.

 

[nastyleak]

Sounds like you need bigger injectors, and then something to tune with. In other words, get ready to spend some money.

 

[dsm03]

Turn that boost down until you have bigger injectors and a way to tune!!!


Countless threads with people like you just because it worked for their friends doesn't mean it will work for all cars!!!

 

[Dert]

Way over running your injectors, time to go bigger and pick up link (I say link should be first mod to any DSM, after maintenance of course)


Sent from my iPhone using Tapatalk

 

[my dreamt dsm]

550 or 650 injectors, way to tune, log and call it a day!
Would of been helpful if you had a logger to show idc's. Which in this case I'm sure it's well over a certain %.

 

[oneslowwdsm]

Thanks for the info guys. I was thinking it might have something to do with the injectors. However I won't be upgrading because it's almost winter and I'm planning on storing this car and going way bigger.

Anyone else that has had the same problem and fixed it let me know. I might swap 450's just to see if it makes a difference.

 

[bryanwheat]

What is happening isn't caused from the injectors being over ran. It is caused by the maf being over ran because you are overflowing what the ecu see's as safe. The injectors being overran is going to cause it to run lean, but it will not fuel cut because of it. You need bigger injectors to be running that much boost, or atleast a logger, or wideband to see what it going on. You can't just keep turning the boost up and assume that it is ok if it is running good.

 

[oneslowwdsm]

OK so UPDATE: After a clutch swap, headgasket replacement and other maintenance things, I've come to the same issue. NOW the car is running on EVO 560cc injectors, walbro 190fp same as before however NOW I am on a tdo6 20g turbo. I thought I SHOULD be ok for 20lbs however I am not. at 16lbs it is fine. Anything over it will fuel cut. Runs great, drives great, just when in between shifts it will bog due to no tune whatsoever. (not even a wideband) Passed a boost leak test btw with no leaks.

 

[bryanwheat]

So you are on the stock ecu and 560 injectors and nothing to tune them with?

 

[oneslowwdsm]

Yes no tune whatsoever like I said. It DOES bog in between shifts however at 15-16lbs it pulls perfectly fine to 7k just once I turn it up a bit more it fuel cuts.

Edit: In between power shifts (high rpm shifts) normal shifts it's fine and with 20g really torquey.

 

[Kyle_T]

20g with 560's and still no wideband or anything to tune with?

 

[bryanwheat]

If may seem fine, but it is running rich. You will have excess fuel getting past the rings into your oil and diluting your oil. You will also get worse gas mileage and poor performance with an overly rich mixture.

 

[oneslowwdsm]

Yes I know, it's probably not the best idea. But reality is, I SHOULD be fine, if anything I should be running way too rich which obviously I'm not, hence the fuel cutting. I don't want to dump MORE money into it before I know this thing can hold high boost with no problems.

Which leads me to my next question? Is a walbro 190 sufficent for that kind of boost? I'm thinking yes but maybe not or maybe my injectors are still to small. Any input would be great.

If may seem fine, but it is running rich. You will have excess fuel getting past the rings into your oil and diluting your oil. You will also get worse gas mileage and poor performance with an overly rich mixture.

You are right. However I'm still wondering why I'm fuel cutting. It just doesn't add up.

 

[bryanwheat]

Yes I know, it's probably not the best idea. But reality is, I SHOULD be fine, if anything I should be running way too rich which obviously I'm not, hence the fuel cutting. I don't want to dump MORE money into it before I know this thing can hold high boost with no problems.

Which leads me to my next question? Is a walbro 190 sufficent for that kind of boost? I'm thinking yes but maybe not or maybe my injectors are still to small. Any input would be great.

No, the reality is that it will not be fine. Fuel cut has NOTHING to do with injectors or fuel pump. It is from flowing more air thru the maf than what the ecu is meant to read. You have a boost leak if you are fuel cutting. You can throw 2000cc injectors in there and still fuel cut with a boost leak. Do you know what fuel does when it gets in the oil? Throw the stock injectors back in, do a boost leak test and it will run fine.

 

[oneslowwdsm]

No, the reality is that it will not be fine. Fuel cut has NOTHING to do with injectors or fuel pump. It is from flowing more air thru the maf than what the ecu is meant to read. You have a boost leak if you are fuel cutting. You can throw 2000cc injectors in there and still fuel cut with a boost leak. Do you know what fuel does when it gets in the oil? Throw the stock injectors back in, do a boost leak test and it will run fine.

I DID do a boost leak test with noo leaks.

 

[bryanwheat]

I DID do a boost leak test with noo leaks.

If there are for sure no boost leaks than you aren't experiencing fuel cut. Fuel cut is only caused by one thing and that is overrunning the maf. Without any boost leaks you won't be pulling enough air thru it with a 14b at 16 psi to cause fuel cut. You could have an actual fuel delivery problem that is causing the car to lean out up top, or a spark delivery issue.