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Discussion Starter #1 (Edited)
so i have a built d16z6 pushing around 16psi with a precision 58-58 and ill explain what happens here..

so 3 days ago, it had just finished raining so it was nice and wet outside so i decided to have a little fun. i downshifted into 3rd and just as i hit boost the tires lost traction and i was able to bounce off limiter and shift into 4th while still being in boost. No issue there. This was also right after i had fixed my fuel pump wiring issue.

HOWEVER, last night i was playing around with a stage 2 mk7 gti and i shift down into 3rd to do a highway pull with this guy. THIS TIME however, when i was boosting and getting close to rev limit (7300 - 7500rpm's), it suddenly surges up to my rev limit and a big flame comes spitting out the side of the car as it fuel cuts.. my face met the windshield. id also like to add that the car seems to die until i push in the clutch again.. meaning the engine light will stay on and my gas pedal just dies and does nothing until i go to shift into 4th..

My question is, what could be causing this? does it have to do with the wiring i did for my fuel pump? the weather outside? the tune? would a dying alternator cause this? (mine's on its way out)

Ive done some research but i havent gotten a straight answer, so im wondering if you guys could help me out!
 

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Fuel pressure regulator vac line may have come loose.
What engine management you using? You pull the check engine code?
 

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Discussion Starter #3
Fuel pressure regulator vac line may have come loose.
What engine management you using? You pull the check engine code?
Im on a Hondata s300 and the check engine light only stays on for the split second that the car fuel cuts after i hit redline, i also dont have a reader :/

ill check the vac lines though
 

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Discussion Starter #6
ok so i went around the engine bay and checked all the vacuum lines around the intake manifold, none of them are leaking and all are on pretty tight. The one thing i noticed however is that i dont have a wire connecting to my MAP sensor. I even looked through the harness in my engine bay and i cant even seem to find the wire for it. Its like my harness doesnt have a plug for my MAP sensor?
 

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Meat Popsicle
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You sure it’s a fuel cut and not an ignition cut? AFAIK the Hondata ECUs can do ignition cut as a rev limiter which would make sense given the flame you saw out of the exhaust.

You definitely need to figure out the MAP situation. How would the ECU know how much fuel/spark to give it if there’s no MAP input?

Have a hard time believing there’s NO kind of MAP signal otherwise the engine probably wouldn’t run.

You should datalog during these conditions and see what it shows.
 

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Discussion Starter #9 (Edited)
You sure it’s a fuel cut and not an ignition cut? AFAIK the Hondata ECUs can do ignition cut as a rev limiter which would make sense given the flame you saw out of the exhaust.

You definitely need to figure out the MAP situation. How would the ECU know how much fuel/spark to give it if there’s no MAP input?

Have a hard time believing there’s NO kind of MAP signal otherwise the engine probably wouldn’t run.

You should datalog during these conditions and see what it shows.

Would it make sense if i said maybe the tune runs off the wideband and not a map sensor? I have no wires in my harness that are for the map sensor that’s what’s really confusing me rn

I also noticed that when I spin in 2nd gear I’m able to bounce off limiter like 2-3 times before I fuel cut.. I feel like it has something to do with the speed the car’s traveling at and if it’s spinning or not
 

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Meat Popsicle
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The ECU could be getting the AFR from the wideband, sure. It’s not at all necessary since you probably are running open loop and always referring to the spark/fuel map but some guys like to run closed loop and let the ECU refer to the narrow band signal.

In any case, that doesn’t help the ECU determine which column to refer to for spark and fuel. The ECU must know the manifold pressure to know when you’re at 16psi of boost vs -20in/hg of vacuum.

You sure you don’t have another MAP somewhere? Possibly a remote mounted MAP on the firewall with a vacuum hose connected to it or something?
 

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^^^ Possibly a map sensor mounted elsewhere; GM map sensors are usually rerouted like that. Lots of speculation could be made here though. Get a datalog and see what your engine is reading. You could also see what your map sensor settings are in ththe program!
 

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Discussion Starter #14 (Edited)
The ECU could be getting the AFR from the wideband, sure. It’s not at all necessary since you probably are running open loop and always referring to the spark/fuel map but some guys like to run closed loop and let the ECU refer to the narrow band signal.

In any case, that doesn’t help the ECU determine which column to refer to for spark and fuel. The ECU must know the manifold pressure to know when you’re at 16psi of boost vs -20in/hg of vacuum.

You sure you don’t have another MAP somewhere? Possibly a remote mounted MAP on the firewall with a vacuum hose connected to it or something?
Ok so I looked around the engine bay once more and i found something that could possibly be what we’re trying to look for..
i google a remote map sensor and it looks identical. So i guess this puts to rest the hole mystery with that.. but i still have the fuel cut

Also I’d like to mention that when I checked my injectors, 2 of them had seals that came right off when I took the fuel rail out, meaning the seals are too big for the stem of the fuel injector
 

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Ok so I looked around the engine bay once more and i found something that could possibly be what we’re trying to look for..
i google a remote map sensor and it looks identical. So i guess this puts to rest the hole mystery with that.. but i still have the fuel cut

Also I’d like to mention that when I checked my injectors, 2 of them had seals that came right off when I took the fuel rail out, meaning the seals are too big for the stem of the fuel injector
Possibly finding what you "think" may be another map sensor still doesn't help.. I see your sentiment in trying to placate those that may be getting stuck on map issue by simply locating it.. Kudos. However, there may be issues with it still..

While there are a couple things that may BE a problem, I don't suspect it to be THE problem.
You've left lots of helpful information out to help determine what may be going on. In your defense, that info hasn't been clearly asked..
Give more info about your build in regards to your tune.. Is your ECU chipped or are you running a program like Hondata or Neptune?

Reason I ask is because you may not be tuned in these areas of the map. A datalog will point you in the right direction. Are you able to datalog or not?
There are a small number of things that feel like "boost cut" that range from ACTUAL boost cut, fuel cut, ignition cut- things pointing to your tune; and an even smaller number of mechanical possibilities- boost leak, etc.. Help others help you!
 
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